prog-guru

I found my 94 with no coolant yesterday, and a big puddle near the front right wheel. Hard to tell where it started, it was raining. There was coolant in the translucent reservoir in the front of the car, and none in the black one (the one at the top, where the radiator cap is). Low coolant light came on.

I changed the cap and filled with 50% green coolant, and noticed the part that the cap mounts on is loose (the 'filler neck'). I can rotate it in either direction, and I see some dried coolant near there, especially under the hose that comes out. It it supposed to be loose?

I sure hope my water pump + optispark are OK, there was coolant all over the belt, which left a thin coat of coolant on everything in it's path. Car runs fine though, temps normal (coolant goes up to 230, fan kicks on, drops, etc). I ran it last night for maybe 30 minutes, drove it maybe 3 miles, did not see any more leaks.

And what is the stock thermostat in a 94? I assumed 194 (like my 85), but watching it run it looks like I may have a 185, coolant temp sat there for a while while idling.

STL94LT1

Stock thermostat in a 94 is 180*.

tkrussell

Sounds like a leak somewhere. Fill the engine if it needs coolant, put the cap back on, and run the engine up to normal temp. Now look around at all the hoses, fittings, etc around the right front tire. There are a bunch going to and from the coolant reservoir and heater core (under the reservoir. Look for a leak or drip.

I have noticed that the filler neck of the coolant reservoir is not soldered in, so vigorous twisting will move it back and forth. It should not be loose enough to turn easily, however. If it is, that may be the source of your leak. Poor design!!

The LT-1/4 have reverse flow cooling, so the thermostat rating will not be the same as the temp you measure. On my 95 with a 160 Stat, the temp runs 173 minimum. So a 180 stat will probably indicate 190-195 on the guage minimum.

prog-guru

I found a leak, the cover on the water pump was dripping right onto the belt. I guess I'm lucky, at least I found it. Waiting for the RTV to dry now.

Thanks for the info on the filler neck, it is not super loose, but I did see it move a little when I was messing with the cap.

John Row

Hopefully you didn't take out the opti. If it runs lousy at first let it dry out throughly (sometimes takes 2-3 days) then try it again.

I'd start budgeting for an opti. If this didn't take it out outright, then at least it started the process. OPTI + ANTIFREEZE = nothing good.

There are a lot of LT1 owners on the CF that are way more familiar with their opti than they ever wanted to be. We can get you through replacing it when the time comes (and it will).

prog-guru

So far so good, no leak at the pump right now, I'll check it in a few hours when it cools more.

I think I am going to have to do something about the filler neck, it is leaking a little. Anybody else seen this?

don hall

The expansion tank is made of plastic, not metal, and the neck should NOT rotate. I'm not talking about the overflow bottle in the front well. I don't understand how you removed the cap with a loose neck. Definitely fix the neck from leaking, or replace the tank.

PTz-92-LT1

Had the same thing happen to me.:yesnod: Just buy another reservoir tank and replace it. I attempted the back yard engineering with epoxy...what a mess and it didn't hold.

New Coolant Surge Tank #244463 Corvette Central $47.05

don hall

Right from PTz-92-LT1's mouth: "Don't mess with the tank.......BUY NEW!!!!!!!

ittlfly

What he said!

riksvet

Ran into the same situation on my 95. Replaced the tank still had it. Did not tighten the hose all of the way. Leak still there, had the tank too full at cold so when it heated up it got close to the vent on the cap when I was bouncing the car around corners and it cam out the top and sits on the shield there and drips when the car stops. This is the white plastic tank under the headlamp not the expansion tank near the windshield correct.

Rick Springer

don hall

****** riksvet ******, you have probably corrected your coolant problems, but just in case: fill the plastic expansion tank (mounted right side, high, near fire wall) completely. Fill the overflow bottle (white plastic bottle, right front well) about 1/3 full (to the FULL COLD MARK). Make sure all hoses/tubing are secure at both ends to ensure expanded coolant syphons back to the expansion tank from the overflow bottle as the engine cools.

prog-guru

I am talking about the black tank near the windshield, I think it is the 'surge tank,' $47. It's not really too bad, but it looks like I am going to replace it, hope it's not too complicated (sensors, etc).

don hall

Good move. Just take care removing the hoses. No sensors. Drain off a gallon, or so, of coolant to eliminate spillage when removing the hoses.

darkredlt1

There is a y hose that comes from the back of the engine and surge tank and goes to the radiator. It has rubber connections and metal lines. I was changing my plugs and moved it around some and it started leaking. I expect that the rubber dries out and gets brittle. Anyway, be easy with yours when you change the surge tank. Maybe some dielectric grease would revitalize the rubber. My '94 is giving me good service. 130,000 + and only wear and tear problems in the 5 years that I have had her. The radiator probably needs to be taken out and the grass and such vacumned and washed out. There is a tech tip about this.

prog-guru

Just got the surge tank done, went pretty well. I had to redo the seal on the pump 2 more times since my last post unfortunately, hopefully it will hold this time.

RideWithGreg

The low coolant light came on. The lower overflow tank was full (not just to the line, but overflowing) and the upper surge/expansion tank was empty. The radiator cap is several years old, so I figured was not holding pressure and replaced it. Testing it, I found that when the engine got hot, coolant started spewing out from around the (new) radiator cap on the upper tank. I finally noticed that the filler next had several cracks in it. Changing the tank took less than half an hour; flushing and filling the coolant was the hard part. After replacing the tank everything is working fine.

But I don't see how the cracks in the filler neck could have produced my original symptoms (overflowing lower tank). My best guess is that the cap was bad and removing and installing it several times caused the filler neck to give way. There were several vertical cracks in the neck and at least one circular one following the curve of the fill hole.

FYI: The tanks are now $75. My local brick and mortar auto parts stores do not sell it, the local Chevy could get it in a day, so that left the Internet. There is no standard name for this tank, so it is difficult to find, but is widely available on the internet. I live within driving distance of Eckler's showroom and they not only had it in stock, but price-matched the cheapest price I could find.