Most common reason is a blown head gasket, then a rare cracked block or
cracked head.
Easy to verify without disassembling engine: go to auto parts / speed
shop. Get some carbon monoxide test tablets and put into radiator, run
engine for several hours, shine 'black' (UV) light into radiator and
look for fluorescence caused by the indicator chemical (tablets above)
when it binds with the CO.

If you run hard and 'shut down fast' without letting the engine self
cool by idling back to normal temps .... then expect a blown head
gasket. Of course you probably dont retorque the head bolts yearly
like you should if you are running a lot of WOT.

In article , BSCHNAUTZ
wrote:

Bruce makes a good point. one other thing is that you could have a cracked
head...but not causing any noticable performance difference.

it IS possible for a head to have a ever so minute crack in a water chamber
that would cause coolent to leak (under pressure) down an oil return hole, or
pushrod hole.

One thing you could do is pull the spark plugs and examine them. if coolant IS
getting into sa cylinder, then a spark plug check can tell many tales, and
show
you a cylinder you are having trouble with.

Tim



I would first look at Head Gasket, then look at cracked
head and finally cracked block. Cracked block would not happen in the
middle of the season, unless you had a Coolant FREEZE during that time
period, Cracked head, maybe, but still very unlikely for the same
reasons, except could happen if you overheated the engine recently.
Bad Head Gasket can happen anytime, and is also not to hard to deal
with, except it will require a topend disassembly, which is also
what is required for a cracked head.