Coolant Leak

[vintageracer]

Last Thursday I purchased a 1999 302 V8 Eddie Bauer Explorer. Hard loaded with everything but 4WD.

The lady from whom I purchased the truck said it had a coolant leak. She had a mobile mechanic come over to her house to repair the truck. The mobile mechanic removed the top part of the engine down to removing the intake manifold (air cleaner, plenum and intake). He never returned!!

The lady had no idea from where the coolant was leaking. Since the mobile mechanic removed the intake this brings up several questions concerning the possible location of the coolant leak. Intake gaskets? Head Gasket? The thermostat housing that can and does go bad on these trucks? I DON'T KNOW???? The radiator, fan, water pump, timing cover, valve covers, thermostat housing and more are all untouched and still in place. I am not sure what the mechanics reasoning was for removal of the intake.

Therefore my questions:

Are the 302 engines in 1999 Explorers known for blowing head gaskets.?

Are the 302 engines in 1999 Explorers known for intake manifold gasket leak problems?

Am I missing something and could there be another coolant leak problem for which you would need to remove the intake manifold?

I look forward to your responses!

[embler]

I would get pressure tester, put some pressure in the coolant system and see if you find out where its leaking from. Never heard of them having problems with head gaskets and such.

[PaceFever79]

Hard to say so many possibilities. But the intake manifolds can corrode and leak if the antifreeze isn't kept up. Usually it will weep out (any) of the tie down bolts.

[vintageracer]

I would get pressure tester, put some pressure in the coolant system and see if you find out where its leaking from. Never heard of them having problems with head gaskets and such.

Thanks for the suggestion as I had considered that option however I would have to re-assemble the engine to do a pressure test therefore I was just wondering if anyone had any experience with coolant leaks on these engines and possible locations.

At the current point of engine dis-assembly all I have to do is pull valve covers, exhaust manifolds and heads to replace the head gaskets and re-assemble the engine with new manifold gaskets OR do I just re-assemble the engine with new manifold gaskets and see what happens and see if the leak is solved?????

[Haystack]

Why replace the $100 set of head gaskets if you don't know where it's leaking?

Throw only the lower manifold on and pressurize it and see what happens.

[83gtstang]

If it's anything like my 96. Mine was leaking from the water pump heater inlet and outlet tubes. They corroded apart when I tightened the hose clamps. Be prepared to break bolts in the timing cover and intake bolts in the heads. I completely replaced the timing chain and cover as well as the water pump and all bolts. Be sure to use antiseize. Also a problem is the transmission cooler bursting into the radiator coolant contaminating the radiator with tranny fluid.

[JACook]

The bolt breakage is generally only a problem if someone removed them before you, and failed to coat
the threads of the four long bolts with a proper sealer. Anti-seize is fine for exhaust bolts, and bolts that
thread into aluminum, but won't help as much with bolts that have coolant on the other side of the hole.

I've never had an issue with those bolts if they were factory installed, or had proper sealer applied to the
threads. I prefer to use Oatey white teflon pipe thread paste, as it's a dead ringer for the ARP thread
sealer, but way cheaper.

Always use a pre-mix of 50% coolant with 50% DISTILLED water. I buy the full-strength coolant and mix
it down, rather than paying coolant prices for the whole gallon of the pre-diluted stuff. Keep a jug of the
pre-mix on hand to top up the system, and avoid ever adding straight water. Aluminum parts start to
corrode long before any sign of rust will show up in coolant that is too watered down.

[gt pony]

Check the water valve in the heater hose line from the heater core. You should see coolant residue at the underside of the valve and possibly below it. This was a pretty common problem on Explorers in my neck of the woods.