Head gasket or something else (pushing coolant out)

[2004l67]

Just picked up a new to me L67 car that I'm having some issues with.

After a little drive the system pukes into the overflow jug but never draws it back into the rad once it cools. A sniff of the overflow jug or filler neck has a faint odor of exhaust gas too.

No coolant in the oil, no oil in the coolant, no white smoke or other telltale signs.

Could the supercharger be pressurizing the cooling system via a bad gasket and even pumping EGR gasses in? Or am I most likely looking at a head problem?

[Scottydoggs]

you can try a new radiator cap. they do fail over time. bad t stat can also cause this.

if it keeps over flowing the tank with a new t stat and rad cap it sounds like a head gasket, i got the same issue, blue devil head gasket repair does work. my engines got like 230,000 on it, so i just picked up a used engine.

one way to tell if the gasket is bad is this test. if you dont have a cool funnel like in the vid you will see the same thing in the rad. if you see that rush of bubbles after letting off the gas, its a head gasket for sure.

[2004l67]

Actually it is a new cap, the old one broke when I first checked the fluid when I bought the car.

I do have one of those funnels. I kept hearing air in the heater core so I used it to burp the system last week. I didn't notice any bubbles then, but did notice the fluid level flucuates a lot at the stat opens and closes.

Everyone I talk to says headgaskets are so rare to go on these. I'm thinking about pulling the supercharger belt, burp the system and take it for a spin. Also rent a pressure tester from Autozone.

Another new symptom that just started is a cylinder 5 misfire. Argh.

[Scottydoggs]

take the two hoses to the heater core off the alt bracket, flush it with a garden hose, thats the only way to get the air out of the heater core.

and thats what mine does, 2 cups low every day, but a full overflow bottle. id leave a small puddle under the tank after parking it every time.

i bought a bottle of blue devil used it and dont ya know, my coolant stayed full, and the tank no longer over flowed.

i also had the bubbles in the rad like the vid.

my engines got over 200,000 so i planned on getting a new used engine sooner or later, so i tried the blue devil. its been in there like 2 or 3 years now, still kicking.

[2004l67]

So the radiator pressure test checks out okay. No more than 15-16 PSI hot running at idle. When revving it up it actually drops a bit.

Re-did my test with the funnel bubbling and used the block tester from autozone. No signs of exhaust gas there.

Changed the stat again with a 180* and drilled a tiny vent hole in the edge to help air bleeding. Bled the system down, topped everything off. Going to keep an eye on it and see what gives.

One thing is for certain, there is a ton of old deathcool gunk floating around in the system. Once it stays above freezing I'm going to start flushing it out.

[Scottydoggs]

just keep checking the coolant level every other day in the rad to make sure its not getting low. if its getting low, its going somewhere.

[wowitsfast]

ill second the blue devil i used it on my 3400 (notorious for head gaskets) put alil cooler fail open tstat and has been good for a few months

[99GT2dr]

Make sure you pull the lower rad hose when flushing to get all the chunky dex out, it sure ain't coming out that little drain on the lower drivers side of the rad. After a solid flushing with the garden hose and having lots of orangey stuff come out, I ran Prestone flush for a couple weeks and had a lot more of it come out on the next flush. When the weather gets better, I plan to add distilled vinegar and run that for a week or so to get more out.

[2004l67]

I did a few flushes yesterday and got a lot of crap out. Ran it with distilled water for 30 minutes and it's nasty again. Gonna just keep on it.

With the clean water, engine hot and running you can see the bubbles in the overflow much more obviously. And they definitely smell like exhaust. Just can't figure out why it doesn't fit the rest of the typical head gasket symptoms. (No overheating, no obvious coolant loss, no undue pressure on the cooling system.) Last time I pressure tested a bad headgasket car, it almost pegged the pressure gauge on the tester. This looks normal.

[Scottydoggs]

its a one way leak, it only pushes exhaust gas into the engine, only loss of coolant is out the rad cap.

i got the same issue. while its flushed to water, once its clean water add blue devil all your problems will be gone. then only remove the coolant from the rad, and add one gallon of straight new coolant to it after you follow the directions on the bottle. you want as much of the treated water to stay in there. so dont drain the block. i used a thin tube in the rad and siphoned it out.

then down the road you can do head gaskets or blow it off like most will cause its still not loosing coolant.