oil leaks

[philip j]

Chasing oil leaks.



I have my engine torn down to replace the cams.
I had several rocker shaft leaks, but I did have RSR seals already, I'm
assuming that the hole the shaft goes into has a sharp edge and may have cut
the seals as they were installed. I'm thinking of slightly rounding over the
edges. This means that I should probably remove the towers to do this. I
will use new seals any other suggestions?

I have head to cylinder weeping leaks. I'm not quite sure what to do on this
if anything I'm already 1-2lbs over torque of 36ft/lbs. (I just did a
re-calibration of my torque wrench) and I don't really want to increase
torque. Some of the center leaking may be part of the rocker seal leaks but
the leak on 1 and 4 are not from the rockers.

(ARP head studs, Xtreme heads and replated cylinders JE pistons were lapped
in and fire rings looked good, all low mileage)

Any thoughts on this?



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[philip j]

[philip j]

[philip j]

[philip j]

[jpilcher]

Hey Phillip

Check out the Nick Fulljames video on cam timing.

N Fulljames cam timing.wmv - YouTube

He installs the RSR seals around the 6:05 minute mark. Hope this helps.

Regards

John

[Black_Hat]

looks like cly to head sealing issues .

did you lap the heads to the cly with valve lapping compound?

[philip j]

Originally Posted by Black_Hat

looks like cly to head sealing issues .

did you lap the heads to the cly with valve lapping compound?

Ni-resist rings on new surfaces, all looks good, and second time apart. Looking for some advise from someone that's been through this before. Running 1 bar boost. Philip

[Black_Hat]

I trust no one and will lap newly machined cly to head even with Ni resist

some machinist blue and a quick spin by hand will tell you if the work was done correctly and if you need to lap some more to get it perfect.

[Lapkritis]

Looks like it might be from the exhaust rather than the cylinder head/cylinder. The tar/slime is common if you have a small leak at the flange where the exhaust manifold contacts the head. You can see some of the staining around the exhaust ports...

[lindy 911]

So Lap, you're suggesting that he has an oil leak from his exhaust manifold? Where would the oil come from if that were the case? Surely not the guide seal as the oil would burn off first.

[philip j]

Yes , heads were removed last year (same leak) and were cleaned and lapped.
fire rings looked good and fit well.

The heads are built by Xtreme with oversize valves and 8mm stems, real low
miles so the seals shouldn't have much wear.

[Lapkritis]

Originally Posted by lindy 911

So Lap, you're suggesting that he has an oil leak from his exhaust manifold? Where would the oil come from if that were the case? Surely not the guide seal as the oil would burn off first.

Yes, I can explain a bit further. A leak between the exhaust manifold and head can cause tar to leak as pictured. When the engine is cold and running rich after start-up, you'll get condensation and hydrocarbons that combine with oil to make a slurry type mixture. It's not hot enough after the start to burn it all off before it escapes. The tiny (or large) amount of oil in the combustion chamber or exhaust port is all it would take to produce what we see in the photos. I have this exact problem on my turbo car right now... quite common.

[Lapkritis]

Originally Posted by philip j

Look at the valve for #5 (white) and then for #6 (leaker). There's oil in the exhaust port here. Generally you'll have bubbly black soot on the bottom of the guide if it were dripping down from the stem seal. I would suspect oil blow by or just oil sneaking by the cold piston/rings when parked.

Just another possibility to consider before disassembling the engine to re-do the heads again. If it's relatively fresh then I would seal any possible exhaust leaks between the header (have it decked) and the head and running it a bit longer. Consider using a sealant on the exhaust gaskets of your choice.

[lindy 911]

I don't buy it; oil would have to run uphill to leak into the exhaust port and then past the gasket as you suggest. Then it would have to migrate uphill and against the air of the fan to cover the cylinders as shown. Maybe another guess?

[Lapkritis]

I'm not sure my explanation is drawing a clear enough picture.

Oil is leaking inside the engine into the combustion chamber. I suspect it is leaking past the rings. When the engine is started, the engine is ejecting this oil out of the combustion chamber into the exhaust port. A leak exists between the head and the exhaust manifold flange. The oil then clinging to the walls of the exhaust port in the head is forced out with the flow of exhaust gases until it reaches this small leak between the head and exhaust manifold. The exhaust gases escaping through this small leak draw the oil out onto the cylinder manifold/head and the leak appears. As the engine warms, condensation forms from hot combustion gases passing over colder engine surfaces; these water droplets (water dripping from tailpipes on all cars) travel the same path as the oil picking up carbon and soot particles from the walls of the exhaust port. These too escape and accumulate in the same area as the cold-start oil. This will produce a slurry mixture that under higher temperature will flow. Higher vehicle speed and low RPM will produce air turbulence beneath the engine. As the air from the moving vehicle passes the oil cooler, it is forced to compress between the vehicle and the ground beneath. This compression force will be what drives the oil upwards when coasting when fan output is minimal.

[lindy 911]

I understood what you were saying in your first assessment, so the picture is perfectly clear. I do not believe, however, that is the root cause of the oil leak. Looks like a through-bolt o-ring to me...

[Black_Hat]

Take the heads off as a unit with the cam housing

You have it this far apart

with that out of the way the speculation will end

please take and post photos

My buddies 965 turbo just went through this same exact looking leak and it was the head to cly with niresist rings, It took a lot of hand lapping to get it right - but is leak free now

[Lapkritis]

Hmm, could be I suppose the way it's spilling on the air deflector tin. Perhaps all 3 are leaking to some extent.

Phil - did you service your O-rings/bevel the case on this yet? Hopefully you didn't use the dow corning 55 grease!

[philip j]

There is no visual indication that the through-bolts are leaking, there also is no oil on top of the engine.
I don't remember if the DOW grease was used, you don't like that method?
Our thought is it's part oil leaking past rings and head when cold and Lapkritis' idea of manifold leaks when cold may be the other part of this.


This is a fairly high boost engine and it runs great. It's only really apart this far to replace the Elgin 330 cams with custom DR 993SS cams.