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Coolant Leak, Intake Manifold?

Yankee516

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94 XLT, 99 5.0L AWD
Hi all,

I seem to have developed a moderate coolant leak on my 94 Explorer. After removing the air intake duct I was able to identify what I believe is the source. Maybe someone can confirm if this is indeed caused by a bad intake gasket:

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If it is, any guidance on fixing the problem would be greatly appreciated. Yesterday my 1997 BMW 540i wrecked in an accident and now I am down to one car (the Ex) and a house full of visiting guests... the spouse uses the 99 5.0L, so getting back on the road is going to be important.

I am pretty capable at working on the car and did the transmission last year, but getting to the intake seems to be a chore. If anyone has a procedure that would be helpful, as well as a list of replacement parts (e.g. gaskets) that will be needed. Also, are there any pitfalls in doing this?

Thank you in advance for all your help and advice. Take care!

--Phil

p.s. At least it isn't January!
 


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jd4242

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i would check the tq of the bolts.they have a tendency to come loose,that might stop the leak.if not then your looking at pulling the upper and lower intake off
 




Yankee516

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i would check the tq of the bolts.they have a tendency to come loose,that might stop the leak.if not then your looking at pulling the upper and lower intake off

That's where I'm at, JD. Thanks! Newest problem is that it is a lte model '94, so the Haynes manual is not accurate... Still trying to pull the upper manifold at this point, but VERY close :-/
 




jd4242

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That's where I'm at, JD. Thanks! Newest problem is that it is a lte model '94, so the Haynes manual is not accurate... Still trying to pull the upper manifold at this point, but VERY close :-/
its pretty straight forward.makes sure you use rtv in all the corners and recheck the tq a couple days later.good luck;)
 




Yankee516

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Thanks again! From what I can tell, the most difficult part is going to be reconnecting every electrical connection and vacuum line. Not easy to clear everything from the valve covers to the intake manifold and easily restore it all. I guess this is puzzles for adults ;) We'll see how it goes, and appreciate the advice! Cheers!
 




jd4242

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Thanks again! From what I can tell, the most difficult part is going to be reconnecting every electrical connection and vacuum line. Not easy to clear everything from the valve covers to the intake manifold and easily restore it all. I guess this is puzzles for adults ;) We'll see how it goes, and appreciate the advice! Cheers!

If you was getting any valve train noise/tapping and have a little extra cash,now would be a good time to replace your rockers .they are known to wear and tap.pretty simple to swap out and your have everything off and out the way;)one more suggestion would be to clean your upper and lower intake out real good,probably coated.check all vac lines for cracks also.:thumbsup:
 




justin_b31

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check for excessive water 'leakage' out the exhaust. if, like I had with my 93 explorer, you get a nice wet spot under the tailpipe after a few minutes of idle, you may have a cracked head.

in my instance the left head had cracks between the intake and exhaust port of two cylinders.

I suspect the area around the ports is just coolant, the oil channels are not here to show the tale tell sign of oil in coolant. But, the cracks were just enough to allow coolant to drip in the cylinder, vaporize during compression and firing sequence, and condense back to liquid at the end of the exhaust.

IIRC compression of all three was around 120 psi, not terrible for a 18 year old truck. Compression on my replacement head is now ~150psi

That said, the only reason I took the head off was because it was failing emissions for high hydrocarbons (unburnt fuel?) which was actually caused by severely recessed intake valves..two were recessed like 1/2"

Also, as the other posters mentioned, very loose upper and lower intake manifold bolts too..this was the first thing I tried for the watering exhaust
 




R&T Babich

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...That said, the only reason I took the head off was because it was failing emissions for high hydrocarbons (unburnt fuel?) which was actually caused by severely recessed intake valves..two were recessed like 1/2"...
How many miles were on the engine?
 








Allen35540

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I have been chasing coolant leaks in my 1995 Eddie Bauer Ford Explorer with the 4.0-liter ohv, (not overhead cam), V6 for some time now and after sealing the obvious leaks, a new one sprung up between the lower and upper intake manifold. Is there water going into the upper intake manifold or is the problem at the lower intake manifold gasket? Any suggestions on what this problem is?
 




justin_b31

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I have been chasing coolant leaks in my 1995 Eddie Bauer Ford Explorer with the 4.0-liter ohv, (not overhead cam), V6 for some time now and after sealing the obvious leaks, a new one sprung up between the lower and upper intake manifold. Is there water going into the upper intake manifold or is the problem at the lower intake manifold gasket? Any suggestions on what this problem is?

I was a bit surprised to see this thread come to life. Let's see if I can remember the assembly; I don't have the truck anymore for reference though.

So the throttle (throttle body?) attaches to the front of the upper intake. This is the assembly which mounts on the top-center of the engine. All this does is split the air flow, there shouldn't be any coolant that transfers between this assembly and the lower intake. Disassemble from lower intake by removing the eight or ten 10mm nuts along the top perimeter.

The lower intake, however directly attaches to the engine block and is the part that has the fuel injectors mounted right at the intake port. When I removed mine coolant was everywhere. This piece has the cooling channels to the heads on either side and down the center of the engine block between the cylinders and is the assembly which gets loose over time, you need the star sockets to remove/tighten the double-tapped bolts (the top threads point "up" into the upper throttle body and holds the bolts from the previous step; the bottom threads go into the engine)

SO, if you have coolant between the upper and lower intakes, I would think you have a different problem since there is no coolant transfer between these two assemblies. Perhaps you have a faulty water pump or failing o-ring at the temperature probe since that mounts near the upper intake.
 




Allen35540

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Thank you Justin!

A very good explaination Justin! This sounds like it's a bit complicated and I may have to take this in as I'm a little leary of ripping out the fuel rail and injectors at my age, LOL! It looks pretty much as you were saying, THANKS!
 




justin_b31

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I missed this, but I am pretty sure you're '95 is a Gen2, whereas this thread is about the gen 1 explorers; though the engine may be similarly built.

I too was worried about pulling injectors, but mine didn't go straight into the cylinders, rather they are positioned directly ahead of (and sprayed fuel) in front of the intake valves.

Actually the hard part was the engine wiring
 




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