Engine overheating

dant01 · Jun 27, 2020

Have a 92 with ford motorsport 3 row rad. Boiled over last year in traffic. Gauge has never gone past second dash in 28 years. Changed out fan clutch last year seem to take care of the problem. This summer it is heating up again. the fan clutch has a little resistance when cold and hot. Shouldn't it be stiff while spinning while hot? Cools down at speed but gauge does move a aful alot when driving. I did just replace sending unit, I do trust the gauge. Pulled water pump last year also just to verify blades were in tact and pining with shaft. I noticed last nigh bubbles in the coolant when hot. Possible headgasket could my fan clutch be bad again?

08GT500 · Jun 28, 2020

Hi,
Sounds like you may have more than one problem, I’d still confirm with a mechanical gauge if no other evidence of high temperatures exist. Thermostatic clutch ass’y should be spinning the fan with vehicle at rest and low speeds, & when hot- until increased vehicle speed and external airflow picks up.
If the temperature is leveling off at higher vehicle speeds, that would suggest temp. should also be maintained at lower speeds with adequate airflow across the radiator which the fan should be providing.
That sounds as if the thermostatic clutch assembly may not be functioning correctly.
But, it seems it’s fighting abnormally hard to drive temperatures down, as you described.
I Suggest first acquiring a Hydrocarbon test kit to prove if you indeed have a combustion leak path into your coolant.
A small leak may not always blow the pressure cap, I’ve seen radiators blown wide open as a result of this. Test or replace the Cap for safety if a leak is detected in addition to other repairs.
If no HC’s are present, refocus your efforts on the cooling system, thermostat, shrouding, clutch fan ass’y, obstructed engine coolant passages, lean conditions, spark timing, etc.
Please post your findings, and any other questions.
Best of luck!
-John

General karthief · Jun 28, 2020

I agree with John, not that I have any idea what he usually is say'n but I can get the drift of it
Now about that stock gauge: every time you change the sender it will react differently, the stock gauge is what I call 'a best guess', add an aftermarket mechanical gauge even if it is temporarily zip tied to the wiper arm so you know what the temp actually is and where it reads on the stock gauge.

08GT500 · Jun 28, 2020

HemiRick · Jun 28, 2020

Fan clutch should noticeably tighter when hot, if not its bad. Over the years I've had 2 small head gasket leaks on my Mustang. When started it would miss for a minute on the leaking cylinder.

dant01 · Jun 29, 2020

hydrocarbon test was negative found a severe duty fan clutch for 38.00 may just buy it swap out the lmr unit checked last nigh cold to hot fan has a little resistance no difference hot or cold

General karthief · Jun 29, 2020

Does the extreme duty clutch have a spring on the face?
I try to get the replacement with the spring, they 'lock up' if the unit stops working.

dant01 · Jun 29, 2020

General karthief said:
Does the extreme duty clutch have a spring on the face?
I try to get the replacement with the spring, they 'lock up' if the unit stops working.

yes it does

08GT500 · Jun 29, 2020

Glad to hear negative HC test. This the one you have installed now?

Mustang Fan Clutch (85-93) 5.0 - LMR.com

Trying to save more power while still keeping your Mustang cool? A Mustang Fan Clutch is perfect for you!

lmr.com

-John

dant01 · Jun 29, 2020

08GT500 said:
Glad to hear negative HC test. This the one you have installed now?

Mustang Fan Clutch (85-93) 5.0 - LMR.com

Trying to save more power while still keeping your Mustang cool? A Mustang Fan Clutch is perfect for you!

lmr.com

-John

Yes

dant01 · Jul 7, 2020

replacing the clutch didn't change things. Its a lot more robust looking clutch than the lmr unit

08GT500 · Jul 14, 2020

dant01 said:
replacing the clutch didn't change things. Its a lot more robust looking clutch than the lmr unit

Hi,
Ever nail down your overheating issue?
I’d not listed the lower air deflector that directs airflow up into the Radiator/A/C Condenser, helps at those lower speeds quite a bit. Didn’t want to leave you hanging if the issue remained & you’re working at it & wanted suggestions.
Best!
-John

dant01 · Jul 14, 2020

Yes all shields are in place. I flushed this weekend to no avail. Condenser and Radiator fins are clean and open. I am a bit stumped, I ported and polished the head a couple of years ago. I am going to pull motor this winter and dig deep. They are old school J302 heads, I have heard that coolant passages are prone to cracking.

08GT500 · Jul 14, 2020

Hi,
Well..that’s certainly sounds like a possibility.
There is one remaining last ditch effort to check with the motor assembled in the car.. Externally pressuring the Blocks Coolant passages using compressed air laden with a tracer dye will help you either way by revealing if a fissure exists, and where the actual leak path is if you need do a teardown.
No oil in coolant or vise versa, heater cores clean, not blowing steam, no loss of coolant, motor runs as it should aside from fighting this Temp rise. Glad to assist if you want to try it. Either way, best of luck!
-John

Engine overheating

dant01

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08GT500

General karthief

wonder how much it would cost to ship you a pair

08GT500

HemiRick

I'd be looking at jacking under the house

dant01

Member

General karthief

wonder how much it would cost to ship you a pair

dant01

Member

08GT500

Mustang Fan Clutch (85-93) 5.0 - LMR.com

dant01

Member

Mustang Fan Clutch (85-93) 5.0 - LMR.com

dant01

Member

08GT500

dant01

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08GT500

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Engine overheating

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wonder how much it would cost to ship you a pair

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