I have a slight oil leak at the back of the engine. I've ruled out valve cover gasket and half moon plug because the head under balve cover is completely dry. Yes I did apply gasket maker to plug.

It seems to be coming from the egr pathway plate at the rear of the head. I know the function of this plate. But does it also block off any oil passages? I've searched and got mixed answers on this. Is there anyway oil could be leaking from there?

Pic from google

 

In theory there should be no oil .

A bad spot in the head casting after all this time .

It has been a while since I had one of these engines apart I should have a head floating around I just need to look again to double check.

 

It may be possible to use a small dental mirror to verify where the oil is coming from. Time to hit the dollar store.

 

Did the plenum have oil residue in it? What shape was the PCV valve in?

 

There was no visible oil residue in plenum when installed. Pcv seemed good but replaced recently anyways.

 

Okay. So, there wasn't a lot of oil in the valve? I'm only asking because oil flow restriction can cause higher oil pressure pushing oil into areas where it shouldn't be. Or out of seals when nothing's wrong with the seals; ie, aged and cracking. That's all.

 

Ahh I see what you're gettin at. I've still got it so I'll take a look in a minute. So if it's got a lot of oil in it?

 

The only back there is from the valve cover of half moon block. Too high up for anything else.

 

Okay little update.
I went ahead and replaced VC gasket and half moon plugs. We'll see if that does the trick.

Before I replaced those multiple times I cleaned and inspected to try and find where leak is coming from. Seems to be coming down the driver side of transmission and dripping down on the ground from bottom of transmission. Also this isn't a huge leak. When I park it for the night and come back out in the morning the oil spot is about the size of a 50 cent piece. But does not leak when off or just idling.

I can't get it to leak just sitting here idling. Only will leak if I take it for a spin. Hoping it's not rear main/rear main gasket. I don't think it is seeing how it's visibly coming down from about transmission. The EGR pathway has lots of fresh oil on it.

Cleaned everything up and Gonna take it for a spin.

 

You ever figure this out. I seem to have the same type leak on my 88 2wd and I am planning to pull transmission but not 100% sure it is the rear seal.


22R88

 

I had the same leak on mine in the same place. It was the valve cover gasket. Seems oil will pool in the head towards the back and for some reason it finds a way out there. Drip out between the gap of #3 and #4 exhaust. Mine was a bigger leak so it was easy to find. If its not that then you have big problems with your head!
If oil was coming out of that back plate on the head then you would have noticed it also big time when you removed the egr valve [which I see is removed]
Replace the gasket and see, clean up around there real well before you do. Easier to find leaks when things are clean.

 

When I replied valve cover gasket and half moons it took car of oil leak at the back of the head.

But I also then realized my rear main was leaking. Re did that about 2 months ago. And I'm now leak free!