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1989 Jeep Wagoneer, 360v8, 727, stock for now,
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Discussion Starter · #1 ·
Is it possible, probable that a head gasket can have an oil leak?
The new to me engine I bought (4BTA-130) has had a thorough steam cleaning but I see tell tail signs that this engine was/is a leaker. Under #1 exhaust where the manifold goes over a flat spot on top of the oil cooler, this area was hard packed, baked with oil crud. I can't imagine that this was just a fault of a leaking valve cover gasket. The whole right side of the engine had left over hard black spots that the cleaning didn't remove. The oil cooler on the R side of the block is the only part of the engine that has the original paint still on the bolts and gaskets, so I assume that this has not been touched. Every other gasket has been reused and sealed with a silicone gasket maker. I'm already committed to pulling the front gear housing and replacing the gasket so for pulling the head most of the stuff has already been removed.

Tappet cover gasket is being replaced too.

Tell me I wrong!
 

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It's possible but unlikely. Most I have seen like that is either the valve cover gasket, oil cooler gasket, turbo oil feed fitting, oil pressure sensor leaking
 

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Well, there are a lot of similarities between the 4BT and the 6BT and the 12V 6BT is known to leak in that spot. Its a poorly cooled spot on the block/head due to the proximity to the exhaust, minimal amount of steel there, and distance the coolant flows before getting to it. There are 2 passages head to block there; one for coolant and one for oil, and its a 50/50 shoot at which will leak. My own 6BT blew out the coolant passage there; it just slowly seeped coolant from that spot for a year or more and immediately burned it off on the hot exhaust. I finally went ahead and put in a new gasket and better head bolts that could take more torque and its been dry ever since.
 

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Is that passage pressurized oil or no? I'd imagine that you'd have oil pressure issues if you were leaking from a pressurized galley.
 

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The small oil passages between the block and head are pressurized. The returns are larger. Don't know that oil leaks on the head gasket are very common on the 4bt. However, if your head has enough warp, the gasket may not be seating properly. You see a lot of these engines that are an oily mess. Best to replace every gasket and seal, at least for peace of mind. Whether you pull the head or not is your option. I personally would do it. That way you can check the valves, check the head for warp, look for any unusual wear in the cylinder bores, look for any burned pistons. If all looks AOK, then the worst your out is a new head gasket and possibly new bolts.
 

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1989 Jeep Wagoneer, 360v8, 727, stock for now,
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Discussion Starter · #6 · (Edited)
From the Troubleshooting and repair manual B series 91-94:
"Lubrication for the valve train is supplied through separate drilling in the cylinder block. The oil flows through the drilling and across the oil transfer slot in the cylinder head gasket. From the transfer slot, the oil flows around the outside diameter at the cylinder head capscrew, across a slot in the bottom of the rocker lever support and up a vertical drilling in the support"
The larger bolt is used as the oil passage.

It makes me believe that the crud more that likely came from a leaking valve cover gasket?
 

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That is true but most of the time when the gasket leaks from the oil passage, it leaks the path of least resistance straight to the push rod opening. So you usually don't know til the head comes off.
 

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1989 Jeep Wagoneer, 360v8, 727, stock for now,
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Discussion Starter · #8 ·
Found the "Leak",

At least one of them, a major one at that, gear housing gasket drivers side.
 

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