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66-96 Ford Broncos - Early & Full Size
tjg8675

Cooling System Issues

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Posted (edited)

Hi All,

I have been having cooling system issues for a while now (years I've been dealing with this), mostly a very erratic temp gauge, to the point I'm scared to go up steep grades and big hills for very long or risk overheating. I mostly stick to flat roads and an occasional hill here and there. The last time I took it up a big hill the temp went way past the "NORMAL" range on the gauge and almost into the red before I reached the top of the hill and I was able to coast down to cool it off. I have known for a while that my old radiator was clogged with corrosion (wouldn't even drain out of the petcock valve, too plugged up), so last weekend I bit the bullet and installed a new all aluminum "Cold Case" radiator, unfortunately this did NOT solve my problem. I still have the erratic temp gauge (temp goes up to between the M and A on gauge when accelerating and goes down to between the N and O when coasting). I remember when the temp gauge would stay steady between the N and O and never move, even up huge steep hills and would like to see that performance again.

This is what I know...

-I am running a 192 degree motorcraft thermostat which tested good before putting in new radiator.

-New radiator (flushed system a week before installing new radiator, filled with water and Prestone System Flush and ran for a week until draining and installing new radiator)

-New radiator cap

-Filled with 50/50 premix

-Fairly certain all air is bled out of system (I usually hear gurgling from the heater core during startup when air is in system)

-Water pump is a couple years old, this was one of my early attempts at fixing problem, also didn't work

-Replaced Fan Clutch , also a couple years ago but didn't fix problem

-I also replaced the Temp sender to gauge and ECT when water pump was replaced (How tight should the Temp Sender be? I remember screwing it down until it stopped which seemed odd to me at the time, seemed to deep, and have wondered if this might be part of the issue, maybe sender is touching the metal of the block and either blocking the way or giving bad reading because it is not supposed to touch metal???)

Any help appreciated

thanks in advance

 

1995  5.8L Bronco XLT

189,000mi

CA emissions compliant

Edited by tjg8675

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There are a couple of thoughts I"m having here.

When I went to solve my over heating issue I found mud in the A/C condensing coil (the part infront of the rad). I also had to flush the mud from between the fins for the rad. Once I had all the external parts clean I took the radiator and ran the garden hose through it. Lots of orange muck came out. I spent 45min going back and forth between the inlet, outlet, and cap to fully flush the tubes. Whats nice is you skipped most that work be going with a new radiator. However it would be interesting to revisit the condensing coil. 

I also flushed the block and heater core. I got some orange junk from out of the block so based on that experience I would recommend it if you havn't done so already. The only other thing I can think of is the pump and thermostat. But you said that the thermostat has been tested so the only think left is to inspect the water pumps ability to move the coolant through the system.

 

However all that might be going too far. The first basic step might be to install a real temp gauge and see if a over heating problem is present or if your gauge goes wack when the engine is under load.

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Yo T,

Following in 1996 Bronco Workshop Manual (partial) via http://www.diesel-dave.com/vehic/manual/stj/stjleft.htm

Starting from the basics first;

B1 CHECK COOLANT LEVEL;  NOTE: If engine is hot, allow engine to cool down before proceeding.  Remove radiator cap and check coolant level at radiator coolant recovery reservoir.

Is coolant level OK?
Yes No
GO to B2. REFILL as outlined. REFER to Cooling System, Draining, Filling and Bleedingin the Cleaning and Inspection portion of this section. GO to Pinpoint Test A.

B2 CHECK COOLANT CONDITION

Check coolant for contaminants such as rust or corrosion. Also, check for color discoloration.

Is coolant condition OK?
Yes No
GO to B3. FLUSH system. REFER to Cooling System Flush Procedure in the Cleaning and Inspection portion of this section. RETEST system.

 AS Skitter advised:

●B3 CHECK FOR AIRFLOW OBSTRUCTION

  • Visually inspect A/C condenser core and radiator for obstructions, such as leaves or bugs.
Is there any obstruction?
Yes No
REMOVE obstruction and CLEAN A/C condenser core and radiator in the Cleaning and Inspection portion of this section. RETEST system. GO to B4.

●B4 CHECK WATER THERMOSTAT OPERATION

  • Allow engine to run for 10 minutes.
  • Feel the inlet and outlet heater water hose and the underside of the upper radiator hose.
Are the upper radiator hose and heater water hoses cold?
Yes No
REPLACE water thermostat. REFER to Thermostat, Water in the Removal and Installation portion of this section. RETEST system. LEAVE engine RUNNING. GO to B5.

