Cylinder leaking on just rebuilt 2.7
 

Folks,
Some time back, I purchased a newly rebuilt '74 2.7S engine. After some delay in getting it into the car and running properly (converted from CIS to ITBs and MS3), I had to pull the engine again to address a problem with the alternator (its in a 914-6).

As I was pulling the heat exchangers off the engine, I noticed oil on the underside that had run down from the top. Once fully removed, I could see that the oil is coming from the #2 cylinder in between the barrel and the head.
http://forums.pelicanparts.com/uploa...1535170578.jpg

The engine has about 175 miles on it. I understand that at about 500 miles, I need to have the heads re-torgued (or do it myself).

With the engine out of the car presently, is this leak something that re-torquing the heads will eliminate?

911 heads do not need to be re-torqued (unless one uses the wrong head studs).

I would find out what studs you have and whether the heads were resurfaced when the valve job was done.

I have always been warned to check the head stud torque after break in.

Was I given out dated info?

.

Don't be convinced its coming from the barrel unless clearly seems wet,or check to see its not coming from the top of the motor,chased 7 leaks on my 914/6 conversion most didn't come from where I thought and all fixed except for turbo valve covers to fit yet.
Good luck.

That practice is something that migrated from doing other water-cooled engines; domestic & foreign. :)

There are MANY others, too. :) :)

I've pulled the fan/alternator and had a look at the top side of the engine. All dry there. I can find no other leak other that at the bottom of cyl. #2 and it certainly looks like its between the barrel and the head.

Is there any thing else I should check?

http://forums.pelicanparts.com/uploa...1535332469.jpg

If re-torquing the studs is not a potential fix, what's next?

Please inform us which studs are to be avoided for the various 911 engines in your experience. Thanks !

If studs do loosen on their own, I suppose they should be regularly checked, not just after break in, otherwise I don't understand why the break in process is special as far as the studs are concerned.

I had been told from an experienced 911 engine builder it was very important to check the torque after break in.

Wayne in his book states this as well.

After my recent rebuild of an SC motor I checked the head stud torque after about 500 miles and all the studs needed to be tightened. Most took almost 45* to get back up to torque. I had used VR base gaskets.

Later on I had to disassemble this motor. This time I used OE base gaskets upon re-assembly. This time around when I checked all the studs were still tight.

YMMV

You have nothing to lose by trying to tighten the head nuts. Maybe it will stop the leak.

-Andy

Source of leak found!
 

Now, what do I do to fix it?!

I removed the lower valve cover on the 1-3 bank and found that the source of the leak seems to be coming from the allen nut on the end of the exhaust rocker shaft of the #1 cyl. The oil is leaking there, wetting the cam tower nut below it, and then running back towards the head and leaking out between the cam tower and the head. At least that's what it looks like to me.

http://forums.pelicanparts.com/uploa...1535760324.jpg
http://forums.pelicanparts.com/uploa...1535760324.jpg
http://forums.pelicanparts.com/uploa...1535760324.jpg

Do you concur?

What's the best method to address the leak?

It certainly looks like you found it. There’s a range of area in the bore that the rocker shaft can use to seal. You can loosen the bolt and push the rocker shaft 1 or 2mm then retighten it. You can also try the RSR rocker shaft seals. As a last resort you could remove, clean and reinstall with a sealant. These shafts can require a lot of torque sometimes to seal and not “walk” out of the bore.

-Andy

I wasn't able to loosen and install a new seal so I carefully applied a little of the Hondabond H4 on each side the the rocker arm and that did the trick.