I just got a 94 Corvette as a weekend driver. I notice at low speeds or idling my engine starts to run hot. Is this normal? If not, how can I fix it or diagnose it correctly on the first try-I don't wana spend several hundred dollars if I don't have to. I have never let it get over about 220 by turning the engine off-so it may continue to get hotter if I keep letting it idle longer. When I am driving on the hwy, it runs between 180 and 195.

The digital and analog gauges also do not seem to be exactly in sync. I know the analog isn't linear-I am going by the chart in the owners manual. Sometimes the digital gauge seems to run a little lower than the analog. And sometimes its the other way around.

Bottom line, I have never had a car of any kind where the engine starts running hot in slow speeds-my temp gauges on all the other cars I own get to the correct temp and stay exactly there. I want mine to run at 200 or less at all times if possible.

Also, please reply with layman terms-I don't know crap about LT1s (I am new to this) and what all the acronyms, where stuff is located, etc stand for. Like I don't even know where the thermostat is on this car. Dummy it down. Thanks.

 

Is the two cooling fans in front of the radiator coming on at idle?

 

Quoted from Hanes manual:Most models use two cooling fans,a primary and secondary. Durning normal operation the ECM will command the primary fan to come on when the coolant reaches 226F. When the a/c is on or the ECM diagnostic coolant code occurs the secondary comes on. The ECM will command the secondary fan when the primary fan is running and the A/C is on and the car is at speeds below 55mph, if the engine temp. is over 235-degrees-F or if a cooling system code occurrs.

 

220 is nothing on these cars. They were designed to run warmer than what we would normally think of as too warm. Your OK unless the temp goes above 250 or so.

That said, here are a few things that you can check and do.

1. turn on the AC this forces the second fan to come on.

2. Some guys put a manual switch to turn on the second fan (so they can control when it comes on.

3. Some people are convinced that putting in a lower degree thermostat (160*) as well as the manual fan switch is the key.

4. If you don't know this just know that these cars are "bottom breathers" they suck air in through the lower part of the front end and they act like vaccuum cleaners suck up everything on the road. This junk collects between the AC condonsor and the radiator limiting (the already low) flow of air through the radiator. You can check this by using a flashlight and looking in the little gap area in the shroud on the passenger side of the engine compartment. To clean it out, there are several schools of thought. What I did was remove the radiator and do a thorough cleaning. While I was at it I changed out the upper and lower radiator hoses, radiator cap, and coolant.

After doing the cleaning, mine dropped a few degrees, but when it is hot and I am in stop and go traffic the temps will still climb to 230* (which used to freak me out), but it is not uncommon for the LT1.

 

congralations on a great corvette cstewTAMU the 94 is a great corvette.
Tom& Yankeecorvette are giving you good info. The hot running is for hp and emissions. Let it idle and watch the fans 220 is to low to know if they are working. They will start about 226 deg and the temps will fall very quickly then stop and the cycle will start again after it reaches 226 deg again. On the highway the fans probably never come on because they are not needed. Every thing sounds normal just check that the fans are working and dig out the leafs and dead birds.

 

Which gauge do I go by? The digital and analog gauges are not exactly in sync. Usually, the digital display will show anywhere from 5-20 degrees cooler than the analog gauge, but yesterday (I have only had the gar a couple of days), the analog did momenterily read lower. They do read almost exactly the same when the engine is operating under 200 degrees. It's when it starts to get warmer that they get further and further apart. Today after I posted thistopic the digital read like 223 or so and the analog read about 235.

If I do end up getting a switch to manually turn the fans off and on, is it okay to just run them both at all times? I know everyone has said its okay for these engines to run hot, but I would like to make it where the engine NEVER at any time or operating condition gets over 200, even in heavy traffic for long periods of time.

What kind of ballpark prices are we looking at for:

A manual switch for the fans?
I assume a thermostat is a cheap part...~$20 or so

Where is the thermostat located anyway?

Can I program the fans to kick in much, much earlier? If so, how much $$?

 

cstew
the thermostat on your lt1 is on the top of the water pump with the bottom radiator hose leading to it. There is no need to change it as this will not make your vette run cooler.

I have read you can reprogram the ecm to make the fans come on sooner and with this you change your thermostat and the chip in the ecm. probably costly.

cheapest would be a toggle switch that you would turn on Win you felt it necessary.
find a good ground under the dash run a wire to a toggle switch run the other side of the switch to the relays for the fan located in the drivers side lower headlight area. I think it is a green wire somebody correct me if I'm wrong. I will look at mine tomorrow. You don't want to run the fans all the time they take a lot of juice and the life of the fans will be jeopardized. Also as suggested turning on the ac would do the same thing.

If I had to guess on the righttemp I would go with the digital read out it works from the temp sending unit mounted on the front of the water pump. If this sending unit was bad I think you would have other issues with the car.Theanalog sending unit is locatedunder 7&8 spark plugs.

cstew in my opinion I think your jumping the gun the cars design is to run higher temps. then most are comfortable with.

There is a ton of info on this sight on a c4 running hot do a search and read up on this subject. I will check on that wire color tomorrow.

Ric W.


cstew
at the left(drivers) side of the radiator you will find 2 relays for the fan they are attached just forward of the radiator on the shroud. the forward relay has a green wire with a white stripe on it. that is the wire you want to run a ground through a toggle switch to. I am looking at a 92 but yours should be the same. hope this helps you

 

I agree with Ric, this is the way it was engineered to work.

 

The digital gauge is usually the most accurate and like everyone else has poste - your temps are normal.