GUYS C 4

I have a 94 LT1 that has a persistent smell of antifreeze when the car reaches operating temperature. I have flushed the cooling system and replaced the anti freeze twice with Peak Lifetime Gold,replaced the cap, and pressure tested the system to 20 psi many times and it holds pressure for over two hours without losing a pound. I never have to add, it stays right at the full mark. This car has only 27,000 miles and all the hoses are still like new. The factory service manual says to add 6 cooling system pellets. I really don`t want to put that crap in a perfectly clean system but the smell is really annoying. Any one else ever experience this problem ?

73n95

My 95 does a similar thing. The smell isn't continuous, just an occasional whiff but it makes me nauseous. I've driven 3000 miles and may have lost a half cup or so, but who can tell. Can't find a leak. Leaky heating core seems to be a possibility but can't find any leakage. I will be interested in seeing the responses.

zr1fred

Two choices. You're hypersensitive, or the heater core. They usually seep before they leak, and they are the only place there is coolant in the passenger compartment (unless you spilled a bottle).

c4cruiser

Even though there isn't any loss of coolant, it could be a very small or intermittent leak from the heater core. Is there any indication of moisture in the passenger side footwell? Maybe up towards the top of the carpeting? Is the smell stronger when using the heater at temps like 70-75 degrees? With the temp turned down and the heater set to off, do you still smell coolant?

While the FSM does recommend the use of the "Cooling System Pellets", GM stopped that some years ago. Just use regular ethylene glycol (green) coolant in a 50% mix with distilled water.

DGXR

The exact same thing happens in my 1995. Never lose any coolant and the coolant smell does not happen every drive, and the smell is not constant either. When it happens, the digital temp gauge is around 130-150*F, I get a good whiff of coolant inside the cabin and then the smell goes away pretty quickly. No dampness around the passenger footwell and I have checked it thoroughly several times. Only 65k miles on the car and all evidence indicates it has been very well maintained. Did a coolant flush shortly after purchase, it was still very green with no sign of scale or sediment. All the HVAC systems work fine.

So I have no idea what is going on but I am interested in this thread.

sluggballz

Cycle your cabin temp to open and close the blend door. If it's the Heater core leaking very slightly, you'll notice it when the door is open for heat and it goes away when you close the door for cooler air. I had a very very small leak in the core and that was the one way I determined it to be the core because there wasn't enough to wet the passenger compartment.

gdl2165

My vote's on the heater core. I bought my 96 a little over three years ago and had the same issue from the beginning. About 1.5 years ago it got worse and I actually started experiencing a bit of misting on the inside of the windshield. Replaced the heater core at that time and found it was just barely seeping, not enough to cause any moisture in the floorboard. Been fine ever since.

john6277

Same issue in my 95 coupe for the past year after replacing coolant due to age and mileage. Not a big problem, but I would sometimes faintly pick up the familiar antifreeze smell. I finally ordered the pellets from Amazon and used 3 of the 5 in the pack. Big improvement and I can live with it now. Maybe a new core if it gets really bad at some point in the future.

scrappy76

You would be amazed how much smell comes from the smallest drop of coolant, especially when its warmed up. I will bet your heater core has just the smallest leak and it will take forever for it to show in the amount of a loss when Your car is 22 years old and only has 27,000 miles on it.

I had a jeep liberty that had the smell and I drove it all the time. It took a year later for it to start showing a loss and that was because the heater core leak started getting worse, and if you were to continue to drive yours more and more, sooner or later you would start seeing a loss.

antfarmer2

Put some uv dye in it you will find it.

scuba717

A cold pressure test won't pick up the problem You probably have a very small leak that only opens up at temperature. If it's the heater core you should be getting a film on the inside of the windshield when the defrost is on. You should also get a much stronger smell.

73n95

Until I can work up the courage to tackle the core I will install a heater bypass circuit under the hood. If it gets cold I just open it up. Sort of a half-assed fix-it but I really don't want to go under the dash.

GUYS C 4

Sorry I could not get back to all of you sooner. Thank you all for your response. This is why I love the Corvette community. I failed to mention in my original post that The smell is not in my interior. it smells the most at the top right side of the radiator by the air vent hose that goes to the pressure tank. I am curious about the GM sealant pellets. I thought I read somewhere that these were installed in the factory. Has anyone tried them, and if so do they contaminate the system with a sludge like the store bought stuff? I know the factory service manual recommends them for the water pump seal weeping.

antfarmer2

Might take a closer look at the cap and it's mating surface. I you got a replacement cap that could be it. Get a real cap others have made the same mistake. Check your overflow hose to they get old and cracked and a easy fix

zr1fred

Yeah, that might have helped.

RUU

Original rad? It's not a matter of "if" the plastic side tanks fail but "when".

belairbrian

I did mine (92 coupe) . It isn't fun, but not that bad. just time consuming. The FSM procedure pretty much walks you through it.

A working heater core can help get an overheating car to a safe stopping location.

GUYS C 4

The cap is new and pressure tested, opens at 15psi. the tank surface is clean and smooth and the over flow hose and tube assembly is like new. pressure test and leak test with bubble solution was negative. no sign of leak or pressure loss.

steve1657

antfarmer2

Ok now where did you get the cap? No sign of leak? Then what is that smell? Did you run the gas check for a head gasket?