i just went on a trip to old town on fri on my way there and back my car would run around 220 - 240 when i would go to pass someone the valves in my engine would rattle. i checked the oil is full , the water is not low. the water pump is working fine. i see a good circulation of the water when i take off the cap.i have a 1978 c-3

 

Fan clutch, chin spoiler, timing, foam seals around radiator? Could be any or all of these...........or none of them.
Good luck,
Greg

 

Engine "ping" is usually a result of too much advance timing and is experienced under just the exact conditions you describe. Try checking your timing.

 

with a stock radiator, what is the "normal" operating temp range? My 78 runs about 220, or whatever EXACTLY straight up and down on the gauge is...is that ok or should I worry?

 

Mine does not exeed 210 even when punishing it quite heavily - your figure sounds too much

 

My 79 runs about runs about 180-190 with a 180 thermistat and that is with both motors new motor has 165 miles on it. Try a different thermistat since its easy to change and get to. Good luck dont run it hot till you figure it out.

 

would a aluminum rad. make it run any cooler and why. they say my car should run a 195 thermastat does it hurt to run a 180 or cooler one

 

This might be a bandaid to the problem... check you timing and carb adjustments first...did wonders for me.

after adjustments it ran maybe 10-12 degrees cooler


Good luck,
Jim

 

An aluminum radiator will definately help out to run cooler, but I do not think that you should need it. I am running a stroker 385 with 10.5:1 compression and full headers and I have absolutely no problem with overheating using the stock radiator. I did put in a new 180 thermostat but otherwise it is the stock radiator and it runs at about 180-190 all the time. Something else is wrong to be running that hot.

 

Pull the stat, and run it for a week...if it stays nice and cool, drop a 160 in it...also, an engine running "too hot" will knock under load, so be careful...

 

In addition to the above suggestions, Your rad may be in need of a flush as well, try a system flush and see if there is a difference.

Don't be driving under load at 240 or you may blow a hgasket or worse. Here in Florida, The majority of engine problems initially stem from overheating.

 

running a 160 would not be to low? ive been told that a 180 is as low as i should run one. would running it without one tell me if there is a problem with my old one.

 

Yes 160 is too low, for a number of reasons.

I run 192, but my cooling system has sufficient capacity.

When running an engine too cold, your mileage suffers, you can get condensation in the oil, and your oil also develops acids you don't want and all this translates into premature engine wear. There is much more to it than this, but no need to go into it here.

You need a Clean system of adequate capacity and you will be fine.

You can test the thermostat only by temporarily removing it, or by boiling water on the stove with the thermostat and a thermometer.

How old is the radiator? It's probably not up to full capacity.

 

I have to repectfully disagree on some of your points....the engine will not run "cold"...you're gonna generate heat with or without a stat...the horror story you decribe of the results of not using a stat, IMHO, may occur if you never change the oil and it would take hundreds of thousand of miles to occur, if it occurs....and....IMHO...engine wear occurs more on a hot engine then it ever will on a cool engine...IMHO
And lastly, if a manufacturer thought a 160 would be harmful, or that they wouldn't sell, there wouldn't be any for sale...but you can buy one anywheres....I think we're splitting hairs here... a 20 degree change in temp is a drop in a large bucket, IMHO
Quick and easy? Get a quality stat and put it in and if the car is normal after that, this discussion would be moot, if it continues to run 220-240, pull the stat "for a week" and run it...if it diesn't cool down without a stat, you have other problems...

 

take a 12.5% pay cut and let us know if that is a drop in the bucket. someone (I think it was Norval) posted an article on a study that was done on eng wear and the diff between using a 160 and 180 and it was pretty significant, I'll see if I can dig up the article

Not telling you want stat to run, that is your choice

 

AGAIN...
I am not recommending he run no stat or a 160...I am saying he WILL pop a motor if he continues to run at 240...and to leave the stat out for a SHORT period shouldn't cause any damage...do you agree with that in any fashion or form??
And as far as running without a stat, I am speaking from experience...back in the 60's and 70's, only because I couldn't afford a new stat, I've run many cars without a stat with no noticable damage to the engines, as long as oil changes were regular....that's all...

 

Agree it would not hurt it but I would put a new stat in so you would not have to pull the housing again, if the problem persists then look elsewhere and you will have a new stat in place

 

Yup...somebody did mention that option

 

no reason at all to pull a t-stat and run a car without one as suggested as long as the t-stat it slef is functioning properly. I'd never run my cars without one although I'm well aware people do without apparent harm.

your '78 should have a 195* t-stat in it. The later models were designed to run at a somewhat higher temp for emmision purposes and while you could install a 180* t-stat i'd stay with a 195* model.

Remember, no matter what temp level t-stat you install it will make NO difference on what the engine temps will climp to, the t-stats only dictate what the minimum operating temp is.

so far this thread seems to have concentrated on the t-stat mostly on discussion of your tstat and I duobt very much that has anything to do with your running hot issue. Usually a t-stat either functions or not and if it wasn't functioning most fail in the "closed" position except for a few models and if that were the case you wouldn't be overheating, you WOULD be overheated entirely and puking coolant out, not just running warm.


Start at the basics to find your problem:

1. first, make sure you ACTUALLY have a problem. use an IR temp gun to shoot the upper radiator hose once the car is up to operating temps and check to see if it verifies the temps shown on the guage. More than one person has chased an "overheating problem" when there wasn't one simply because of an incorrect gauge or temp sending unit........ myself included!

2. check your timing!! running too retarded or too advanced will definitely cause the motor to run hotter than normal.
You say your valves are rattling....... are you sure it's the valves and not detonation you are hearing? If it's detonation you are running your timing too advanced. Running the timing too retarding usually causes more problems with running hot than too advanced but too advanced timing does also cause a motor to run hotter.

3. check to make sure all the proper radiator and core support seals are in place - they are very important to the cooling! Make sure your air dam under the nose is in place - again, also very important for proper airflow to the radiator.

4. the fan clutch is easy to check. first, do your temps climb when sitting at lights and drop on hwy driving or do they go up and stay up? if they go up and stay up it's propbably not the fan clutch. To check operation of the fan clutch get the motor up to operating temp ad than turn off the motor. if the fan clutch is working properly the fanblades should stop turn within 1-3 revolutions. If it continues to freespin for a while after shutting the motor down the fan clutch needs to be replaced.

5. check your carb air/fuel mixture. If you are running too lean it can also cause you to run at somewhat higher temps.

6. also check your radiator cap

 

it only hits 240 when im running at speeds 65-70 it seems to run a little cooler when i drop speed down to about 35-45. im running what i would assume is the original radiator. and as i mentioned i am a first time owner of a vette and i didnt know there was supposed to be a air dam under the nose . mine does not have one. and now that i know that i am checking in to buying one.