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Thermostat malfunction?
#1
Last summer I purchased a theromstat/restrictor kit that was supposed to be correct for a 351C. It was a 195 degree stat. During the summer I had problems with Temp running hot while in heavy traffic - up to 220-225 degrees. Now that its cooler, the temp gauge never gets over 180-185, even sitting at idle for long periods. My guess is that the thermostat is faulty and never closes to allow the cooling system to function properly. Does this make sense? I ordered it from tmeyerinc/track boss products that was recommended on this site.
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#2
(12-20-2018, 05:59 PM)mbrew2 Wrote: Last summer I purchased a theromstat/restrictor kit that was supposed to be correct for a 351C. It was a 195 degree stat. During the summer I had problems with Temp running hot while in heavy traffic - up to 220-225 degrees. Now that its cooler, the temp gauge never gets over 180-185, even sitting at idle for long periods. My guess is that the thermostat is faulty and never closes to allow the cooling system to function properly. Does this make sense? I ordered it from tmeyerinc/track boss products that was recommended on this site.

1. did it run hot before you installed the t meyer t stat?

2. exactly what was included in the t meyer t stat kit?

3. how hot was the outdoor temp when it ran hot?

4. how far is your engine bored?
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#3
(12-20-2018, 06:31 PM)barnett468 Wrote:
(12-20-2018, 05:59 PM)mbrew2 Wrote: Last summer I purchased a theromstat/restrictor kit that was supposed to be correct for a 351C. It was a 195 degree stat. During the summer I had problems with Temp running hot while in heavy traffic - up to 220-225 degrees. Now that its cooler, the temp gauge never gets over 180-185, even sitting at idle for long periods. My guess is that the thermostat is faulty and never closes to allow the cooling system to function properly. Does this make sense? I ordered it from tmeyerinc/track boss products that was recommended on this site.

1. did it run hot before you installed the t meyer t stat?

2. exactly what was included in the t meyer t stat kit?

3. how hot was the outdoor temp when it ran hot?

4. how far is your engine bored?
When I bought the car it had a bad radiator that leaked. I replaced the radiator with a new factory style 3 core. I was still working on the car so not driving every day and didn't notice a problem.

The kit included a 351C correct style thermostat and the brass machined restrictor.

During summers down hear temps run 90's to near 100's.

Engine was rebuilt 13000 miles ago by PO. Have no spec's on internals. Just invoices.

Problem first surfaced this past summer after I installed new A/C system and started using the car as a everyday driver.

I replaced the thermostat just as precaution/preventive measure when I replaced the radiator and all hoses.

Temps now in Mobile range from 40's to mid 50's. Seems that engine should warm to 195 thermostat setting regardless.
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#4
The thermostat is supposed to be fully open at the advertised temperature, they begin opening 10°, or so, sooner.

How old is the water pump? The impeller is made of steel and can rust.

Do you have the correct fan shroud and diameter fan? Fan belt properly adjusted and tightened?



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#5
What exactly does this mean?

"Temps now in Mobile range from 40's to mid 50's. Seems that engine should warm to 195 thermostat setting regardless."


Exactly what radiator did you install?
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#6
If the temp goes up in traffic and then goes down to the rated t-stat temp at highway speeds it probably isn't a t-stat issue. It is more likely a cooling capacity and/or airflow issue.

My guess is the newly added a/c condenser is restricting airflow through the radiator at idle. If that is the case you need to find a mechanical fan that moves more air or switch to an electric fan.

All this assumes that you have a properly fitting fan shroud, the fan the proper distance from the face of the radiator and the ignition timing set correctly.

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.
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#7
The car was originally a factory A/C car. I replaced the factory unit with a modern system from Classic Auto Air. I replaced the radiator with a copper factory replacement. It has the original factory A/C shroud and fan.

I had posted here back then about overheating and suspected not enough air flow in traffic. Actually planned to install electric fans next summer. It was confusing to me that since it was originally a factory A/C car why the problem should surface when I replaced the factory system.

