1979 Other Chevrolet Models Engine Oil Leak.

D.T. BENNER

MEMBER
1979 CHEVROLET
V8
2WD
AUTOMATIC
9,000 MILES

I have a rebuilt Chevy Small Block 350 V8 engine in my Hot Rod that has an Oil leak that shows up as oil dripping off the starter bolts. I redid the Intake manifold and I'm sure the RTV sealant at the back of the minifold is NOT leaking. Same for the valve covers and Oil Pan.
There seems to be Oill present at the head gasket area above the 2 rear exhaust ports on the right rear of the engine. I have been told that there is No pressureized oil in this area of the head/block interface but it's the Only place where fresh wet oil shows up?
Could it BE the head gasket leaking oil? Has anynoe else experienced this?
This is driving me Nuts as the car is a show winning Hot Rod and Oil Leaks are Not what I need.

5 Replies

HMAC300

MECHANIC
48,601 POSTS

Look carefullly along the rear china wall(rear of intake on bottom). Or check the oil pressure sending unit which is at the rear also. Those are the most common areas for leaking and following the head gasket. It can also be the the head is warped as I don't know if the head was milled or not. You can also try retightening the head bolts (65 ft. Lb.) Also there were bars that go under the valve cover bolts to spread the load on the valve cover.

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Friday, October 8th, 2010 AT 8:08 PM

D.T. BENNER

MEMBER
3 POSTS

Thanks for the reply. I to have 40+ years experience as a mechanic (but not on Small block Chevy V8's) but this leak is a new one on me.
I have this engine in a Hot Rod Show Car and it is clean enough to eat off of so an Oil Leak is especially noticeable.
I did make sure that the Intake dams are sealed well and the Valve cover gasket and Oil pressure sender are not leaking (or the base of the distributor) and there is No Oil along the rear of the joint between the Head and the Block.
I have been told that there is No way Oil could leak from where it seems to be coming from as there is no pressurized Oil going from the Block to the head in that area.
I'll try re-torquing the head Bolts and if that doesn't help I guess I'll have to pull the Head and replace the head gasket.
Anyone ever see this problem with Small Block Chevy's?

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Friday, October 8th, 2010 AT 11:48 PM

HMAC300

MECHANIC
48,601 POSTS

I as well have over 45 years of being a mechanic. 24 of that was spent working at Chevrolet engineering specifically in the engine dept after test. Usually leaks of htis sort were from where i've said. There are not pressurized areas on those places on teh engine. If you siliconed the dams then it should have taken care of it. However it was found that a little silicone should be applied to the bottom are of the intake gasket where it meets the block. Also I don't know if the head was haved or not or what type of head gasket you used. If it is the thick gasket then it's ok to install dry, but if you used steel head gaskets, then it should have at least a spray sealer substance applied to it. Chevys are just like the other motor, they have their quirks but small blocks are pretty good. If you do pull the heads off you couldput teh 94-96 truck head on with no problem which would give you the new high rail design and are the best flowing stock head as well. However it woud require new valve covers. You coud also use any thing from 87-96 cylinder head as well. After 96 the bolt pattern changes on the intake. Good luck.

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Saturday, October 9th, 2010 AT 11:20 AM

D.T. BENNER

MEMBER
3 POSTS

Thank you for the reply. I didn't build the engine as it was in the car when I bought it. Has Flow Teck Aluminum heads on a 70's 350 block bored and stroked out to 383 Cu. In. Head gasket material is unknown but I think this winter I will pull the right side and replace it.

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Sunday, October 10th, 2010 AT 12:57 AM

HMAC300