Cooling problem

[Stallion]

Here's the issue. Around town and at lower speeds/RPMs, the temperature is fine. Around 185, Tstat is opening and all is well. But when I get on the highway with higher speeds and engine revolutions, the temperature drastically increases to 220ish degrees.

The fan is working, the water pump is new, and the tstat is functional (opening, etc.).

What could this be???

Thanks!

1978 L48 4-speed

 

[Vettehead Mikey]

The most common cause is lack of airflow through the radiator core.

Are all the shroud seals in place?

Do you have the stock chin spoiler?

 

[muddywaters]

Stallion, My 88 cooling sys. was doing some strange things, I looked in between the rad. and cond., it looked like a vacum cleaner bag, half full of leaves, lottery ticket, cig. wrappers, I couldn't beleive it the rest of the car was super clean. I had to take out the rad. to clean it properly since the crap powderized and packed the rad...

 

[Vette79]

WOW! That's crazy. Good catch...

 

[jdp6000]

Here's the issue. Around town and at lower speeds/RPMs, the temperature is fine. Around 185, Tstat is opening and all is well. But when I get on the highway with higher speeds and engine revolutions, the temperature drastically increases to 220ish degrees.

The fan is working, the water pump is new, and the tstat is functional (opening, etc.).

What could this be???

Thanks!

1978 L48 4-speed

Do you have a front spoiler? Its not there for looks. It directs the air up to the rad at high speeds.

Jim

 

[minifridge1138]

What size radiator do you have?
I know the 1982 came with a 3 core.
Someone put a 2 core in mine, and I have the exact same problem you described. Fine at low speeds, but at higher RPM's the fluid doesn't stay in the radiator long enough to cool down.
Next month, I'm upgrading to a DeWitt's aluminum radiator, so I should never have to worry about overheating again.

 

[GaryS]

You have some good suggestions to start with.

1. Improper cooling due to obstructions between the a/c condensor and the radiator
2. missing radiator seals
3. improperly opening thermostats including not opening fully.
4. timing off

and the one thing no one has suggested is YOUR RADIATOR!

I fought the cooling system on my 66 for years until I finally admitted that it had to be the radiator. I checked timing, water pump, t'stat, etc etc. An IR gun confirmed that my radiator was not functioning as designed. When I eventually replaced it with a DeWitt's repro Harrison radiator, the difference was like night and day. I could feel the difference between the upper and lower part of the rad. The upper was very warm and the bottom 1/4 was almost ambient. Some day I will cut this old original radiator up just to see what kind of crap is in the bottom. If you remember looking down the neck of your rad, you often saw white precipitate stuck to your discharge tubes. This stuff precipitates out of solution from the old style, green antifreeze.

Btw, I now use Zerex G-05 which is a low silicate antifreeze.

 

[minifridge1138]

DUDE!!! nobody suggested radiator?

Did you read my post? The one right before yours? All I talked about was the radiator.

I'm not mad or anything, but you can't claim to be the first to think it is the radiator. I even mentioned DeWitt's. Although, i did not suggest the Harrison as you did. ( <-- giving credit where credit is due).


Honestly, the radiator is the single solution that will provide the greatest heat reduction.
Also, there is a product called "Water Wetter." It lowered my temp about 10 degrees. But "magic water" is NOT the solution to over heating. It can help, but doesn't solve the fact that you car's cooling system is inadequate.

Good Luck, and I'll let you know how the Dewitt's worked when I order install it in a few weeks.

 

[Vettehead Mikey]

Is anybody going to suggest that maybe it's the radiator?

 

[GaryS]

DUDE!!! nobody suggested radiator?

Did you read my post? The one right before yours? All I talked about was the radiator.

I'm not mad or anything, but you can't claim to be the first to think it is the radiator. I even mentioned DeWitt's. Although, i did not suggest the Harrison as you did. ( <-- giving credit where credit is due).