● B5 CHECK COOLING FAN●

Check for proper cooling fan clutch operation.

●Perform Fan Clutch Test. Refer to Component Tests in this section.

Did cooling fan clutch operate OK?
Yes No
CHECK the following:
  • Rust or scale in radiator
  • Water pump shaft and impeller
  • Collapsed lower hose
REPLACE fan clutch. REFER to Cooling Fan Blade and Fan Clutch in the Removal and Installation portion of this section. RETEST system.

¤¤¤¤

Fan Clutch Test

 

Spin the fan. A light resistance should be felt. If there is no resistance or very high resistance, the minimum and maximum fan speeds must be checked as follows:

Refer to Fan Clutch Specifications at the end of this section.

Minimum Fan Clutch Requirement Test — Cold

  1. ani_caut.gif WARNING: TO AVOID THE POSSIBILITY OF PERSONAL INJURY OR DAMAGE TO THE VEHICLE, DO NOT OPERATE THE ENGINE UNTIL THE FAN HAS BEEN FIRST EXAMINED FOR POSSIBLE CRACKS AND SEPARATION.

    Using a suitable marker, mark the water pump pulley (8509), one of the fan blade retaining bolts and the crankshaft pulley (6312).

  1. Connect a tachometer to the engine.

  1. Install a throttle adjusting tool.

  1. Connect a Sun Strobe Light or equivalent. This can be an SLT-1 or SLT-2 Strobotach or an STA-1 Strobe Trigger adapter for the Sun Distributor Test Stand. A Digital Photoelectric Tachometer 055-00108 or equivalent may also be used for this test.

  1. Start the engine and run it at approximately 1500 rpm until engine temperature has normalized.

  1. Adjust the engine to the testing speed in the Specificationsat the end of this section.

  1. Operate the strobe light at water pump test speed and aim it at the water pump pulley. Adjust the engine speed until the light flashes and the water pump pulley marks are synchronized.

  1. Aim the timing light at the fan retaining bolts. Adjust the strobe light until it is synchronized with the marked fan retaining bolt (fan appears to stand still).

  1. The fan speed must not be greater than the specified fan test speed at water pump test speed.

  1. Turn the engine OFF.

  1. If the fan speed was greater than the specified fan test speed, check for proper parts usage.

    If the correct parts are used, replace the fan clutch (8A616).

    If the part(s) are not the correct ones, replace the part(s) and perform the test again.

  1. If the engaged fan clutch requirement test is going to be performed, do not remove the tachometer, strobe light or throttle adjusting tool.

  1. If a Maximum Speed Fan Clutch Requirement test is not going to be performed, remove the tachometer, strobe light and throttle adjusting tool.

Maximum Speed Fan Clutch Requirement Test

  1. ani_caut.gif WARNING: TO AVOID THE POSSIBILITY OF PERSONAL INJURY OR DAMAGE TO THE VEHICLE, DO NOT OPERATE THE ENGINE WITH THE HOOD OPEN UNTIL THE FAN HAS BEEN FIRST EXAMINED FOR POSSIBLE CRACKS AND SEPARATION.

    If the disengaged fan clutch requirement test was not performed, follow Steps 1 through 5 under Minimum Speed Fan Clutch Requirement test.

  1. Block off areas on each side of the radiator in the engine compartment and the front of the radiator grille (8200), this will raise the temperature of the air striking the fan clutch and should cause the fan blade to operate at maximum speed.

  1. Place the air conditioning selector, if so equipped, in the maximum position and the blower switch in the high position.

  1. Adjust the strobe light to water pump test speed.

  1. Start the engine and adjust it until the water pump pulley is synchronized with the strobe light. This will be near the engine testing speed given in Specifications.

  1. Synchronize the timing light with the fan to fan clutch retaining bolt.

  1. The fan speed must meet or exceed the specified minimum fan blade test speed at water pump test speed.

  1. If the fan speed was less than the specified fan test speed, replace the fan clutch.

Specifications @ http://www.diesel-dave.com/vehic/manual/stj/stj33040.htm#spec330

