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[jamie]

It's really cold outside.

No - real reason is that I got distracted by some work I have to get done before tomorrow morning...

(Sorry)

[jamie]

OK, just went for a look. I think the drip could have been from oil which was sitting in the hex recess of the galley plug.

One thing that bothers me is the plug appears to sit deep in the hole - almost deep enough to cover the oil galley that runs from the threaded section down towards the crank.

The other thing that bothers me is the cam cover plug is also sopping wet with oil. In fact the whole thing is covered in oil to the point where it's impossible to determine the source of the leak...

[jamie]

OK, I think I've got to the bottom of this. And if I'm right, it's not good.

This is the area where the flywheel rotates on the end of the crank...



The oil is originating from somewhere in here, and exiting the bottom of the bellhousing. The leak isn't from the gland nut that holds the flywheel on, as the clutch remains dry. The rear of the flywheel is dripping wet, so there must be something spraying onto it from this part of the case.

At first I assumed the leak was at the crank main seal. I fitted a new one, ran the engine again, and it did not solve the problem.

So I started looking for other obvious places. Bear in mind that the engine did not leak (in this area) before it was rebuilt. The only thing that has changed in that time is the cam cover, which appears tight, and the oil galley cover, which has been removed (to clean the galley during rebuild), the hole tapped to 3/8" NPT (tapered thread) and a brass plug installed. I was suspicious about the brass plug.

So I removed it and looked down the galley. Halfway down the threaded section there is another hole, where oil makes a 90-degree turn down towards the forwardmost main bearing.





I counted the number of threads on the brass plug that was installed - ten in total. Then I counted the number of threads from the outside of the galley down to the hole - seven. When the blass plug is tight in the crankcase, there are three threads showing buried, meaning that the end of the plug is 13 threads deep in the galley. The end of the brass plug therefore covers that 90-degree hole almost completely.

I filed the end of the plug and managed to get the length down to eight threads, which is the most I can do without compromising its integrity (it has an internal hex socket in it), but it's still not short enough not to cover that hole.

I am pretty certain what's happening here is either a loose plug, or a high pressure situation whereby the brass plug is restricting the oil system.



It might also explain the oil leak from the pump cover.

So, not sure what to make of all this. The only solution I can think of is an oversize NPT plug, that sits further out of the tapered tap, plus a bunch of PTFE paste to keep the oil out of the threads. Can't seem to find an oversize NPT plug anywhere, though...

But even worse, I'm wondering if I might have shagged the forwardmost main bearing by starving it of oil for the first 20 minutes of this engine's life.

All in all, what a total fecker.

[DustyM]

Sounds like you are onto something but I think you need to speak to someone who builds these engines regularly and get their opinion / solution.

[jamie]

Also - other thoughts include the crankcase expanding at a different rate to the brass plug...

[murph2309]

Hi Jamie - sounds like you might have a plan here. I know this is Super-tough, keep going. It's going to be all the sweeter when it's done. But what a palaver. Don't let it sour your view of the car, I know it's been fighting you a bit recently....It will pay back in spades whatever it's taken so far.

R

[sladey]

What they say is absolutely right Jamie - you'll get this in the end. Also don't make assumptions on what damage has and hasn't been caused - these engines are incredibly tough.

I can't see what clearance you have on the outside of the hole - i.e. Can you replace the plug with a nut or will the head foul the flywheel? If you could use a nut instead then you'll be able to make it the right length without damaging it's integrity - and using a different material would be easy enough

[911hillclimber]

Get a new plug? Might be larger diameter to start with.
Get one without the hex hole which uses a different means of tightening? You have freedom to shorten it.

Aside from blanking that crank bearing off from the supply even if shorter the oil pressure in the feed gallery will essentially still be the same on the new/shorter plug.

For the plug to leak it needs a seal to work with the taper thread. A fresh plug may restore the seal capability to the case but...

I would consider an application of case half sealant when re-fitting and torqueing the plug correctly if not already done.

good to see progress and some detail.

There must be some experts on these engines in the UK who can guide you. The engine builder who races the 356 of Steve, long dreadlock hair I think he has; he is a master from what I've read.

[KS]

Jamie, we use(d) aluminium 3/8NPT pipe plugs all the time on VW cases to block oil galleries. They are available in a very shallow style, and being aluminium expand at the same rate as the case. I'm amazed the guy who built the engine used that plug... Not very confidence inspiring.

DO NOT TORQUE - there is no torque setting for a tapered thread.

Here's what you need:

http://www.ebay.co.uk/itm/3-8-NPT-Male- ... uUnrK-ovsw

[KS]

By the way, you need to use Loctite thread sealant – don't overtighten - being a tapered thread, they will keep screwing in until the case cracks. The sealant will stop the leak. Good for 90+psi cold start on my race engines...

[911hillclimber]

That's the kind of thing I meant!
Steve Wright's engine guy will know too.

[sladey]

Ah - didn't realise the hole was tapered - just thought you couldn't draw for shite

[Lightweight_911]

Jamie - you should be ale to get what you need from Think Automotive in Isleworth:

http://www.thinkauto.com/acatalog/On_li ... __249.html

[jamie]

Thanks for all this, chaps.

Right, off to buy a selection of plugs and some thread sealant. Expect an update in a month!

[Dingbat]

Hi Jamie
I would suspect your main bearing is ok as it has not been run under any load and not with the clutch depressed loading up the thrust faces, sat there just running it should survive on fairly modest oil pressure. I am glad you have found your problem and it would explain the quantity of oil involved. Could I remind you that on reassembly you would be well served to replace the flywheel bolt due to the torque setting and risk of the bolt breaking.