Hey, don't get your pantyhose in a bind! I wasn't trying to "claim to be the first to think it is the radiator." I missed your post!. Can you ever forgive me for this terrible slight on you?:bash My intent was not to be the first one to suggest anything or to get credit for something like you seem to want to. My intent was to help this owner get his car on the road and run reliably based on my past experience. DUDE!

 

[Curtis]

Now I have a question on engine temperature. I have a brand new factory replacement radiator with 2500 cfm electric fan w/shroud. Engine around 400 hp. Most days cruisin on highway it runs around 190 to 195. If ambient temp is over 100 then it gets to about 200 on the highway. Are these reasonable running temperatures or should it run cooler?

 

[JohnZ]

Now I have a question on engine temperature. I have a brand new factory replacement radiator with 2500 cfm electric fan w/shroud. Engine around 400 hp. Most days cruisin on highway it runs around 190 to 195. If ambient temp is over 100 then it gets to about 200 on the highway. Are these reasonable running temperatures or should it run cooler?

What's the rating of the installed thermostat - 180* or 195*? The fan has no effect whatsoever on highway-speed cooling; in fact, some electric fans reduce highway-speed airflow through the radiator.

 

[Curtis]

It has what they call a balanced thermostat. supposed to be rated 180 One other note, the temp sender is in the head not water jacket by thermostat housing.

 

[zachh]

Buy a lower(cooler) thermostat..... the cheapest way
Take the car to a shop and see if they can do a radiator and cooling system flush. This'll take out any sludge and impurities.

zachh

 

[Curtis]

the block and radiator and everything was new 4000 miles ago, you really think there is an obstruction or crap in there? I thought I was very careful about cleaning and assembly.

 

[zachh]

the block and radiator and everything was new 4000 miles ago, you really think there is an obstruction or crap in there? I thought I was very careful about cleaning and assembly.

Could just be the nature of the beast. Thats a lot of power, alot of compression, and alot of heat. Did you replace all your heater hoses, core, etc. You may not have enough air going in through the radiator for the new engine?
zachh

 

[Curtis]

everything was new, including performance water pump and all hoses. Do you think it should be cooler, it never has been, even before the new stuff. My old Lumina runs about 215 all the time.

 

[minifridge1138]

Hey, don't get your pantyhose in a bind! I wasn't trying to "claim to be the first to think it is the radiator." I missed your post!. Can you ever forgive me for this terrible slight on you?:bash My intent was not to be the first one to suggest anything or to get credit for something like you seem to want to. My intent was to help this owner get his car on the road and run reliably based on my past experience. DUDE!

No problem. I wasn't upset or mad. I just thought that it was funny that you suggested that the radiator was the problem a day after I did, and said that nobody had thought of it. I agree that the #1 goal is to help people get their Corvette running better.

Back to the subject of the thread, Stallion, do you know what size radiator you have in the car? My 2 core is just too small. At high RPM's the fluid flows through the radiator too fast to cool down, so hot fluid flows back into the block. A bigger radiator will keep more fluid in the radiator for more time. I've heard good things about DeWitt's and I am going to install one in a few weeks.

 

[Wayne robson]

thats fine

the block and radiator and everything was new 4000 miles ago, you really think there is an obstruction or crap in there? I thought I was very careful about cleaning and assembly.

hi Curtis those temperatures are ok i would not be concerned that it gets to 200, something i experianced a while back i fitted pertronix electronic ingnition great ,started well ,drove well, made sure i had timeing spot on, but car always ran approx 10 degress hotter than with normal points, here where i live in australia gets very hot, so i refiitted back to normal points and sure enough temp dropped back and this was at 60 70 mph rruising, so i have left it like that keep electronic ingnition in truck as emergency in cash of break down, regards wayne.

 

[Curtis]

thank you Wayne, guess that is good enough for me. I will get out of this thread now. just put up some gallery pics. http://www.corvetteactioncenter.com/gallery/