Just installed engine...now it leaks!!!

[island911]

From "Fact or Fiction :Oil drippings from your motor. "
Originally posted by Wayne at Pelican Parts
It's common for 911 engines to leak oil. However, the engine *should not* leak oil under normal circumstances.

One true test of a quality rebuild is if it leaks oil or not.

-Wayne

I believe this to be true. I've seen too many dry 911 motors, including my own 22 year old factory built engine.

I find it amazing that with the age of the seals and gaskets more aren't leaking.

Also -- When I was 911 shopping, whenever I heard the defensive words of "they ALL leak" . . . I took that as the seller saying; "I want to pawn off a car full of neglected details."
YMMV

[snowman]

ITs what you have to do so it dosen't leak and sometimes the plain gasket, installed as it was ment to be needs some extra help. Mine does not leak now, but theres RTV on those gaskets, and the valve cover gaskets are the $50 aircraft ones, NOT the original by any means. By the way the only place I did not use RTV besides the valve covers was the o rings on the case bolts. No leaks there on any of the 3 times I rebuilt this thing.

PS I used Vitran o rings, the same size, but from a local supplier. Much better than whatever came in the original german Victor Reinz stuff.

[Wayne 962]

Let's settle the air here, and agree on this statement?

"911 Engine are more prone to leaking than other water cooled engines because of their increased total expansion when warm."

-Wayne

[speeder]

Snowman, Could you run down for me all of the places where you used RTV silicone on your motor?

[snowman]

RTV used on following:
1. Round oil pan cover on bottom of engine
2. Both front and bottom chain cover gaskets
3. breather cover on top of engine
4. on outside of two rocker arm shafts, that looked suspect, ie had some damage to shaft bores. This is in addition to using rocker sealing rings from Andial. Note: this will make removing these two rocker arms a very painful experience.

Pre-formed, aircraft grade, silicone valve cover gaskets.

[Wayne 962]

1-3 is okay in my opinion - as long as it's not gooped on. I would personally use something lighter like Curil-T, rather than silicone.

If you have trouble with cam towers that are so scored, they won't hold even with the RSR seals, I would suggest getting new ones...

-Wayne

[snowman]

Wayne, don't you sell the silicone valve cover gaskets?

[ChrisBennet]

Originally posted by snowman
RTV used on following:
1. Round oil pan cover on bottom of engine
2. Both front and bottom chain cover gaskets
3. breather cover on top of engine
4. on outside of two rocker arm shafts, that looked suspect, ie had some damage to shaft bores. This is in addition to using rocker sealing rings from Andial. Note: this will make removing these two rocker arms a very painful experience.

Pre-formed, aircraft grade, silicone valve cover gaskets.

A mechanic friend of mine uses RTV in the #4 case. I suspect his customers would rather have the leak go away for an hours labor than pay to have their cam towers replaced.

I'm not a fan of RTV but lets be realistic here, not everyone wants to have every engine mating surfaces lapped and trued to fix leaks. Some RTV used judiciously is a solution even if it isn't the Right Way.

-Chris

[john walker's workshop]

ever seen RTV goobered on a cam tower to stop a leak? it's generally wet with oil. basically very poor sealing ability when just goobered on, and looks very un-professional.

[ChrisBennet]

Originally posted by john walker's workshop
ever seen RTV goobered on a cam tower to stop a leak? it's generally wet with oil. basically very poor sealing ability when just goobered on, and looks very un-professional.

My friend uses it in the ends of the rocker shaft, in the hole.
I've worked on a few "leakers" that people had tried to stop leaking by slobberying RTV in various locations. You're right, it didn't stop the leaks.
-Chris

[Wayne 962]

I have an engine with a cam tower leak (actually both sides). I was thinking some type of Dow Corning sealant injected with a syringe. Either that or remove the engine. Any thoughts JW?

-Wayne

[john walker's workshop]

heads to cam towers, i would disassemble and reseal. generally hard to tell exactly where they're leaking, and topical ointments don't usually work, (and look "backyard"). rocker shaft leaks, are anything from tightening them more, add "o" rings, or replace the towers if the shaft bores are toast, as you know.

[snowman]

Once there is oil on the surfaces your are sorta out of luck. Its really really hard and may be impossible to remove all the oil without taking it apart and putting it in the hot tank. Thats why I chose the pre emtive strike ( actually the 3 rd teardown for oil leaks).

Note I did not actually put RTV on the round part of the rocker shaft. I first assembled the rockers, just like normal, then I ran a complete bead of RTVaround the on outside of the shaft, sort or plugged the hole,so to speak. If there is oil there I do not think the RTV will stick well enough to seal. IT is a last ditch effort and better than scapping the cam tower, at least in my opinion. By the way the shafts were not damaged seriously, just small lateral grooves in a couple of bores, the kind of groove that can leak but otherwise is immaterial. No scoring or damage like that.

[speeder]

How do rocker shaft bores get to be toast in the cam towers when it is not a moving part? (The shaft+cam tower). Just from the spreading force of the expanding shaft? Just curious.

[Doug Zielke]

Originally posted by speeder
How do rocker shaft bores get to be toast in the cam towers when it is not a moving part? (The shaft+cam tower). Just from the spreading force of the expanding shaft? Just curious.

Denis,
If a PO/M *forced* them out (the expansion bolt not fully unscrewed), the bore will be galled/scored and prone to leak.

[john walker's workshop]

also, if they have been run loose, or if one slipped out and the engine was run for a while with it just hanging on one side, the bore, even though still smooth looking, can be too large for the shaft to expand and get a proper grip, or ovaled, so it would leak.

[WERK I]

Update:
The engine is still leaking oil out the spigot bores(left bank) after five minutes of running. There is one bit of information that I forgot to mention before. The engine is using early C2 turbo pistons and cylinders. On disassembly, the engine had the copper base gaskets and was not leaking there before. The only work done on the case was removal of the devlar studs and replacement with factory steel studs. Deck height on all the cylinders is the same according to the factory markings. The right bank is not leaking, but is damp to the touch. It almost looks like a "wick effect". This is really getting to me!! I am a pro at engine removal and tear down, but this is not what I want to put on my resume! ;-)
John Walker, have you seen anything like this before?
Thanks everyone for your invaluable assistance.

[911pcars]

"Deck height on all the cylinders is the same according to the factory markings."

I believe that would be the cylinder height marks on the cylinders, not deck height. They have to be the same, otherwise the clamping force is different on each cylinder.

FWIW, if you don't check, you'll never know. What takes more time, R&Ring the drivetrain/taking off the top end or checking cylinder height? You should never leave anything to chance, if at all possible.

Sherwood

[ChrisBennet]

Dave,
Do you suppose there might be a nick/bump in the seating surface someplace?
When I assemble a motor, I bolt the heads on individually using the camcarrier as a holding fixture to make sure everything lines up. I torque the heads down and pull off the cam carrier. Then I put a straight edge across the tops of the heads to check that the heights are even.
On the bright side, you are probably learning stuff that you wouldn't if everything had gone together smoothly.
-Chris

[WERK I]

Sherwood,
Let's use some logic here.
1.) The spigot bores were not leaking before. The case was split to install new rod bearings and mains and to reseal for a minor case leak.
2.) The leak is consistent across the banks. 1-3 leak and 4-6 are damp. This is not a symptom of cylinder height(thanks for the correction) mismatch, but something else.