¤¤¤

Burping the coolant system; this is by Ford;
WARNING: DO NOT STAND IN LINE WITH OR NEAR ENGINE COOLING FAN BLADE (8600) WHEN ENGINE (6007) IS RUNNING.
WARNING: NEVER REMOVE THE RADIATOR CAP (8100) UNDER ANY CONDITIONS WHILE THE ENGINE IS OPERATING. FAILURE TO FOLLOW THESE INSTRUCTIONS COULD RESULT IN DAMAGE TO THE COOLING SYSTEM OR ENGINE OR PERSONAL INJURY. TO AVOID HAVING SCALDING HOT COOLANT OR STEAM BLOW OUT OF THE RADIATOR (8005), USE EXTREME CARE WHEN REMOVING THE RADIATOR CAP FROM A HOT RADIATOR. WAIT UNTIL THE ENGINE HAS COOLED, THEN WRAP A THICK CLOTH AROUND THE RADIATOR CAP AND TURN IT SLOWLY TO THE FIRST STOP. STEP BACK WHILE THE PRESSURE IS RELEASED FROM THE COOLING SYSTEM. WHEN YOU ARE SURE ALL THE PRESSURE HAS BEEN RELEASED, PRESS DOWN ON THE RADIATOR CAP (STILL WITH A CLOTH), TURN AND REMOVE IT.
1. Fill the radiator with a 50/50 mixture of the specified engine coolant concentrate and water. Allow several minutes for trapped air to escape (bubble out) and for engine coolant to flow through the radiator.
2. Replace the radiator cap to its fully installed position, then back off to the first stop. This will prevent high pressure from building up in the cooling system during this part of the fill procedure.
3. Start and idle the engine until the thermostat opens and the radiator upper hose becomes warm.
4. Shut off the engine and allow the engine to cool. Cover the radiator cap with a thick cloth and cautiously remove it. Step back while the pressure releases. 
5. Finally, check the radiator and add more engine coolant if needed, following the procedures noted above. Reinstall the radiator cap securely, when finished.
6. If more engine coolant is necessary, fill the overflow reservoir to the appropriate level marked on the bottle..."
if ok;
●If the heater water hoses are too hot to hold, the thermostat is OK
Install the water thermostat in the intake manifold opening with the copper pellet or element toward the engine (6007) and the thermostat flange positioned in the recess. If the water thermostat is improperly installed, it will cause a retarded flow of coolant.
attachment.php?attachmentid=20013&stc=1&

¤¤¤
Img_4781.jpg
"... the spring side of the thermostat goes into the intake manifold. take the upper hose off and make sure its the right direction.." by kingfish

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Hi Miesk5 and Skitter,

Thanks for the info

So far

B1 - Yes - Radiator filled to spout and overflow filled to cold fill line (maintains this level after 26 mi round trip to work and back)

B2 - Yes - Coolant brand new  when new radiator installed Saturday 3/23

B3 - No - New radiator installed 3/23, condenser cleaned summer 2018 no dirt, mud or obstructions

B4 - No - Upper radiator hose and heater hose very warm to touch after warmup

B5 - Cannot run test there is no Fan Clutch Spec for 5.8l 351w (please advise if fan clutch spec is available somewhere else for 5.8l) I think I installed a severe duty fan clutch when I changed it a couple years back (is this OK?) I was doing a bit of towing at the time and thought this would be better, not much towing these days though

also...

-thermostat installed correctly

-A/C condenser clean (I replaced entire system last summer, except condenser which I thoroughly cleaned, no mud or debris present)

I will look into a temporary temp gauge to check if dash temp gauge working correctly

Thanks for the info so far

 

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Yo,

I checked other year Bronco and F 150 fan clutch specs and they too don't list the 5.8 either.  Local dealer service manager may be able to help.  However our local Ford dealers managers just want to rack up bogus "needed repairs".

Did find one Bronco Technical Service Bulletin (TSB).  A TSB is used to correct errors in manufacturing, changes to components, etc.TSBs frequently (but not always) address a recurring problem and include illustrated instructions for repair, a list of the parts needed, the warranty status and the labor charge.

