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4.0 help!


Mutant Pony

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2000 explorer, 4.0 ohv, Mysterious loss of coolant, Smoke on start up, Exhaust smells like coolant. NO combustion in the coolant. coolant system pressure test shows no leaks.
Cyl. #4 misfire, 150 lbs compression, Good spark. Misfire is intermittent.
Ford says it is a head gasket, What do you think?

I was hoping for an intake gasket. I will probably be pulling the heads tomorrow after noon.
 


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MAKG

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No combustion in the coolant? That sounds like an intake gasket to me, too.

I'd confirm with a leakdown test, just to be sure.
 

Mutant Pony

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Come on. The has to be some one here that knows something about 4.0s.

I don't.
 

MAKG

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What in your post is specific to 4.0Ls? What are you looking for?

Statements about "common" problems will only waste your time and money. You don't have the "most common" problem. You have whatever problem you have.

If your exhaust smells like coolant, you're burning it, whether this is a 1942 Flathead, a water-cooled Harley-Davidson V-twin, a 2000 pushrod 4.0L, or a 2008 Lamborghini V10. Your game is to find out HOW you're burning it.
 
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Bird

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Come on. The has to be some one here that knows something about 4.0s.

I don't.

MAKG already gave you a really good initial diagnoses - #4 cylinder intake port, being one of the corner cylinders is right next to a coolant port, is a good candidate for a leak if the intake bolts loosen ('common problem' ).


Bird
 

Mutant Pony

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It's about time I got a reply. Thanks!
I've read post after post about intake leaks. I've seen plenty of 4.0s with dead #4s. I couldn't find anything through oasis that said anything about intake leaks.
Is the intake gasket problem only in the early 4.0s or does it continue as new as 2000?
 

shadetree

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I don't know if Ford ever really fixed the problem or not. The bolts loosening is common, as is the bad intake gaskets. Many have stated they do not have loose bolts, but have bad gaskets. The gaskets get hosed due to the expansion rate of different metals.

If you get white smoke on start up, that indicates quite an amount of water. If I suspect water is getting into a cylinder, I pull the plugs, let it sit overnight, spin the engine over in the morning. It will blow the water out of the cylinder that is leaking. There are other methods, I know, but this one is as good as any. shady
 
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Mutant Pony

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I don't know if Ford ever really fixed the problem or not. The bolts loosening is common, as is the bad intake gaskets. May have stated they do not have loose bolts, but have bad gaskets. The gaskets get hosed due to the expansion rate of different metals.

If you get white smoke on start up, that indicates quite an amount of water. If I suspect water is getting into a cylinder, I pull the plugs, let it sit overnight, spin the engine over in the morning. It will blow the water out of the cylinder that is leaking. There are other methods, I know, but this one is as good as any. shady
That makes sense. I pressure tested the cooling system and didn't loose any pressure after 20 minutes. It doesn't seam to smoke at all after it has been running for a while. That first start in the morning will about kill ya though. I don't have the luxury of time though. Tomorrow I have to fix it. As well as replace a transaxle in an AWD Venture and a half dozen little jobs on the side.

Anyways, Thanks shady for offering something that I can use!
 

Mutant Pony

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Oh, One other thing. There is a white stain coming down off the #4 exhaust port.
I'm certain that the misfire is because of the coolant, I'm just not sure about where the coolant is leaking at.
The G.M. Intake gaskets I'm used to leak FAST, they are easy to diagnose. Of course if it is a G.M. it HAS an intake leak so the diagnosis is done! LOL!
 

MikeMcC

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That sounds exactly like the problem I was having.

It's very possible it's the head gasket or still possible is a cracked head. It's very common on the 4.0 OHV engine. You're going to be pulling the heads anyway to replace the gasket. I would have the head checked for cracks when your getting it resurfaced at a machine shop.

Mine turned out to be a failed head gasket and 1 cracked head.
 

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Actually, he's talking about the intake gasket, which is a distinct possibility. Sure, it might be a head or head gasket, but it's quite a lot cheaper to go after the intake.

It can be hard to confirm a lower intake, though a blown head can certainly be confirmed with a leakdown test. Good leakdown probably means a blown lower intake gasket, but it doesn't have to.
 

Mutant Pony

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A leakdown test won't tell you jack if your not getting combustion in the coolant.
It got thrown on a backburner till tuesday. I'll pull the intake and carefully scrutinize the intake gasket. If I find nothing that is clearly a leak, then I'll pull the heads.
I'll let you guys know what I find.
 

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It sounds like I have the exact same problem. What does combustion in the coolant mean? How can you check that? I'm sure I could replace an intake gasket but should I go and have a leak down test done before I just decide that is the problem? All the simptoms are the same.
 

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It sounds like I have the exact same problem. What does combustion in the coolant mean? How can you check that? I'm sure I could replace an intake gasket but should I go and have a leak down test done before I just decide that is the problem? All the simptoms are the same.
The easiest way is to fill the radiator to the very brim and leave the cap off... Then start the vehicle and if the coolant level drops out of the neck put a bit more in there while the engine is running.. you will be looking for small bubbles in the coolant.. if the level drops out of the neck you won't be able to see the bubbles.. if bubbles occur they are from the combustion, indicating a bad head gasket ot possibly a cracked head.
Big Jim:D
 

Mutant Pony

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We have a fancy, fandangled coolant/combustion tester. Bubbles in the radiator could just be an air pocket escaping but if it continues to bubble at the same rate and the level doesn't go down then, yeah, thats bad.
A leakdown test probably won't tell you anything at all.
 
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