I think I posted about this car earlier asking about it's estimated mpg... but new topic:
It's got the SOHC B6 Mazda 1.6L in it, engine was working but then started stumbling (previous owner) and I found water in the oil, and air bubbling out of the radiator under pressure. This with a cold engine.
I pulled the cylinder head, and the most of the non-metallic bits of the gasket are stuck to the block and head (haven't scraped yet), but I dont see where there was an obvious leak. No discoloration around the bores, and no obvious leaks between oil and water passages either. I CAN tell however the head has been off before. It was missing a washer on a head bolt, and the exhaust wasn't rusted on. Some of the exhaust and intake bolts were replaced with studs, I dont think that's stock. Exhaust gasket looked good, intake gasket got bits stuck to the manifold and head.
So far I have 50 cents invested in this car. It's got ~180k miles, the cylinder walls look pristine, and it's got a 5 speed (good hypermiler? )
The headgasket set is $60. I'll need a timing belt too now. Should I put a gasket in and hope it fixes it, with the risk of the head being cracked instead? Any ideas what it costs to get a head pressure tested so I can be sure? I could probably find a used head cheap enough if I can get it tested cheaply...
The machine shop I use would charge about $100 to hot tank, check for cracks, mill it flat and grind all valves/replace valve stem seals (you supply the seals).
It could be that the head is slightly warped and not allowing the gasket to seal properly. Milling the head would solve this- unless the block deck is warped. You could use a machinists straight edge to check this. Normal service limit is .003" max (for a Honda 1.5L of the same year). The motor would have to be pulled and the block stripped in order for it to be milled.
You could possibly buy an engine that is guaranteed to run and not knock from a junkyard for about $300 (at least that is the typical junkyard warrantee). Check car-part.com.
Did the engine block have anitifreeze in it or plain water? If it was only water and you live in a "cold" area the block is likely cracked...
I haven't checked the block yet, the old school engine builder I'm getting local advice from says it's a cast iron block and I shouldn't worry about it...
He said the previous mechanic who changed the gasket did it very wrong, he reused the stretch bolts and probably torqued them in the wrong order, warping the block, and causing premature re-failure of the gasket.