Here it is, but no 5.9 Specs

TSB 92-15-14 Fan Clutch Diagnosis
Publication Date: JULY 15, 1992
LIGHT TRUCK: 1987-92 BRONCO, ECONOLINE, F-150-350 SERIES
1988-92 F SUPER DUTY
ISSUE: A comprehensive diagnostic procedure has been developed for determining if the engine cooling fan clutch is functioning properly. A fan clutch that is not functioning properly may cause engine cooling concerns and/or vibration.
ACTION: Use the following diagnostic procedure to determine if the fan clutch is functioning properly. A fan clutch that is not functioning properly should be replaced.
CAUTION: DO NOT ATTEMPT TO MODIFY THE BI-METALLIC COIL ON THE FACE OF THE FAN CLUTCH.
DIAGNOSTIC PROCEDURE
NOTE: PROCEED ONLY AFTER COMPLETING THE ENGINE COOLING DIAGNOSIS PROCEDURE IN SECTION 03-03 AND THE ACCESSORY DRIVE BELT TENSION PROCEDURE IN SECTION 03-05 OF THE APPROPRIATE SERVICE MANUAL.
1. Turn off the air conditioner, heater-A/C fan and radio.
2. Check for viscous drag...
a. Before starting the engine, rotate the fan and clutch assembly by hand. It should have some viscous drag, but it should turn smoothly during the full 360� of rotation.
b. Replace the fan clutch if it does not turn smoothly or does not turn at all. Refer to the Dealer Master Parts Catalog for correct parts usage. Refer to the appropriate Service Manual, Section 03-05, for service details.
c. Replace the fan if there are only cracks.
d. If this is not the concern, go to Step 3.
3. Check for lack of viscous drag...
a. If the fan clutch spins with no viscous drag when it is cold, and it has not been run for an hour or more, it should be replaced. Refer to the Dealer Master Parts Catalog for correct parts usage. Refer to the appropriate Service Manual, Section 03-05, for service details.
b. If this is not the concern, go to Step 4.
4. Check for excessive fan clutch bearing clearance (cold fan clutch)...
a. Hold the tip of the fan blade between the thumb and forefinger.
b. Lightly pull toward the radiator, then push toward the engine. 
c. Repeat the motion several times.
* The total rocking movement at the end of the fan blade should be 2/10" (5.1mm) or less when no more than eight ounces of force is applied.
* A force greater than eight ounces may deflect the fan blade with erroneous results.
d. Replace the fan clutch if more than 2/10" (5.1mm) of movement is observed. Refer to the Dealer Master Parts Catalog for correct parts usage. Refer to the appropriate Service Manual, Section 03-05, for service details.
e. If this is not the concern, go to Step 5.
5. Install a temporary engine tachometer if the vehicle is not equipped with a tachometer.
NOTE: DURING THE FOLLOWING TESTS, BE SURE TO MONITOR THE ENGINE COOLANT TEMPERATURE BY THE TEMPERATURE GAUGE IN THE INSTRUMENT CLUSTER. SHUT OFF THE ENGINE IF THE TEMPERATURE RISES ABOVE THE MAXIMUM RECOMMENDED LIMIT FOR THE ENGINE OR IF COOLANT IS DISCHARGED OUTSIDE THE SYSTEM. THE TESTS CAN BE RESUMED USING THE FOLLOWING PROCEDURES AFTER THE COOLANT TEMPERATURE DROPS TO A NORMAL OPERATING LEVEL.
NOTE: IF THE HOOD IS LEFT OPEN, THE FAN NOISE MAY BE EASIER TO HEAR.
WARNING: DO NOT STAND IN LINE WITH THE FAN.
6. Start the engine.
7. Check for fan disengagement and be aware of the following operational characteristics.
* The fan clutch may be engaged when the engine is first started. This will be apparent from the noise level of the fan which has a distinctive roar.
* The fan clutch engagement is due to the viscous silicone fluid draining back and filling the gap between input and output components.
* Running the engine at a constant speed of about 2000 rpm should pump the fluid back to its reservoir, disengaging the fan clutch after no more than five minutes.
* As the fan speed declines, the noise will drop off to a level inaudible to most observers.
a. Continuing the test, If the fan clutch does not reengage after five more minutes at 2000 rpm, the fan clutch should be replaced. Refer to the Dealer Master Parts Catalog for correct parts usage. Refer to the appropriate Service Manual, Section 03-05, for service details.
b. Repeat the test procedure after fan clutch replacement to confirm the fix and to assure customer satisfaction.
c. If this is not the concern, go to Step 8.
8. Stop the engine.
Cut and install a piece of cardboard large enough to cover the front of the radiator with a six inch diameter hole in line with the fan clutch.
If it is not possible to install the cardboard directly against the radiator, attach it to the A/C condenser.
9. Start the engine.
a. With the gas engine at 2700 to 3000 rpm or diesel engine at 2100 to 2300 rpm, the vehicle temperature gauge will rise steadily as the engine warms and then appear to level off for a short time when the thermostat opens.
b. Make note of the temperature gauge position when the thermostat opens. The engine coolant temperature will continue to rise until the fan clutch engages.
10. Check for fan engagement...
a. Continue to observe the coolant temperature gauge. As the fan clutch engages, the fan noise will continue to increase and then level off at full engagement. The fan clutch may cycle off-and-on a few times during the initial engagement.
b. If the fan clutch does not engage before the maximum indicated safe operating engine coolant temperature is reached, it should be replaced. Refer to the Dealer Master Parts Catalog for correct parts usage. Refer to the appropriate Service Manual, Section 03-05, for service details.
c. Repeat the test procedure after fan clutch replacement to verify the fix and to assure customer satisfaction. The rate of rise of the coolant temperature will slow down after clutch engagement, but it will continue to rise as long as the radiator remains covered.
d. If this is not the concern, go to Step 11.
11. Check for fan disengagement...
a. After completion of the above tests, shut off the engine.
b. Remove the cardboard cover from the front of the radiator.
c. Restart and return the gas engine to 2700 to 3000 rpm or diesel engine at 2100 to 2300 rpm, continuing to watch the coolant temperature which will begin to decrease. The fan rpm will drop to a reduced noise level where it was before the cycle began which indicates that the fan clutch has disengaged.
d. If the fan clutch remains engaged and the coolant temperature has dropped below the thermostat opening temperature (as noted in Step 9) for at least five minutes, the fan clutch should be replaced. Refer to the Dealer Master Parts Catalog for correct parts usage. Refer to the appropriate Service Manual, Section 03-05, for service details.
e. Repeat the test procedure after fan clutch replacement to confirm the fix and to assure customer satisfaction.

OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS:
Eligible Under Bumper To Bumper Warranty Coverage For 1992 Models, Basic Warranty Coverage For All Other Models

OPERATION DESCRIPTION TIME
921514A Diagnosis Only - F-Series And Bronco 0.6 Hr.

fanclutchtest.jpg
fanclutchtest.jpg | Hits: 7484 | Posted on: 1/25/06 | View Low-Res

 

TSB 92-15-14 Fan Clutch Diagnosis

Screenshot_20190327-074855.jpg

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Hi All,

Just getting around to dealing with this again...

Good news and bad news...

Good news is I think a lower temperature thermostat fixed the erratic temp gauge issue, I installed a 180' thermostat today and it seems to have fixed the issue ( I previously was using a 192' thermostat as recommended by the Ford Dealership). Before the temp was all over the place now seems to rest on the "O" in "NORMAL" with slight variations...although I have yet to test it on a big hill (will do sometime this week). Not sure why they recommend the 192', that thermostat caused me nothing but headaches (I think I might need to swap that back in again before my next smog check though).

Bad news is when I went to change out my Temperature gauge sender, I buggered up the brass 6-point top of it and now can't get it out , stuck good with nothing left to get a socket on.

Any suggestions?

Thanks in advance

Edited by tjg8675

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Yo tjg,

This often happens.  Use penetrating oil or make your own w/acetone (or nail polish remover) and ps fluid or auto trans fluid, 50/50 mix. Let it soak in for 20 minutes.

Tap around the brass body.

Most use a slightly smaller socket to tap into place. Or a tool similar to a Bolt Extractor https://www.amazon.com/Tools-Power-Grip-Extractor-7-Piece-394100/dp/B000EF1EHY/ref=asc_df_B000EF1EHY/?tag=hyprod-20&linkCode=df0&hvadid=309763890402&hvpos=1o1&hvnetw=g&hvrand=13312005223394683489&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9003904&hvtargid=pla-423287065638&psc=1

Our former local MOM and POP parts store would loan it out to regular customers. Now, the chain store owners quit helping. OTC automotive tools seem to dwell on recent years and current. Ford model years.

Blazenxlt did this;
PICT0011.JPG
pointing right on the old one, kinda a bitch to get to.
PICT0007.JPG
new unit
PICT0002.JPG
➡️old one out, took the trusty dremel to it so I could fit a rachet on it brownbag.gif
PICT0001.JPG
new one in."

In past, some mechanics would use a Dremel remove some brass to fit a smaller socket on.

 

"Use a sensor safe liquid thread sealant to coat the threads before installation.

Using a tape type of sealant may electrically insulate the sensor not allowing the gauge to register.

Install a new sensor.Tighten the 6-14 ft. lbs. (8-19 Nm) using a box-end wrench or sending unit pressure switch socket.

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Hi All,

Thanks for the info Miesk5 gonna work on that soon,

Had a weird issue on my way to and back from work today :(

I was heading to work traveling about 40 mph down the road when the engine started running rough and I looked down at the instrument panel and the check engine light was on,  about 3 seconds later check engine light turned off and engine ran normal the rest of the way to work.

