Thanks for the reply Ulysses. After replacing my thermostat, I only
noticed
one thing when driving it for about 100 miles. My check engine light
clicked on for a second and was off again. The temp gauge did not move
from
its normal position(which is midway) after it was warm. Once cooled, I
checked my coolant and it was down a little. I am still leaning towards a
failed head gasket or heads. I will let the group know what I find out.
"Ulysses" <eatmyspam@[EMAIL PROTECTED]
> wrote in message
news:3KuIj.24078$XA.8621@[EMAIL PROTECTED]
>
> "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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