Hi, I have a 99 Forsester with exhaust gas bubbling out cooling system into the overflow tank. Combustion chamber head gasket leak.
I tried the non glass type head gasket stop leak and it did not work at all. I used Perma-Tech, Dura-Seal and no improvement whatsoever, this stuff was supposed to be formulated just for 4 Cylinder Subaru’s and it cost $150, which is a huge rip-off because it does not work. It’s money back guaranteed but I had to contest it with my credit card company to get my money back. So Subie owners beware. Then I tried some Bars Leaks stop leak Head Gasket Fix #1111 and it only worked for a day because I drained the system after using it. Then I tried it again leaving it in and it seems to be working, not 100% but it’s only been a week now and it does seem to improve the more you drive the car. I strongly recomend removing the thermostat when using these products and leave your heater valve open all the time once you put it in and leave it in. Gut an old thermostat and just use the disc shell so you can put the gasket back in, the gutted disc will hold the gasket in place. My 4 cylinder 99 Forester does not overheat without the thermostat, the water flowing thru the radiator too fast theory does not apply with this engine. Anyways, it appears any product you have to drain from the system after use will not hold, you need a quality product that is designed to leave in and that appears to be what’s working on my Forester. Unfortunately, this means your water pump has to endure the metal flakes in these products so the jury is still out on how long the water pump will last. As far as the heater core getting plugged up, as long as you flush your system well and already have good flow thru your heater core you should be fine because these products are designed to only harden in spots where there is high temperature, the engine block not the heater core but I recommend you drive around with the heat valve open all the time just to keep an open flow thru it. Follow the instructions and I recomend placing a small rag by the throttle to keep the engine idling at about 1500 RPMs for at least 20 minutes after you put the stop leak in. Let it cool then top it off and drive carefully, try to stay under 3000 RPMs for at least a week if you have a combustion chamber leak like mine. Make sure you try to get it up to normal operating temp when you drive it, which is a little tricky when just driving on the freeway without a thermostat, stop lights and city driving should let it get up to temp. This way the circulating stop leak keeps coming in contact with the head leak over and over again hardening more and more at the leak repeatedly. I will post again and let everyone know if it’s still holding and the status of my water pump and heater core. Anyone else have any luck with combustion chamber head gasket leaks using stop leak products ?