On my way home from work it started up ok but just down the street (maybe 1/8 mi) I was slowing down approaching a red light to stop and engine would not settle down to idle (stuck at about 1200rpm) and check engine light was on again. I put it in neutral and blipped the gas to see if it would unstick the high idle but didn't work, a couple seconds later the idle started jumping erratically from 1200rpm to below regular idle (about 500rpm) with no pedal input after doing this a couple times the engine stalled. I restarted it and check engine light was off and idle was normal so I proceeded cautiously. A little bit further down the road the erratic idle came back briefly along with a blinking check engine light (not steady blink, seemed to blink in time with the erratic idle) then went away.

I made it home with no further issue after a stop for food and checked the KOEO and the KOER for codes and all I got was 111 and 10 (pass) on both tests.

I'm wondering if this has anything to do with the recent change to the lower temp thermostat, could that be messing with the computer? (I noticed the temp gauge needle was below the "N" of NORMAL on both occasions, also it was a bit cooler today than it has been since the thermostat change)

The symptoms also seem similar to an issue I had a couple years ago (Feb 2017) with the IAC where the idle would stick when slowing down approaching red lights, but did not throw a check engine light, I replaced IAC with a motorcraft replacement and has been good until today.

Anyways I appreciate any help you can give

Thanks

TJG

 

Edited by tjg8675

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Yo TJG,

Let's rule out the t'stat for now until we clear up the idle issue.  

Try unplugging the Idle Air Control (IAC)
5.8l-dist.jpg
Location pic by Steve
Testing..
"First let me say this little thing has many names. But they all talk about the same item under the hood. Here all the names I've had the torture of learning throughout the years:
•Idle Air Bypass •Idle Air Control •Idle Speed Control •Throttle Bypass Air •Idle Bypass •Inlet Air Controller 
•Inlet Air Bypass •Intake Air Bypass •Intake Air Control.
This is really easy to test. First as with all problems you should gather the trouble-codes from the computer. Follow the codes for testing and repair. If you get a code that points to a problem with the IAB start the vehicle and bring the engine up to operating temperature. Allow the engine to idle without any driver input to the throttle or pedal. Go under the hood, and disconnect the electrical connector to the IAB. If the engine begins to stubble or stalls the IAB is functional and does not need to be repaired. If the engine idle does not change you should remove the IAB for inspection.
The IAB can pass and still need repair, or it can fail and not need replacing. The plunger and internal spring can get clogged with dirt and oil. This will slow down the air flow and not allow the IAB to function properly. Remove the IAB and clean it. There are 2 halves to the IAB, and you can not buy just one half, but you can take it apart to clean it. But if the internal solenoid is faulty the IAB needs to be replaced." By Ryan M.

IAC  Cleaning by Bobby (blue) in a 93 @ http://www.supermotors.net/registry/3982/17193-2


...
This is by Nelbur; "I have spent some time this week trying to set up an air bypass around the IAC valve by cutting away some of the gasket between the IAC in and out air holes, rather than pay big bucks for Fords spacer kit. I cut away the center of the original IAC gasket from the outside of each hole to the outside of the other hole, giving about 1/2" gap for the air to pass through. I noticed an immediate improvement in the engines starting behavior, but it would still die occasionally.

For most of my trucks life it has been dying when it was started hot. It would rev up and then drop the idle so low it would die unless I would catch the idle with the accelerator. It would never die when cold as the IAC would keep the idle speed up, and it never died at stop lights. Now it's worst situation seems to be when it has been shut down for a half hour or so, and restarted. I wonder if the heat soak is fooling the ETC into thinking the engine is warmer than it really is.
I decided that more improvement could be had if I had a thicker gasket, because the original IAC gasket was very thin (0.018"). I had some 0.030" gasket material so I made my own with the same 1/2" cut out. This gave enough bypass to noticeably raise the idle speed and almost eliminate the dying. After maybe 50 starts in the last few days, it only died twice. After so many years of catching it with the accelerator it is darned hard to leave my foot off it. It is clear to me that by trial and error one can tune the air bypass without the need for the expensive Ford kit. I may combine the two gaskets for more bypass, but the idle is about as fast as I would want now, especially for driving in snow."

Nelbur mentioned this Ford kit in..Idle Air Control (IAC) Sludge; Poor Idle TSB 91-25-07 for 85-92 Bronco & F Series & many others; "...Hard cold starts, hesitation and stalls on initial start-up or during idle or decel may be caused by sludge in the throttle body and/or idle by-pass valve. Sludge deposits or oil film on the throttle body bore and plate or the idle air by-pass valve may cause one or more of the following conditions. Hard Cold Start, Stall On Initial Start-Up, Stall During Idle, Stall During Decel, Rough Idle, Rolling Idle, Hesitation During Acceleration. A new idle air by-pass service kit (F2PZ-9F939-A) is now available for service use to correct sludge contamination concerns of the throttle bore and plate only. It eliminates the need to clean the majority of past model throttle body applications. Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years..."

