Strange oil leak?

[Chris Taylor]

I just rebuilt the motor in my daily driver T and noticed a strange oil leak. I have drove the car 20 miles now and noticed a drop of oil under the car. It is dripping from the deck above the starter heat shield.

This is what is strange. The valve covers are not leaking. I can see all around them. So I thought it may be the back of the intake where the intake meets the head. I is dry as a bone. I have built over eight of these motors and never had an oil leak. My GN motor has been together for eight years now and no leak. I am baffled over this leak. It looks like the oil is weeping from the head and deck of the block at the corner of the block. I know there is not oil around this area. I thought there may be some porosity in the block behind the bolt hole where the heat shield bolts above the starter. It is dry and OK. I decked the heads and the block as always when building a motor.

There is no oil leaking down the back of the heads or block every thing is dry except for the one small area. I have looked under the car while it is running and the oil will not start leaking until the car is driven. This means this is a windage problem. Anyone ever ran into this problem before?

 

[FJM568]

Check your connections at the oil pressure sending unit/turbo oil feed line...A leak there may not show up until you start driving due to oil pressure being higher while driving and oil being blown back along the side of the block from there to the starter heat shield...

 

[Chris Taylor]

Jim, thanks for the idea. That is the first place I checked. It is dry as a bone except for the one small area. I took the turbo, header and D/P off to see easer. This is strange. It is at the back of the block and head right where they meet.????

 

[Chris Taylor]

Has anyone ever had a leak like this?

 

[Buick Mark]

I have the same type of leak, it seems to be dry everywhere, but it drips from the starter heat shield.
The only thing I've been able to figure it might be is the head gasket leaking around the oil drainback holes that go into the block. Mark

 

[Chris Taylor]

Mark,

I was thinking the same thing. If it was leaking in this area you would think it would run down the back of the head and deck of the block. This would be leaking at the corner of the intake and head. I have been back in my shop today all under this car and still can't find where this leak is orignating. The only place I see oil is where the head and block meet above the threaded hole where the heat shield bolts to the block. I have removed the transmission, header, DP, starter, crossover pipe, trans dust shield, everything to see where this oil is weeping. What a mystery???

 

[KWIKR 1]

I just went through the same BS thing on a recent new rebuild . I even GM oil traced it . Back of intake looked dry , I changed the oil pump o ring , valve cover gaskets,replaced turbo oil return fittings .Small Oil drips were comming of off the starter shield and could be seen on the bottom of the starter bolts as well . also on the bottom of the heads up front and comming off of the bottom of the frost plugs. I was under the car for 2 weeks banging my head against the wall trying to figure it out . I decided to reseal the intake . And that was it !!!!!!!! I resealed it with the stock rubber seals and a dap of the "Right Stuff" in the corners . All is dry . now if I can only find that knock problem I'll be set .

 

[Chris Taylor]

I am thinking it may be the intake. I still think I would see oil running down the back of the head or deck of the block. I can't figure how the oil is tracking to this point.

 

[bob86gn]

Chris,

I have the same problem. My heads leak like a sieve. Block and heads were dead straight but it looks like the back of the head is leaking right where it meets the block. What head gaskets are you using?

I am going to try retorqueing my heads to see if it helps.

Bob

 

[KWIKR 1]

It's the intake ! . I'll bet a case of Canadian beer .

 

[Chris Taylor]

You would win that bet. It is leaking at the back corner of the intake/head. I drove the car 12 miles and found it when I got back to the shop.

 

[KWIKR 1]

Glad to hear it . The same thing drove me nuts for 2 weeks trying to figure it out . The oil looked like it was coming from everywhere but the back of the intake .