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circumstantial evidence

i looked at an '02 mazda 626 today.
It has 71xxx miles but is overheating and has a misfire.
Both the front wheel bearings are loudly roaring.
The LF engine splash shield is missing.

Carfax OK'd this car a few years ago. It's been mostly fine until now i'm told... at least about the overheating and misfire. It needed a battery a while back.. decent car.

Logic and gut tell me it may have a bad head gasket due to the symptoms. Specs, age, and mileage tell me it should be something else. If only the symptoms would agree....

I fixed the misfire i think. Time will tell. Plugs @ 60K are recommended. I replaced the chewed up 'fan' belts too.

The coolant loss symptoms point to head gasket, but they don't scream it. I like it when they scream.

Coolant loss seems to be only coming from the cap releasing pressure... but it seems to build pressure prematurely.
It has slightly low compression in the left bank, specifically the center cylinder there. That cylinder had a VERY difficult to remove spark plug... like it was extra corroded.
"Technically" the comparative compression between the six cylinders is OK... within 15% of each other.... but the right bank is nearly dead equal between the three, and the left bank is lower, with the center cylinder reading lowest.... It's right on the line... 15% exactly.
I wouldn't bet my life on it being a head gasket, but I'd bet on it. I wouldn't bet on anything else unless someone gave me a good enough reason.

Sean came home.
I presented it to him 'cause he's real smart.
"I looked at this car. When it came in, the temp gauge didn't read hot, but it was bubblin' from the cap, and the cap fits and tests good."
"head gasket" said he.
Then i presented the age/mileage and lack of conclusive evidence (and trying to avoid the inevitable), and he hemmed and hawed like i, but still leans towards head gasket. We like it when they scream.