Coolant temperature too low

[Greg B]

My son's 89 Bronco with 5.0 is not getting warm enough.  Have recently replaced Coolant Temp Sensor, Thermostat, and Water Pump.  The fan clutch seems to have proper resistance.  The heat has never really blown hot only warm.  This is also causing a stalling issue when first driving.  Have to let warm up several minutes before no stall.  Temp gauge barely moves (I know they're not trusty) and coolant is not hot to touch with cap off, even after driving for a while.  Hoses coming from heater core through firewall are both warm and warmer than radiator hose.  Any suggestions?

 

[Greg B]

Would also like to add that the coolant level in radiator is full as well as in the reservoir.  No loss of coolant is evident when removing the radiator cap.  

 

[miesk5]

Yo Greg,

Welcome!

Likely perperpetrators 

[SIZE=10pt]Cooling fan inoperative; iggie[/SIZE]


Damaged thermostat.


Thermostat Installation, 5.0L/5.8L Shown




 





Item


Part Number


Description




1


8255


Water Outlet Connection Gasket




2


8592


Water Outlet Connection




3


391428


****** 5/16-18 x 1.25




4


8575


Water Thermostat




5


391430


***** 5/16-18 x 1.75




A


—


Insert with Copper Pellet Towards Engine




B


—


Tighten in Sequence Indicated in Text to
16-24 Nm (12-18 Lb-Ft)

• 
  CHECK THERMOSTAT OPERATION
  
  
• Remove water thermostat and check opening temperature as marked.. 192 degrees F
  
• Does water thermostat begin to open and become fully open at 192?
  
  
  
  
  Yes
  
  
  No
  
  
  
  
  REINSTALL water thermostat and CHECK temperature gauge operation as outlined in Section 13-01.
  
  
  REPLACE thermostat.
  
  
  
  
  

 

[miesk5]

Yo Greg,

My internet provider is acting up, so here is what I overwrote.

Thermostat is stuck open, damaged.

Here are the 1989 EVTM, Emissions & Pre-Delivery Manuals, Partial via mrnewland1 in Google Drive @
https://drive.google.com/drive/mobile/folders/0Bz1eScc6s4raOHd0WlVnMUw4WjQ?usp=drive_web
Slow scrolling so download for the table of contents, etc.

1989 Bronco Dealer Brochure @ 1989 Ford Bronco

Free registration for some wiring diagrams (86 through 96) and Technical Service Bulletins, (80 through 96), same as by Ford @ BBB Industries- Premium Alternators, Starters, Power Steering Products | TSB's & Wiring Diagrams

GL!

Al

 

[Greg B]

Much appreciated and thanks for the quick response.  I did notice fan looks to be going full speed when initially started though not knowledgeable enough to know if supposed to or not.  I do feel resistance when turning and when trying to spin by hand (obviously with truck off) it will not complete one full revolution.  I was afraid to admit that it might be the t-stat because the low coolant temp didn't occur until replaced.  I just hate to think i replaced it last week and now have to break into it again.  Again thanks for the info, the brochure and the add.  I am sure I will frequent this site!

 

[miesk5]

Yo Greg,

I forgot to ask if coolant to water mixture was ok. The approved coolant for Ford vehicles is a 50/50 mixture of water and Ford Premium Cooling System Fluid.

Fan Clutch Test by Ford:

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.

Minimum Fan Clutch Requirement Test — Cold

1.  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 can be done at home or at a radiator repair shop.

1.  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.
   

Fan Clutch Specifications




Engine


Vehicle


Equipment


Water Pump Pulley Ratio


Engine rpm Required to Run Water Pump at 3000 rpm


Water Pump Fan Test Speed


Water Pump Test Speed




Minimum Fan rpm at Disengagement Temperature


Minimum Fan rpm at Engaged Temperature




4.9L
(300 CID) I-6


F-150, F-350, F-Super Duty and Bronco


with A/C


1.28


2340


1200 @ 125°F


2200 @ 190°F


3880




4.9L
(300 CID) I-6


F-150, F-350, F-Super Duty and Bronco


Without A/C


.98


3960


1200 @ 100°F


2075 @ 165°F


3000




5.0L
(301 CID) V-8


F-150, F-250 Bronco


Manual Trans. — Standard


1.37


2580


1800 @ 140°F


2800 @ 200°F


3540




5.0L
(301 CID) V-8


F-150, F-250 Bronco


Manual and Auto. Trans. with A/C Auto. Trans. — Standard


1.37


2190


1400 @ 190°F


2450 @ 155°F


3000





..."

 

[Greg B]

Ok Al thanks for all of the info.  I did notice over the holiday both heater hoses were getting hot.  Way hotter than radiator hoses or even coolant for that matter.  I "primed" radiator hoses and coolant level went down minutely (several times) each time I added a little more coolant.  Eventually the coolant gets hot and upper and lower hoses get hot to touch but it seems like taking too long (15-20 minutes).  I put some cardboard in front of the fan and let idle for very long time and system seemed to get to normal operating temp.  Never got hot but odd thing is there was no real pressure on radiator hoses.  Yesterday with cardboard in place I drove to town (outside temp 56 degrees) and with the ol' untrustworthy temp gauge showing high side of normal truck did run hot and coolant sputtered out of overflow reservoir.  Once cardboard removed temp fell back to normal since it had been running.  I do see that coolant is  being pulled through radiator.  Thoughts?

 

[miesk5]

Yo Greg,

yw!

How did the t stat turn out?  And do you think it id one with wrong temp opening?

. If the heater hoses are too hot to hold, the thermostat is OK. If the heater water hoses do not get too hot to hold, replace the thermostat.

These pop up ads ****! Hard to avoid them when typing!!×
 

 

[Greg B]

Yes heater hoses get too hot to hold.  It takes forever but eventually the radiator hoses do too.  I went with the 195* OEM recommended T-Stat.  I'm stumped on this one.  Reading back through this thread I believe I've told you all i know to tell you.  What are your thoughts on the hoses not having any pressure until it finally reaches hot temp?

Thanks again!

 

[miesk5]

Yo Greg,

Could be a bad radiator cap.

Some stores will loan you a coolant pressure tester with cap adapter for a refundable deposit 

See instructionjs @ http://www.diesel-dave.com/vehic/manual/stj/stj33014.htm#extract_574

 

[muddrivermike]

Hey this may sound stupid but over the years of being a mechanic in the shops I have run across something somewhat like this. We had either another shop or customer install the wrong radiator. Its was one with more rows than what the vehicle originally had which caused the coolant to run too cool. Dont know if you know if the radiator has been replaced or not, but figured id throw that out there to you. the way around it was to put a HIGHER temp thermostat in to counteract it. Hope maybe this helps