Could go either way at this point. Once it has cooled off and you have
corrected the cause of the overheating, you can do a "shadetree" test. With
the engine cold and off, remove the radiator cap and start the engine. Pinch
off the tube to the coolant reservoir and place the palm of your hand over
the radiator opening. If you feel steadily rising pressure within five
seconds or so, or (worse) pulsations, it is pretty certain you have a warped
head... maybe both. If you don't feel pressure on your palm within 15
seconds or so you should be okay. Of course, you will feel rising pressure
after a minute or two from the engine warming up, so don't confuse the two.
The definitive test (necessary if the first one gives you bad news) is to
put air pressure in each cylinder and check for rise in the coolant level or
bubbles in the coolant. That will determine which - or neither or both -
head(s) is/are at fault.
The definitive test is that after driving several miles at short and long
trips, the engine doesn't lose coolant.
As things heat up, they expand. If there are cracks in the heads, the cracks
can open up. As things expand, cracks or leaks that aren't present when an
engine is cold can open up.
Although that can have false positives - anything that was disturbed by the
overheating can cause coolant loss, and often these episodes are caused by
coolant loss in the first place. It can also have false negatives -
sometimes the coolant loss isn't obvious, even though exhaust gases are
carving out a channel through the head gasket. But I agree that the engine
isn't out of the woods if coolant is disappearing anywhere.
thanks for your help guys. i replaced the coolant and drove the car
all day today and it did fine i was just mainly worried blowing a
headgasket and warping the heads (already replaced once...it was
beast) but it seems to be doing fine. thanks again
"Michael Pardee" wrote:
> > The definitive test is that after driving several miles at
> short and long
> > trips, the engine doesn't lose coolant.
> Although that can have false positives - anything that was
> disturbed by the
> overheating can cause coolant loss, and often these episodes
> are caused by
> coolant loss in the first place. It can also have false
> negatives -
> sometimes the coolant loss isn't obvious, even though exhaust
> gases are
> carving out a channel through the head gasket. But I agree
> that the engine
> isn't out of the woods if coolant is disappearing anywhere.
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It kinda depends on which engine, too. My '93 Cougar V6 stopped making heat
one day last spring. When I checked, coolant was low. When filled back up
and bled, the pressure cap would release every time the engine was goosed
over idle. Big bubbles into the overflow tank. $1700 later, after head
gaskets, valve job and timing cover seal fix, she is good as new!
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