My thermostat concerns surfaced again now that the air temp is in the 40's to high 50's but the engine doesn't warm up to near the thermostat rating.

Excuse my lack of understanding about how the cooling system works, but I thought that in cooler weather the thermostat should remain closed until near its rating, then it would open and then cycle on an off as needed to maintain  that temp. I thought that in hot weather the same thing would happen and when it opened, cooler water from the radiator would cycle it closed, giving the fan/radiator time to cool the fluid some and on and on.

If it stays open all the time once it reaches near its rating, why run one at all?
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#8
(12-21-2018, 09:22 AM)mbrew2 Wrote: The car was originally a factory A/C car. I replaced the factory unit with a modern system from Classic Auto Air. I replaced the radiator with a copper factory replacement. It has the original factory A/C shroud and fan.

I had posted here back then about overheating and suspected not enough air flow in traffic. Actually planned to install electric fans next summer. It was confusing to me that since it was originally a factory A/C car why the problem should surface when I replaced the factory system.

My thermostat concerns surfaced again now that the air temp is in the 40's to high 50's but the engine doesn't warm up to near the thermostat rating.

Excuse my lack of understanding about how the cooling system works, but I thought that in cooler weather the thermostat should remain closed until near its rating, then it would open and then cycle on an off as needed to maintain  that temp. I thought that in hot weather the same thing would happen and when it opened, cooler water from the radiator would cycle it closed, giving the fan/radiator time to cool the fluid some and on and on.

If it stays open all the time once it reaches near its rating, why run one at all?

The thermostat maintains minimum engine temp. Once it is open the cooling system capacity determines max engine temp. If you don't run a thermostat the engine will be slow to warm up and in the winter or at highway speeds may operate at too low a temp which can reduce gas mileage, cause drivability issues and increase engine wear. A street car should not be run without one.

Sorry, I misunderstood about the A/C. I thought it was a recent addition.

Its easy enough to test the thermostat in a pot of water on the stove with thermometer if you still think that is the issue.

You may also want to check your timing. Insufficient ignition advance will significantly increase combustion temps.

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.
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#9
(12-21-2018, 09:22 AM)mbrew2 Wrote: The car was originally a factory A/C car. I replaced the factory unit with a modern system from Classic Auto Air. I replaced the radiator with a copper factory replacement. It has the original factory A/C shroud and fan.

I had posted here back then about overheating and suspected not enough air flow in traffic. Actually planned to install electric fans next summer. It was confusing to me that since it was originally a factory A/C car why the problem should surface when I replaced the factory system.

My thermostat concerns surfaced again now that the air temp is in the 40's to high 50's but the engine doesn't warm up to near the thermostat rating.

Excuse my lack of understanding about how the cooling system works, but I thought that in cooler weather the thermostat should remain closed until near its rating, then it would open and then cycle on an off as needed to maintain  that temp. I thought that in hot weather the same thing would happen and when it opened, cooler water from the radiator would cycle it closed, giving the fan/radiator time to cool the fluid some and on and on.

If it stays open all the time once it reaches near its rating, why run one at all?

Ok, I'm still confused.

It sounds to me like you are now saying that it did not run hot before you changed any parts, is this correct?

Is your water pump stock?

Is your t stat bypass plate firmly in place?

You did not tell me exactly what radiator you installed so I can't help you there but you can take a photo of the top of the rad rubes, and measure the thickness of the core (not the tanks) then the spacing of the tubes from center to center.

As far as the engine temp not getting up to the t stat rating in cold weather, you did not tell us exactly what temp it does get to, but yes, it is possible the t stat is stuck open, but this is an easy thing to check.


Your understanding of how the cooling system works is correct, but there is also a "bypass" system on most cooling systems that allows some coolant to continuously flow thru the system all the time but this is usually a passage that is only around 1/" in diameter at the most.

The more info you supply, the better.


Also tommy k's timing suggestion is good, and I can tell you how to set it close to the optimum level for your particular car if you want, but my guess is that even if your timing is off, it will not be causing all of your problems, so you will still likely need to address another area as well.

.


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#10
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