"Lance" <phantom523@[EMAIL PROTECTED]
> wrote in message
news:jb2dndvthffcqmzanZ2dnUVZ_sCtnZ2d@[EMAIL PROTECTED]
> All,
>
> I have a 1999 Explorer 4.0 OHV. Mileage is around 135,000. Had the
heads
> replaced around 120,000. Both heads had a fine crack. This was done
about
> 14 months ago.
> Fast forward to 3-20-08. While driving the Explorer after it had been
> sitting for a few hours and engine was cold, the temp gauge would rise
to
H
> and go back to the mid point where it always would rest at. When I
reached
> a safe spot to pull over, I checked under the hood and my radiator cap
had
> released some coolant. After it cooled off, I checked my level in the
> radiator and the coolant tank. Both seemed fine. Started back up drove
for
> until it warmed up, same scenario, except this time, it came out the
coolant
> tank. Now, it has not overflowed out of the radiator cap or coolant
tank
> anymore.
> What I have done is replaced the radiator cap. Replaced coolant lost
during
> the times it overflowed.
> Will replace the thermostat today thinking that it may not be opening up
> like it should.
> Any ideas on what else would cause it to heat up rapidly and steady off
on
> the gauge. I thought the gauge may not be reading correctly, but if
that
> was the case, would that cause the engine to send coolant out the tank
or
> the radiator cap?
> I was thinking the heads that were replaced may be having issues that
are
> the root cause. If the heads were cracked, again, or gasket issue,
would
> that let combustion gas into the coolant and cause it to heat up? But,
if
> that happens, why would the temperature gauge go back to reading normal?
>
> Thanks for any suggestions.
>
> Lance
>
>
Since you had the heads replaced I would suspect the radiator cap. But
since you replaced that I would suspect the heads or head gaskets again.
My '91 will do that with the temperature gauge but I think it's just my
thermostat getting stuck when the engine is cold. To me it sounds like
they
may be two different problems. Flu****ng the cooling system might help. I
had success using some radiator stop-leak on my Explorer but I only used
about 1/4 can and it seemed to take care of the leaking heads. Too much
stop-leak and it might clog your heater core etc. But it might tell you
if
you do indeed have leaking heads. From what I've read if you do a
compression test head leaks usually indicate low compression on one
cylinder
or two adjoining cylinders. Supposedly there are tests strips you can get
at auto parts stores that will test for exhaust gases in your coolant but
I've never used them.
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