Buy another Motorcraft IAC in event it needs to be replaced.

Check for vacuum leaks see my test, post #11

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Hi Miesk5,

thanks for the info

I started it up this morning and about 5 seconds after startup the check engine light came on and rpm's rose to and stuck at 1200 same as yesterday, I backed out of my garage and noticed that the exhaust smelled VERY rich, I put it in drive and tried to move but had NO power (it was like it was in 4th gear, but was actually in 1st). I then stopped and shut it off and restarted but check engine light was on again and still had no power (in hindsight I should've checked codes at this point but didn't). I drove to the end of my driveway, stopped and the engine stalled. I restarted it and the check engine light was off and power was restored. I then drove to my mechanics shop a few miles away with no issue and checked codes again, same result as yesterday, KOEO - pass and KOER - pass.

From what I can tell the issue goes away once it warms up to operating temp, my mechanic does not think the lower temp thermostat is related to problem and suggested maybe the coolant temp sensor/sending unit might have something to do with it (not the temp gauge sender, the other one)

I unplugged the IAC and the rpm's dropped a bit so I think that is a pass

Wondering if it is either the coolant temp sensor/sending unit, ACT or an issue with the computer ???

 

Thanks again for the help

Edited by tjg8675

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Yo T,

Your mechanic may be right! 

ECT Sensor test;

  • Unplug the harness connector.
  • First, check the signal voltage at the connector with the key on, engine off. Should be approximately 5.0v.
  • Then, check the resistance of the sensor cold. Should be between 58,750 to 40,500 ohms.
  • Plug in the harness connector and warm up the engine to normal operating temperature.
  • Then, unplug and check the resistance of the sensor hot. Should be 3,600 to 1,840 ohms.
  • See more info in attached docs.GL!

20181227_101928.jpg

20181227_094749.jpg

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OK thanks Miesk5,

I have a new ECT on the way from Ford will be here monday, was cheap and easy enough to just replace, but I'll run the tests later today anyway

I was also reading about high idle/check engine light issue here https://www.fullsizebronco.com/forum/21-noobie-bronco-tech-questions-flame-free-zone/100038-95-bronco-5-8-high-idle-problems.html he said it might be ACT although he had a code 133 (my book doesn't even show a 133 ???)

Edited by tjg8675

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Yo T,

Right, 133 doesn't apply to our Broncos.

DTC 113  Does; The sensor signal is greater then the Self Test max volt of 4.6 or higher - "...indicates that the corresponding sensor signal is greater than the Self-Test maximum. The maximum for ECT and IAT sensors is 4.6 volts. Possible causes: Open in harness (IAT or ECT), Faulty connection, Faulty sensor, Faulty Powertrain Control Module (PCM)..." 
Source: by miesk5 at FSB

as does DTC 112 to 114, (ACT prior to 92 or IAT) Troubleshooting & Possible Causes; Codes 112 to 114 will set a IAT sensor code in the EEC, remove and inspect the sensor it could get contaminated by engine oil , K&N oil or dust. Clean the sensor with isopropyl alcohol. If the sensor still fails replace the unit. by me

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Hi Miesk5,

Thanks for the info

A little off the topic but ...Do you have the correct part number for the Ignition Control Module for my 1995 Bronco 5.8l with CA emissions?

Please correct me if I am wrong, but from what I understand there is some confusion surrounding this part due to an error in Ford's part listing to aftermarket vendors which apparently was never corrected.

When I search O'reilly's, Summit Racing, Amazon, etc. they all direct me to p/n DY1075 which is a grey icm, my Bronco most definitely has a black icm which I think the replacement is p/n DY1077 but shows as incorrect part or not listed as available for my vehicle in the stores databases, Amazon sellers will not even ship a DY1077 to me in California due to Ca Air Board restrictions.

