engine and drivetrain Still leaking oil - replaced exhaust manifold studs - SOLVED

[Healey3000]

Hi,

 

I replaced all exhaust manifold studs (using the shouldered kind), sealed the upper row with Loctite 242, allowed a 24-hour cure, used the proper copper-clad nuts and installed an IE Shorty header.

 

After about ten minutes of idling, I see oil running down the side of the block,  The larger stream appears to come from the rear end of the head, near the #4 lower manifold stud.  There's another, smaller stream from the #3 lower stud.  It does not look like the distributor flange seal is the problem, from what I can tell.  The attached pictures aren't the best, as the oil does not show up well.

 

I assume there are only three possible sources of oil - valve cover gasket, manifold studs and head gasket.  I don't see any oil from the valve cover gasket so either the studs still leak or the head gasket's leaking. Can I re-torque the head bolts in-situ?  Any and all ideas on the subject would be very welcome.

 

Thanks.

 

Update - It was the distributor flange after all.  The gasket there was a thick red/black paper laminate and did not look like a particularly good one.  Thanks to everyone for their ideas and suggestions.  I'm just glad it wasn;t the head gasket.

 

Back to driving!!!

 

Edited September 11, 2016 by Healey3000

[jgerock]

Let the engine cool down then rub a paper towel on the lower edge of the valve cover.  Some acorn style nuts will not tighten enough to seal the cover and gasket (they will bottom out).

[conkitchen]

If your bolt holes are drilled all the way through the head, you may see leaks. I always seal up the stud holes from inside the with RTV. Easy to do when the valve cover is off. 

 

But what do I know

[jgerock]

I've also read where some of the copper exhaust manifold nuts aren't sized properly for the M10 engine - they can tighten up but not actually tighten.

 

 

[Healey3000]

Thanks for the thoughts, folks.  Upon further examination and probing around, it seems that the rear right head bolt corner is where the large leak is from (the two rear ones are under oil pressure, I believe).  That's a reasonable distance from the exhaust stud to not be blowback caused by the radiator fan (I think).  Valve cover gasket definitely is not leaking.  The amount of oil that ran out from that rear corner suggests that it's a bigger leak than the exhaust stud would permit.  I'd expect slow seepage, not a couple of large drops hanging off the bellhousing in a few minutes of idling.

 

Looking through the records that came with the car, I see that the head was replaced back in 1995 (for $450!!) using gaskets FEL VS26046C and VIC MS15260.  I wonder if they used the new angle torque method on these head bolts.

[Buckeye]

you don't if previous owner re-torqued the head bolts after 600 mile when head was replaced.  re-torquing after 600 mile was standard procedure using old BMW cylinder head bolts torque procedure. AFAIK new head gaskets  Mfg's want you use torque and angle. If it was me I will use torque wrench to find out how close bolts are to final torque in old way specs was described.

[Simeon]

Loosen that head bolt, put some black RTV under the washer, retighten using the multi stage torque method. 

 

Been there done that. The washer leaves a small indent in the head from new. If this isn't put back EXACTLY as original it is a potential leak path.