I'm a fairly good mechanic but this one has me stumped.
The symptoms are that the car is loosing coolant and overheating. There are no visible leaks.
At first I thought it would be head gasket leak and so I did a compression test. The results were 175, 177, 165, and 165 psi.
That seems good to me for a 98 with 212,000 miles on it. The engine runs perfect and smooth when it is not hot.
When it gets hot it usually will not start until I let it cool.
There is no coolant in the oil.
I replaced the thermostat but symptoms are still the same.
I hate to pull the head if it is something I'm overlooking.
Any help would be greatly appreciated.
Thanks

 

my brother had that exact problem in his old 91 civic ... the coolant kept disappearing and it didnt show up in the oil either ... there were no leaks ... and it also would no start after the engine got hot ... the car wasnt worth fixing so he just junked it ... my opinion ... before you assume its a headgasket check all your coolant lines ... maybe get your cooling system pressure tested?

 

Thanks for the advice. The engine leaks the coolant out fairly rapidly so I believe that I would see it if it were leaking out a hose or something. No fluid on ground either.
Any other way for fluid to leave other than leak or head gasket?

 

Eureka! I think the water running down my drive would indicate the problem. Turns out it was a leaky hose. Since I had been using the garden hose to fill radiator I never saw the river. It is a small hose near the back of the motor so hard to see.
Thanks Funnyvictor86 for your help. Your diagnosis was correct and saved me a ton of work.

 

no problem