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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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