Cylinder/Head leaks - Need your opinion

[deftom]

Hi Everyone,

I have a Porsche 911 2.7 165 CV From 1977.

I bought it 10 years ago.
7 years ago, I blew up the engine (ring failure -> too much ware) so I rebuild it.
I installed Helicoil with 993 head stud.
I also know that this is not what is recommanded for this engine.
What is done is done, I didn't have to proper knowlegde at the time.

I did around 10 000 miles since.

Yesterday, I did a checkup on the engine and I discover this.


The image is not so clear.

So it's on the cylinder 3 and you are seeing the head/cylinder.

I checked the head stud, and they are in place.

I would have some opinion regarding what to do.

Thanks a lot.

Regards;

Thomas

[deftom]

[Alan L]

Cheapest option is to check the torque on the head studs.
Alan

[deftom]

You mean unscrew and rescrew or just check the torque?

Thank you

[Alan L]

Don't unscrew. You are looking for a (hopefully) loose one - or two.
Just set the torque wrench to spec and crank. If you get to that torque and nothing moves, try the next one. Do not go beyond spec.
Alan

[deftom]

Ok thanks, I will have to hold my breath during the process

[deftom]

Ok, So I checked the torque on each bolt, And it didn't move that much before I got to the spec.
So good news, threads are not pulling out.
But in the other hand, I don't know what is causing that...
DOes anyone has an idea.

By the way: head were resurfaced and head gasket where brand new

[Trackrash]

Have you done a compression test or a leakdown test? Do you hear a noise when the motor is running that sounds like leaking compression?

[deftom]

Nothing particular.

But once I will receive the cover valve gasket, I will double check that

[safe]

Whats the actual problem?

[deftom]

It seems that there is a leak between cylinder and head junction. I did see those trace of oil 3000 km before.

[safe]

If you don't notice any exhaust leak while running its probably just a little seepage during cool down.
But check compression and leak down.

[deftom]

Ok thanks

[Neil Harvey]

Originally Posted by deftom

It seems that there is a leak between cylinder and head junction. I did see those trace of oil 3000 km before.

What you are seeing is very typical. The Exhaust side of the chamber is the hottest and expands the most. We see leakage between the Head and Cylinder there, all the time.

We addressed this years ago and do the sealing mod for many to this day. This is not the stainless ring done by some others. That technology was never to seal the cylinder but stop the torching of head and cylinder in older Turbo engines when the fueling was stopped on decel but the Ignition continued.

The picture is of a 500 + HP 930 engine with over 25 years service on disassembly.

[Neil Harvey]

Other photo is after Heads rebuilt.

[john walker's workshop]

So what is the sealing mod?

[deftom]

I did not seal on my motor. I just put the cylinder/head gasket

[john walker's workshop]

I was referring to the above copper looking rings.