Ford Repair: 97 ford motor trouble., combustion gas, head gaskets

Question
Hi there.

i have a 97 f-150 with a 4.2l V6. the truck has got close to 250,000 Km, but untill recentley i have never had any trouble with it. the problem i have is this...

first of all, i have difficulty when starting it. it cranks several times before firing, and when it does fire, it runs very rough for a few seconds. after that it runs well. i have also noticed a decrease in both milage and power.

occasionally on start up, it will smoke/ steam in the exaust, but this never lasts very long.

also, i find that i loosing anti freeze, but i dont know where (presumably burning it off?). the antifreeze itself has a sour/ chemical smell which is NOT normal.

i am very echanically inclined- i've rebuilt lots of motors, my problem here is tracking the problem down. i'm leaning towards a head gasket, but my compression tests come up pretty normal.

thanks for any wisdom you may have- thanks   andy.

Answer
this engine was known for two things, intake gaskets leaking and yes, head gaskets. best advise i can give is either put a pressure test to the cooling system and look for external leak. you may see a small one from the timing cover but won't cause driveability problems. you can also purchase a combustion gas tester from any local auto parts store. they're fairly cheap. you place the tester either directly on the raditor ( where the cap would be ) or the overfill bottle. The chemical in the tester will turn from blue to yellow if the heads are blown. keep me posted