Tonwoo28

Alright,
I've installed a new Stewart Water Pump, a new Radiator, a new Thermostat, new hoses, and by-passed the Heater Core. The car is over-heating. This only happens in heavy traffic, or when the A/C is on. Where I thought the Water Pump was squealing I may have been wrong. Because, now that the pump is replaced, I'm still hearing it. Sounds like the A/C compressor may be the blame. The only odd part is, when I turn on the A/C the squealing stops. It's very hard to tell. Also, when the car gets above 200 and I shut it down, coolant immediately starts to come out of the overflow tube (not hooked to reservoir). My thoughts point toward the thermostat, but after working this problem so long I'm just not sure anymore. Any suggestions?

jerryp58

You should be able to check the thermostat without removing it. With the engine cold, remove the cap, start the engine, and once it gets up to operating temp (the temp of the thermostat), you should see the coolant start to flow. If not, you've got a thermostat problem.

If your A/C compressor has problems (not just a squealing belt), I suppose it could be causing the engine to work harder :confused:

The A/C condenser isn't clogged with debris, is it?

Did you flush the cooling system before the new radiator? That might have helped any blockages in the engine.

What type of fan do you have?

What temp are you getting up to? A little over 200 doesn't seem like it'd be to bad for FL.


[Modified by jerryp58, 4:53 PM 8/13/2003]

mrvette

First off, wiggle the fan blades from one end...fore and aft...if there is significant play in that hub, and especially if i'ts 'dirty' looking, there fluid is gone from the clutch...replace it....and IF you can, find a 7 bladed cooling fan for it....bolt on, from a junkyard....
you may want to change out the radiator, unless i'ts NEW and the largest one you can find to fit the car....overheating in traffic is one of 4 things....
radiator, airflow(fan-clutch) shroud, thermostat (gut the damn thing down to the restrictor ring and reinstall), OR possible the pump not putting out enough water....very rare...
unless you have a coolent leak.....and that last thing is a bear...I fought and fought over 3 years on and off, a porous radiator...I think aluminum does that, weeps, as opposed to pis s the stuff out, leaving a mark....

GENE

sb69coupe

What type of radiator did you install? What type of fan do you have? Is it a stock thermostatic fan clutch or something aftermarket? Are the correct seals in place between the radiator and core support? Do you have a fan shroud? If so, do you have the seals in place between the shroud and the radiator?

Does the car overheat at speed with the A/C on?

Overheating in traffic suggests that either:

1 - There is insufficient airflow through the radiator. Hence my questions above.

- or -

2 - The radiator cannot reject the heat fast enough. But since the car cools well at speed, I doubt this is the case. It could be that the radiator is marginal if the car still overheats at speed with the A/C on.

77Dream

How hot does it get? You said you shut it down when it gets over 200, How much over? 200 is not bad for traffic or AC use.

jlsru

I changed all the same things that you did on my 75 and it still ran hot.The very last thing I changed was the fan clutch and that fixed the problem.Good luck!

72ls5fla

For what it is worth .....

Be sure that you have a 15-16# radiator cap.
Be real sure it is holding pressure. If not, the water will boil at a lower temp, because of lack of temp.

As a rule with these here C3s, if it overheats in trafic, it can be crud between the rad and condensor, seals missing between the shroud and frame/radiatoe , a bad clutch unit, or the air dam under the car is bad, tourn, or missing.

Best I can tell (from variuos conversations) the thermo regulates the water circulation speed and volume. REAL important not to gut or remove. Use a 160 if it make you feel better, but kep one in the car. Also, air pockets will cause you abunch of grief. be sure the water level is full, ovefull is equally not good.

C3s are hot running cars. ine wil run 180-190 no air, 205-210 with air on.

Hope this helps some..

Bill :)

Tonwoo28

I did flush the system when I replaced the radiator. In fact, the radiator was replaced about 2 months ago. I didn't experience any problems until after the water pump replacement. However, the thermostat is from the radiator install. I didn't think it necessary to replace it again. I think you may be right about the thermostat. After allowing the car to warm up, with the radiator cap off, the coolant level never changed. If I replace it and it works I'll feel like an idiot, but a happy one.

Tonwoo28

Yesterday it went to 240 after driving it for 100 miles. The A/C was on for about 25 miles. Until the water pump started to fail, it ran about 190 - 195.

Tonwoo28

Is it possible for the thermostat to go bad without completely closing up. I can drive the car, tihout A/C, and it runs around 200. This is 5 - 10 degrees above what it normally runs.

bigvette1

It is not much work and not much cost, go get a new 180 t-stat like a Robert Shaw. Test it in the kitchen in a pan with boiling water using a thermometer to make sure it is opening at 180 and closing down when you cool the water to 180. Then go replace yours. This will eliminate this question.

I have gone through as many as 3 stants and Robert Shaws to get a good one that cycles at the proper temp. Don't trust them without testing.

Educate me - does an 80 use an aux. electric fan?



[Modified by bigvette1, 8:29 PM 8/13/2003]

Tonwoo28

No. It uses a clutch fan, and it appears to be working fine.

Tonwoo28

I always thought coolant flowed from the radiator thru the upper hose and into the engine. Now that I think about it, shouldn't that be the other way around. Otherwise, how else would the coolant reach the required temp in order for the thermostat to open? Am I right or wrong?

pillowmeto

I talk to a guiy at the local show last week w/ a blown ford engine in a mercuray. He said that at first his water pump was running to fast not giving the water suffcient time to cool. If the new pump has a smaller pully i could see how that would be to blame, also if its bigger it might be running to slow, just compare the pully sizes. It sounds like a fan clutch to me, i know my fan bloes rwal hard at idle, i had a tarp over the car cause it started to rain in a carb change. When we started her up there went the tarp. So the fan could be running below what it is supposed to be, but still running so you woulndt think much of it. Maybe eletric fans if nothing else works.

MAtt

whiteae

Over heating problems in Hawaii did the same drill your going through. After you switch the cap radiator and thermostat and the problem still there try a colder spark plug. I chased this bug for months when I returned to hawaii 85 degress or better every day the car now run 170 all day long. New to the site but not new to the game. :_dupe:

bigvette1

Your question about coolant flow is out of the intake manifold to the top of the radiator accross the radiator, out the bottom hose to water pump and back into the block.

68shark

Just two more items....seeing it's heavy traffic/Air con. use....is your car running lean or is your vac. advance not working properly? Either will have even the best cooling system struggling to cool the engine.

Tonwoo28

Thanks!