compajd

Here is my story. I have a 1994 LT1. And it has been overheating.
COOLANT TEMP: ANALOG: 260 IN THE RED
DIGITAL: DOESN'T GO OVER 228

Coolant was boiling into the surge tank so I did the following:

1) I flushed and replaced the coolant.
2) Replaced the T-Stat
3) Replace the Radiator Cap

I tried to burp the system but I when I ran the car until the digital hit 180F the coolant level doen't go down much. Could this mean the T-Stat is stuck.

Still boiling over. Need your help guys. The next step is replacing the radiator. :eek:

Carolina C4 Racer

I had the exact same problem once caused by overfilling the system.
Suck out the overflow tank & drive it agin to see what happens.
I hope this helps, at least it's free.

joeveto

Don't go replacing items, without actually knowing they are bad.

First off, make sure the system is bled. That means putting the front end up in the air so the radiator cap is the highest part of the cooling system. Then, start the car and let it idle for ten minutes. Every minute or so, increase the idle to 2000. Then, let it go back down. Give it time.

Make sure the path to your radiator is clean.

Also, if you have any doubts, test your thermostat. I never install one without making sure its good. I've had brand new ones that were worthless, and 50K mile thermostats that were fine. Take a medium sized saucepan and a yeast thermometer (or suitable substitute). Then, heat the water and watch at what temperature the thermostat opens.

Good luck with it. I really don't think your radiator is bad.

Cherry6speed

Yeah, I did the same thing. Try opening the radiator cap and starting the engine cold. Then, turn on the heater and wait a couple of seconds. Rev the engine and look in the radiator cap hole to see if you are getting flow if so, cap the radiator and squeeze the top hose while you are bleeding the passenger side bleed valve. Coolant flows out-close valve and bleed the other side (intake bleed) . Repeat the procedure until you no-longer have air in the system. Be careful to monitor the temps. When you have air in the system, it only takes two minutes to really heat up. Good news is, when you burp the air out , it only takes two minutes to cool the temps down. It worked for me :)

compajd

Where exactly are the bleed valves on a 94 LT1. There isn't anything in the Chilton Manual that helps me locate them. And also when testing the T-Stat in boiling water do i just drop it in the pot or suspend it in the water with a hanger. Big thanks guys keep the great advice coming! :D

Cherry6speed

Thats good news, this is probably your problem. Follow the top radiator hose to the thermostat housing and look to the side of the housing. there is a brass flat blade screw. That is bleed number one. Second one is hidden under the throttle body by the cable under the right side (facing the motor) It also, has a brass screw. That is bleed number 2. Try bleeding the air out while you squeeze the top hose until fluid comes out, then close valve and repeat. Follow the guide earlier and you should have that puppy cooling shortly. :steering:

Pete K

If all the above advise fails, and I hope it doesn't, borrow a pressure tester to see if a head gasket has blown. I hope this isnt the case but a pressure tester is a great tool to have access to.

smar

I had the same problem years ago. I tried the above mentioned remedies without any positive results, later I found that the front of the rad was covered with a mat of poplar fluff that passed thru A/C condeser therefore it was nor visible from the front. I removed air filter and top shroud and used pressure washer to clean it.
:thumbs:

silver84

Take the t-stat out, run your 'vette a few minutes,
and tell the forum what happens. :auto:

crheinish

I had the same problem. Turned out the radiator cap was not holding pressure. New cap fixed the problem. :cheers:

compajd

I will try every thing this weekend and I will keep you guys posted on what the problem is if i fix it. Thanks for all the input guys keep it coming. I love this forum!!!

compajd

Here is what I had a chance to do over the weekend.

1. I removed the radiator and pressure washed it. The damn thing was filthy
it had plastic bags stuck to it along with leaves, hairs, feathers rocks
and dirt.
I pressure washed it for about an hour. It removed most of the material but
there are some pebbles in there that wouldn't budge.

2. Tested the thermostat and it was fine. (IT OPENS)

3. Tested the fan and it turned on when the digital coolant hit 227.

4. Burped the system.

5. Checked the water pump.

Seems ok but when i ran it for about 30 minutes the analog went all the way to 260. (But it didn't boil into the surge tank). Raising the RPM to 2000 occasionally. Digital was under 220.

So I am beggining to think this is normal temp. for the analog. What do you guys think.

John Row

Digital sensor and analog sensor are two different devices. Digital is on the front of the pump housing (easy to break off when you work on the housing). Seems to me the analog is on the side of the block somewhere. Maybe someone will chime in.

195-230 is normal temps for an LT1, I no longer get excited when it hits 250 under hard driving conditions.

crheinish

Sounds like you fixed it, congrats. The analog gauge is for reference only and is not very accurate. The digital gauge however is very accurate. Your analog sending unit may be on its way out. Easy fix it is located in the cylinder head.