M20 headgasket question

[Rustyduktape]

im looking at an e30 right now, guy says it has an engine problem. he needs to use a quart of antifreeze every 50-75 miles, it has no visible coolant leaks, oil is clean, oil cap area is sludge free, compression on all 6 cylinders is at 175psi, and he says his engine misses significantly at high rpms, but not consistently. im thinking its a cracked or leaky gasket, but if anyone can give me more input, it'd be greatly appreciated, thanks.

[Devil Inc]

Auto or 5-speed? If that makes a difference?

Bad expansion tank cap causing it to bleed off while driving?

[jlevie]

If a quart of coolant was going out the exhaust every 50-75 miles the car should be laying down a smoke screen like a WWII destroyer. Since overheating wasn't mentioned, it doesn't sound like the head gasket is leaking air into the cooling system, causing an overpressure and loss of coolant via the overflow. I suspect a leak, perhaps one that is only present when the engine is at temperature and the cooling system is under pressure, like perhaps from the water pump.

[bimmerboy12]

check heater hoses at firewall and other hard to see locations

[Rustyduktape]

thanks for the input guys. im leaning towards the water pump thing. it would make sense that no visible leaks are occuring when the guys just checking his engine, but when driving (when you cant look at the engine) and the engine is under a higher temp and pressure, it would probably be leaking then, so yeah, maybe the water pump or something. oh and its a 5 speed, if that does count for anything.