Head gasket/exhaust gases leak

[Park]

This might help someone...or not.

 

This is a JDM now with around 100k on it. There is a leaking head gasket, and I'm assuming that it is one of the graphite gaskets (more prone to failure?). It was overheating a bit, with the temperature cycling up and down.

 

It was suggested that I remove the thermostat, so it wouldn't interfere with the water flow. That made a bit of sense since that is where I've read that a "bubble" forms, and that might help it flow to the radiator. I found that during the winter, instead of the normal 1.5mi to hit operating temperature, it would take at least 5. With the heater on, the temperature would actually get lower on a cold day.

 

I still had the cycling problem on long drives, usually after 50 miles or so. Since I have a JDM engine for the usual reason, I'm always afraid of overheating. I thought about the symptoms, and what I could do.

 

I bought a new venting Stant radiator cap. I put it on, but did not turn it until it locked, but stopped a little before that, but it was certainly snug. I lifted the lever, and moved it to the side, figuring that might reduce the pressure a little, and allow gases to flow to the puke tank.

 

Since I did that, I haven't had it move past the normal operating temp (9o'clock, or just below). I still have to add fluid, but I already had to do that, just not as often now.

 

I think there are several benefits to this temporary symptom solution.

 

Heat stays lower. The air pressure doesn't build up. I think that pressure has only 3 places to go. It isn't going to increase the size of the aluminum block, so that is out. It might change from exhaust gases leaking into the radiator, to pushing water into the oil- which I think would be much worse.

 

But the primary place it can go is into making the upper radiator hose into a balloon (and at the same time maybe preventing water from flowing well- until pressure built up enough to force past the cap gasket into the puke tank (source of cycling?), or cracking the plastic parts on the radiator.

 

It doesn't solve the base problem, but I've also had less air in the radiator when I fill it, and the temperature stays low.

 

That's my theory, and I think it will buy me some time until I can fix the gasket issue.

[spooln30]

Usually if headgaskets are bad between a cylinder and coolant jacket then the cooling system will pressurize well beyond the 14-15psi and push coolant into the overflow bottle and once that fills on the ground. Do you get any white smoke ot of the tail pipe? Subaru engines seem to like the oem MLS headgaskets. I hate the composite type head gaskets and if a MLS gasket is available I only use them.