I have a 95 corvette LT1. I have been trying to fix all the things that were causing my car to get hot. How it has come to this, I replaced the water pump, and the thermostat. The car acts like its a fan problem. When I turn the AC on, it runs cool enough. When the AC is off, the car starts to get hot again. I have seen the main fans turn on, but im not sure if they are turning on at the right time. Please give me an idea of how and what I need to check out to solve the problem (assuming the fans are ok). Thanks a lot,

Burt

 

Are you sure its overheating or just running hot because of summer?

With the AC off only the one fan runs until it reaches 221F then it kicks on. If the AC is on it may allow it to get up to 220 in stop and go traffic for example, but you should see it cycle up and down especially once you get airflow going again. The important thing is if it is cycling, meaning it reaches a certain temperature then starts to fall off.

Make sure the front intake is clear of debris on the front radiator. Also look at the radiator housing from the passenger side there is an opening there that lets you view the front side of the second radiator. Make sure debris is not in there too. I had to fabricate a piece of PVC 3/4 with an angle cut on it and taped it to the vacuum cleaner hose and VERY CAREFULLY suck all that junk off. FYI the opening just allows the 3/4" PVC tube to slip thru there.

Have the coolant system flushed, and bleed the two bleed screws. Always take precaution to keep coolant from getting to the opti.

 

i believe my 89 has an auxilliry fan in front of the rad that turns on at higher temps and when the AC is on..is it working??? maybe it is kicking on when the AC is on but not when the the temp of the motor indivates ut should...just a thought

 

You didn't say how hot it's running... I don't mean to be insulting - but these cars naturally run hot!

When I was installing a new air intake system - I accidentally dropped a fastener in between the two radiators... well I needed that fastener so I took a little bit of time (it was actually pretty easy) and opened up the space between the radiators... I couldn't believe my eyes!!! The space was half way filled to the top with leaves and debris - including a plastic bag and a burger king bag too. I simply got out the wet/dry vacuum cleaner and sucked it all out. I was really suprised as the radiator was replaced 2 years earlier.

You can also try running a 160 degree thermostat and they make auxiliary switches for fans - you can make them manual or set them to come on early.

If the water pump wasn't dripping or making noise - it probably didn't need replacing, did you get a 160 degree stat? Did you boil it on the stove in your kitchen to make sure it works before installing? I actually found that I had bought a new stat and when I boiled it, it didn't open - so I had to return it for another one.

Some people drill a hole or two in their thermostat. When is the last time you checked or changed the radiator fluid? While I'm not a mechanic & not very familiar with your year car... I've heard where people have their wires crossed and the fan blows in the wrong direction.... (just a thought)

I hope you figure it out and let us know what it was...

 

i was asssuming he hgad allready done that...but its a great point mine ran an easy 20 degrees cooler afetr i cleaned it out..half full of leaves and everything else

 

Here's a picture of what we are talking about when refering to the area between the two radiators. This is looking from the passenger side through the housing opening.

 

The idea of making an adapter out of 3/4" pvc to vacuum out the front of the radiator is a good one.

 

I know LOL!, more like desperate thinking, my stinkin' vacuum cleaner hose is way too big to fit in the opening. I didn't want to remove all these housing and connectors and drain it down some. So I cut a fairly shallow angle (as much as those PVC cutters would allow) so that it made better flat contact because of the angle it goes in there. Then some good ole duct tape to the vacuum hose. I also tapered the edges so they wouldn't be sharp.

I tell ya though I was really careful and real gentle with it so as to not damage the fins on the radiator.



[Modified by 93JetJocky, 11:04 PM 6/25/2004]

 

I just got my vette last week and a couple days ago noticed this same problem. Only runs cool when the AC is on.
As far as how hot it gets, it got up to about 'one temp needle's width' from being in the red-zone on the gauge. I forgot i could flip through the digital gauges to get a number in degrees, but i'm guessing that just a hair above the red zone on the gauge is too hot. As soon as i turned on the AC, the gauge dropped to around 200-ish...

So, where is the switch that controls the fans when the AC is NOT on?

-Mike K.

 

The two relays are located on the driver's side of the radiator housing. Forward is primary and aft is secondary fan relays. There are 4 switch connections for the AC along the passenger side near the blower fan housing.

The ECM turns the primary fan on any time: you have a DCT 14, 15, 52, 62, ECT (coolant temp) is above 108C (226F), EOT (oil temp) is above 108C (228F), or AC high pressure signal from AC pressure fan switch.

It turns on the secondary based on: DCT 14, 15, 52, 62, ECT above 112C (234F), EOT 113C (235F), or AC high pressure signal from aC pressure fan switch.

Your digital info is probably more accurate then the analog gauge. Easier to determine the exact temp too no guessing. (On my analog, its a half needle width past half way mark is around 200F.) Not completely sure of the scale on the analog gauge, but if half way is 200, and max is 260, it must look awfully close to redline when its at 235F.

If you have electronic air set the temp to 69F if you don't need much AC, it will at least cause both fans to kick on. LOL I run mine even when the top is out.

 

I'm sure someone can help me out with this one as I don't have my book with the Temp numbers everything should turn on at but when I had problems with my 95 getting hot I did the operation check by letting it idle until it warmed up watching the temp for the first fan to turn on and then the second and cycling the ac to make sure the fans were cutting on with it turned on which it sounds as if yours are. In the long run I found out mineb just needed to be burped and then the problems went away. Good luck

 

The cars a designed to run hot. Heats the cat for better emissons numbers.
There are ways around it. My 85 had a after market fan and a 160 thermo.
The after market fan came on earlier than a stock fan and the car never overheated.

My 86 was stock with the aux fan in front and it always got hot in stop and go.
220+.

My 93 has the thermo master chip and 160 thermo. It runs the coolest of all.
Fans come on at 180. Passed emissions no problem. The chip does effect the cars factory programming. Other than fan control it is the same settings as per the factory. The chip changes the program after 2000+ rpm.

My Z-28 ran hot so I hooked up a bypass switch to operate the fan remotely.
It never got hot again. At 190 I switched on the fan and off at 180. Never used it except a parade which is most of time here. Adding a remote does not affect the factory operations. The fans will still come as before (automatically). Mid America sells the kit for a remote switch. Its less than $25.00.


Cleaning the radiator:
I work in car shop so I used the air compressor with a blower to go thru the side of the radiator to blow out all the junk. Works very well.
The LT-1 going thru Las Wages Nev stuck in a crawl for 1 hour got to 220 in 100+ weather.

Depending on where you live a 160 or 180 thermo can help but turning the fans on early is the key to being cool. That and a clean radiator.

Corvettes are no differnet than anyother car.