OK, so I was having oil on the rear corner of the block, plug side of my 225, just under the head, on that little square protrusion. It ran down onto the tranny. At first I thought it was the rear seal leaking, this area appears to be dry.

I found that the valve cover was leaking on that rear corner, so I installed a new valve cover gasket, that's dry now, all the way around. Still I was losing lots of oil.

Then I found (special thanks to the SL6 boards for this one) the lower alternator bracket bolts were leaking oil around the threads, the oil was running back along the seam between the head and block, then dripping off the that same rear corner of the block, just below the head. Disassembled, cleaned everything, reinstalled with thread sealer. No longer leaking there. I figured I had it licked. I was really feeling good at this point. BUT....

I drove it for a week, checked again, and I was disheartened to find that there's some fresh oil drops on that rear corner of the block. The plug tube seals are not leaking, the valve cover gasket is not leaking, the alternator bracket bolt leak issue is resolved.

Where is this oil coming from? I doubt it's a bad casting, and head gaskets rarely leak (this is a new head gasket and rebuild). I checked the torque on the head bolts when I had the valve cover off, they're good. I'm stumped. There is a small oil galley plug down below that rear corner on the side of the block, so just to be thorough, I pulled that, cleaned threads well and reinstalled with new thread seal. Still, even if that were leaking that's well below where I'm finding oil. I assume the oil must be either running down onto that rear corner from above, or running from front to back along the head/block seam (as it was from the alternator bolts). It could possibly have been blowing up from that plug when I'm flying down the highway, but that's a stretch. I can't isolate the source of the oil. I run my finger along and under the entire lip of the valve cover, even tried a dry paper towel, no oil, very dry. It's not coming from the PCV or cap, otherwise the valve pan would have oil on it, but it's dry as a bone around that area. The plug tube seals are dry, and area around the tubes is dry.

Did I mention that I hate oil leaks? At least I've stopped a couple sources of leaking, but still there seams to be another source. What am I missing?

Thanks for any insights anyone might have.

'67 Dart 270

Head gasket where it goes around the lifter galley. You will find most after market head gaskets have a small bead of some sort of sealant on the most outboard side.

Richard

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Part of Tyrde-Browne Racing

Still frustrated.

I did notice that some oil was leaking from around where the PCV grommet was, so I sealed that. No leaks, but....there's still oil on that back corner of the block, just below the head.

Could this be the head gasket leaking oil? I had the rebuild done with a marine 225 heavy duty head gasket. I suppose I should isolate the leak source before pulling the head...

Could the oil pump cover or sender be leaking and oil is running up the block when I'm going down the highway, i.e. air currents flow upward on that side of the block at high speeds? I did find some oil down under where the oil pump bolts on, but I figured that was from dripping down, not up....

thanks for any insights.

BG

Nearly every slant six I have had has leaked from that spot. I have tried numerous head and head gasket combinations, Fel Pro and Victor Reinz gaskets, and the only thing that seems to slow the leak down or stop it is to smear that union with RTV sealant.

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Casually looking for a Clifford hyperpak intake for cheap.

I always use sealer along that edge.
DD

So I should pull the head, new head gasket and sealant along that edge? Or is there a way to seal from the outside?

thanks all,

BG

Absolutly confirm that this joint is the leak point.
Were both the head and the block deck resurfaced during the engine rebuild.?
DD

Hi DD,

The head and block were both resurfaced in the rebuild. i doubt the engine rebuilders know all the particular tricks and quirks of the slant six.

No, not sure its this source, but the symptoms seem to be pointing in that direction as I've isolated and fixed other leaks and this one persists.

Perhaps I should try the fluorescent dye to track it down for sure?

BG

OK, I've isolated the leak, it is definitely leaking from between the head and block, on the plug side, so it must be where (DD) always applies sealant during assembly. My engine has a good warranty, this should be covered. I have no idea whether they also apply sealant there prior to assembly.

Question: what is the best head gasket to use? Also, I see some vendors make head gaskets with pre-applied sealant around the oil galley areas, does anyone know if these work or should I go with tried and true sealant application as DD suggests?

thanks so much,

BG

Why chance it--
go with tried and true sealant application as DD suggests.

Richard

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Part of Tyrde-Browne Racing

Mine did the same thing......use Doc's sure fire method.
I don't think my block was decked a smoothly as it could have been on the last milling pass.

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Aggressive Ted

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