Thanks for the help

TJG

 

 

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Yo T,

ignition control module DY 1077 from Rock Auto is Genuine Ford Motorcraft®⚠️


Remote Mount Black CCD "Computer Controlled Dwell" ICM
Ford Bronco -
remote_TFI_harness2.gif[/IMG]
Motorcraft - DY1077 (supercedes DY679, DY667, DY645)
Ford - 5U2Z-12A297-D (supercedes F1PZ-12A297-A)
Wells - F139
Niehoff - FF413
BWD - CBE40
Standard - LX-241
NapaEchlin - TP29
Delphi - DS10056
Transpo - FM544

I am fairly confident in my research, except for the non-Bronco Distributor Mount Black CCD ICM. I do not believe that the Bronco ever came with this so another Ford ICM is subsituted. What I looked for was a 6+3 Pin "Black" Ford TFI Ignition Control Module and crossed referenced it to other brands." by Seattle FSB @ https://www.fullsizebronco.com/forum/23-technical-write-ups/183668-ford-tfi-ignition-control-modules.html

Next is to ensure Motorcraft® parts for sale are Genuine Motorcraft and not knock-off junk.

On 21 May, 2019 I purchased a 96 Ford Bronco 5.0 ignition control module, Motorcraft® DY 1077 from Rock Auto.
I received it 23 May and noticed the usual Motorcraft® logo wasn't impressed on it.
Bronco&id=478282&attachment=3&user=2&con

The box looked the same as what I have purchased in past from our local Ford dealership.

I e mailed Ford Global Brand Protection and asked, "is this is a genuine Mototocraft part?"
Here's the reply;
"After reviewing the information you provided, the part you purchased appears to be genuine. The OE current model part does not have a Motorcraft/Ford logo on it and looks like the part in your photo. Since the vehicle model year for this part is very old the supplier of the part most likely has changed. Also we have not had any prior issues with Rock Auto selling non-genuine parts."
Lisa W. 
Ford Motor Company
Global Brand Protection
"What Is Global Brand Protection?
The Global Brand Protection group exists to protect the consumer by ensuring high quality original equipment parts are used in your vehicle that are recommended by Ford Motor Company. Counterfeit products potentially compromise consumer expectations because they do not meet Ford Motor Company’s rigorous testing and quality control standards. 
Global Brand Protection focuses on:
Preventing the distribution of and removing counterfeit parts from the marketplace
Ensuring that the company’s trademarks are used appropriately
Maintaining the integrity of the sale and distribution of Genuine Ford parts..." 
Ford | Global Brand Protection

BTW, it is the aftermarket that has screwed up the ICM year, make, model etc mess, not Ford.?

Finally;

Section 03-07A: Ignition, Distributor
1996 F-Series and Bronco with Gasoline Engines Workshop Manual
REMOVAL AND INSTALLATION

Ignition Control Module

Removal

  1. Remove two screws retaining ignition control module (ICM) (12A297) heat sink assembly to left fender apron.

  1. Disconnect harness connector from ignition control module.

  1. Remove two screws retaining ignition control module to heat sink and remove ignition control module.

Installation

  1. Coat ignition control module baseplate with silicone compound, approximately 0.0179mm (1/32-inch) thick. Use Silicone Dielectric Compound (WA-10) D7AZ-19A331-A or equivalent meeting Ford specification ESE-M1C171-A.

  1. Position ignition control module onto heat sink and tighten two retaining screws to 1.2-1.8 Nm (11-16 lb-in).

  1. Install ignition control module heat sink assembly on left fender apron using two retaining screws, and tighten to 9-14 Nm (80-124 lb-in).

  1. Connect wiring to ignition control module.

    b5728a.gif

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Posted (edited)

 Hi Miesk5,

Thanks for the info on the icm, I stopped by my local Ford dealer parts dept today to pick up my new coolant temp sensor and had them lookup the icm for my bronco, using my VIN # they told me the icm for my bronco is DY1075 (the grey one). I told him I'm pretty sure the one I need is the DY1077 (the black one), since the original one is still in my truck and is black. The parts guy didn't argue with me and looked up the DY1077.  They wanted $210 for it so I told him I can find it somewhere else for much less, but this got me thinking why the other places are so much cheaper (I know the dealer has crazy markup but that is ridiculous) $136.99 at summit racing, $116.79 at rockauto,  $64.19 at Amazon, $79.99 at autozone. The amazon and autozone must be knockoffs at those prices!!

I guess I need to pull out the one in my truck and get the part # off it just to be sure but am finding this whole debacle frustrating, makes me wonder what other parts are mis-listed or could be cheap knockoffs

Probably going to order from Rockauto (once I check on the original part #) since they have best price and seem reputable

Thanks agian

TJG

Edited by tjg8675

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Yo T,

Thanks! Now I know Ford dealerships have same mistaken ICM parts issue as the aftermarket suppliers.

I checked ROCK AUTO yesterday for your CA emissions 95 Bronco 5.8 and  they have Wells - F139 listed in the Info section for 6H1086 for alternate OEM part numbers.

Let me know on your part number.

 

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