I have a '01 SS. I don't drive it in the winter. Towards the end of last driving season I noticed I would have to top off the cooling system every week or so. I checked the radiator a couple times while it sat over the winter, it was full the whole time. Yesterday was the first time I ran it in a few months, before starting it up, I popped the radiator cap, full to the top of the neck. I let it idle for a while after I first started it, revved it a few times and then drove it for maybe 10 minutes. This morning before work I thought I better check the radiator. I popped the cap the level was down about 2-3 inches and took about 6 ounces to top off.

I am really hoping it doesn't have a failing head gasket. I haven't looked real close at anything yet, but I didn't see any coolant on the driveway when I backed out this morning. Are there any common leak points or anything that is susceptible to failure to look at before I start a leakdown test, which I've only done once before. It still has all of the factory spring-type clamps on the radiator hoses, which might be something to look at, but as stated above no visible coolant leaks.

 

Did you check the weep hole on the water pump for staining? Is the overflow losing coolant? One common issue I see with car this age is the system can not draw the coolant back into radiator. As the engine cools it supposed to draw coolant back in from the over flow, sometimes the hose will get so soft it closes and sometime the radiator cap is bad.

Cold system pressure test is you next step. You can borrow the pressure tester for a chain parts store and check out how to videos on Youtube.

 

I have not looked at the weep hole, but I can. I guess it is under the pulley at the bottom center of the pump, is that right? I'm not sure on the overflow, I will have to keep an eye on it. Good point about the cap, it is factory. I don't think the hoses are soft, but I can give them a squeeze tonight.

 

That much coolant usually indicates a bad head gasket. If you're lucky it's being burned. If you're not so lucky, it's in your oil.

 

how does the oil look, if its not milky and your not seeing sweat on the underside of the oil fill cap then i would be hoping and looking for external leak and like gorn says a leaky/failing overflow system will do it.

 

I spent some time looking at the cooling system really good last night. I took a mirror and looked under all of the hose connections, no visible coolant leaking. I looked above the bottom of the water pump as good as I could, didn't see anything. I looked under the oil cap, nice and dry. I don't see any oil residue in the coolant; it's dirty, but didn't see anything resembling chocolate milk or anything else. The oil is clean and at the correct level.

Gorn might be onto something. About an hour or so after I drove it home from work is when I started looking at everything so the motor was a little warm, but not hot. I pulled the overflow plastic dipstick and it was wet well past the full hot mark. I went to the local parts store, bought a 18 lb stant cap with pressure relief, topped the radiator completely off, which it didn't take more than a couple ounces, ran the car for about 20 mins, let it get good and hot to where the electric fan came on, didn't open the cap, shut the hood and went in for the night. This morning before work I popped the radiator cap and the level was about 1/4" below the filler neck. I also looked at and felt the main radiator hoses, none were pinched closed and all were pretty firm.

I'm really hoping the cap was the culprit, I will have to keep an eye on it, but I would have figured if it was the cap it would be like older cars that didn't have overflows to where it "purges" off what it doesn't need and it will stay at that level if there are no leaks, but I would have to add keep adding coolant to mine every so often. Another thing to mention, which I hope is a good sign that it's not burning the coolant, is that when it idles there is just a very small amount of steam coming out of the exhaust pipes which I would think is normal. I had an intake gasket leaking on a Ford V10 when the engine was cold and it steamed so much it looked like it was in a cloud just sitting there idling. When the engine got warm the gasket would swell and seal again, but it was bad when it was cold, so bad my uncle called it a James Bond truck because it looked like it was putting off a smoke screen! lol

 

Keep in mind you only pull the cap off when engine is at room temp. If the motor is still warm you are interrupting the cooling return process. I have had customers that where constantly checking it and adding fluid. There can be nothing wrong with the car but they end up with an over filled reservoir and air pockets in the engine.

Is there a bleeder on your coolant system?

For me I see about 50/50 cap vs soft hose. Its a good idea to replace that hose every 10 years or so or every other battery replacement. I did both Cap and hose as routine maintenance on my last battery change.

 

Yeah I usually only pull the cap when the engine is cold or hasn't been ran for the day, but did it when it was slightly warm because I was inspecting everything. I was thinking about replacing the hoses if the cap didn't fix it and might do it anyway when I service the coolant system because i bet they are the factory hoses. I checked the fluid level again before leaving work for lunch break, the car sat for about 5.5 hours and the fluid was at the bottom of the filler neck again so I'm thinking and hoping the cap did the trick! I really appreciate your help! Believe it or not, my battery is over 7 years old so who knows when the battery before this one was! lol

 

Update: last time I drove the car was Friday after work, Sunday afternoon I took off the radiator cap and it was full to the brim