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Oil leak from N/S cylinder head gasket.

Posted: Thu Dec 05, 2019 7:29 pm
by DaveEFI
I've been trying to sort out loads of oil leaks from my very high miles SD1 EFI. It could really do with a 'new' engine, but it still goes very well indeed.

I've done the front crank oil seal, and rocker covers. But it was also leaking from the sump - so have had that changed at a local garage, as the car lives on the street. They steam cleaned it, and reported a leak from the N/S cylinder head gasket too. But they've changed the sump one.

A few years ago I bought some stage1 heads which had been planed down for composite gaskets and the surface looked excellent and flat checked with my straight edge. Composite gaskets came from a local spares place.

On advice I left out the third row of bolts. And used new ones to the correct torque, and the correct Scotchclad sealer.

Should I have fitted the third row and just nipped then up? Or could it be a cheap gasket? Or anything else?

Re: Oil leak from N/S cylinder head gasket.

Posted: Thu Dec 05, 2019 8:34 pm
by ChrisJC
In my experience, oil from the valley area will travel slowly across the deck and leak out where head meets block under the exhaust manifold.

To fix this, I run a super thin smear of instant gasket along both sides of the head gasket all along the valley side.

So far so good...

Chris.

Re: Oil leak from N/S cylinder head gasket.

Posted: Sat Dec 21, 2019 3:41 pm
by ratwing
This reply is a bit late but I assembled my 4.6 with Elring head gaskets and had the same leak - I had a spare set of Elrings which I coated with copper spray and that cured the leak. (there's a previous thread about head gaskets leaking oil)
I don't know how easy it is to clean off copper spray so maybe silicone would have been a better choice?

Re: Oil leak from N/S cylinder head gasket.

Posted: Sun Dec 22, 2019 8:30 am
by jenand40
Dave, would be interested to know what Scotchclad sealer is and where it was applied.
Andy.

Re: Oil leak from N/S cylinder head gasket.

Posted: Sun Dec 22, 2019 10:09 am
by DaveEFI
jenand40 wrote:
Sun Dec 22, 2019 8:30 am
Dave, would be interested to know what Scotchclad sealer is and where it was applied.
Andy.
3M Scotch-clad 776. It's the sealer recommended in my first Rover V8 factory manual, for a P6. It seals a thread that goes into the water jacket, locks them, and prevents them corroding. The small water pump bolts will pretty well always shear off on removal without something to stop them corroding. I use it on all the threads that go into ally. At one time, it was a Rover part.

You simply dip the thread of a clean bolt in it just before assembly. There are bound to be alternatives today, but a litre tin of it is enough for several engine rebuilds, and it keeps well, so I've stuck with it. To clean old bolts that have it for re-use, you simply soak them in cellulose thinners.

Re: Oil leak from N/S cylinder head gasket.

Posted: Sun Dec 22, 2019 9:07 pm
by jenand40
Thanks for that Dave.

Re: Oil leak from N/S cylinder head gasket.

Posted: Tue Jan 14, 2020 7:40 pm
by Mc Tool
I have previously had sealing issues with tin type gaskets (it was a honda vfr 750 and new gaskets were nearly 400 bucks ) and after trying a few expensive potions that didnt work well the bike shop man tells me just spray a bit of aerosol paint both sides....worked a charm.