911 ‘87 3.2 leaking cylinder

PeterM · 07:23 AM

I have had a problem with this engine for many years. When idling, it sounded like a tractor. At higher rpm it was running smooth. I found that when measuring the temperature on the exhausts, the no 1 cylinder was running cold compared to the other 5. So a lot has been checked, but it was a broken gasket on the intake manifold. See photo.

When changing the gaskets, I found that the no 1 cylinder has a leak. Please see attached photo.

I would like to have your comments on the leak. What to do ?

k

Thank you

RedCoupe · 11-22-2019, 07:21 AM

I'm not following. Are you saying that you changed the gasket on the intake runner and it's still leaking, or are you saying that after changing the intake gasket you discovered the cylinder is losing compression elsewhere?

proporsche · proporsche's Garage

i would suggest torque the heads and see .It is also possible you have a broken cylinder head- engine case stud..
Ivan

PeterM · 11-22-2019, 07:30 AM

Quote:

Originally Posted by RedCoupe

I'm not following. Are you saying that you changed the gasket on the intake runner and it's still leaking, or are you saying that after changing the intake gasket you discovered the cylinder is losing compression elsewhere?

No when changing the gaskets on the intake manifold, I saw the leak on cylinder no 1

RedCoupe · 11-22-2019, 07:39 AM

Okay, so you're seeing signs of leaking between the cylinder and head. As suggested, I'd pop valve covers on that side and check for broken head studs. If okay try to retorque the nuts.

Solamar · 11-22-2019, 07:45 AM

I just went through this on my '85 3.2L

Bad leak down results

In my case the head studs were not broken, the lower dilvars were tight and all the upper steel head studs were snug, not tight. My #'s 1 and 4 were leaking at the top just like yours.

You could try re-torquing the head studs (if there not broken) but I'd suggest your in need of a top end.

The leak can cause contaminants between the cylinder and the head that you would ideally want to remove before re-torquing. Also, I had a bit of erosion that required a slight cut on my heads to re-seal correctly.

This is what one of the leaking cylinders looked like -

If your comfortable doing the work yourself, it's not too terribly expensive, $500 + parts for a head job, + new head studs, + gaskets and probably piston rings.

I think a shop would be $5k +++

yelcab1 · 11-22-2019, 07:45 AM

I would retorque head studs and see where it goes.

yelcab1 · 11-22-2019, 07:47 AM

I love to know where you are getting your head valve job for $500. Petersen's in the Bay Area charged $750 ... 15 years ago. It would be double that now.

Flat6pac · 11-22-2019, 08:02 AM

About 20 years ago I had #3 sucking one of the intake gasket into the head airway.
I don’t think this problem went unnoticed at Porsche because the C2 used 3 studs to locate and hold the gaskets in place
Bruce

Nick Triesch · Nick Triesch's Garage

I just had a top end because the lower intake gasket on cylinder number one sucked in causing at first a bad miss then after months, complete loss of the cylinder. But the real reason for the top end was because I had a large oil
Leak where the head on the passenger side meets the motor.

sugarwood · sugarwood's Garage

Quote:

Originally Posted by yelcab1

I love to know where you are getting your head valve job for $500. Petersen's in the Bay Area charged $750 ... 15 years ago. It would be double that now.

He said if you DIY it's $500

Solamar · 11-22-2019, 06:02 PM

Quote:

Originally Posted by yelcab1

I love to know where you are getting your head valve job for $500. Petersen's in the Bay Area charged $750 ... 15 years ago. It would be double that now.

PM sent.

wjdunham · wjdunham's Garage

Quote:

Originally Posted by sugarwood

He said if you DIY it's $500

That would mean that the only work you outsource is the machining of the head surface? I think that could be done for $500 on all six heads based on what I paid for having my cylinder mating surface machined. That means valve guides and seats DIY to get you to $500, no?

Bill

PeterM · 02-04-2021, 05:47 AM

none of the head studs are broken, so that is good news

The small oil leak between the cylinder and cylinderhead is not just on cylinder no 1, but actually there is a small leak on more cylinders

Some of you suggest that I try to re-torque the head studs. I am a little afraid of doing that, because don't you risk to break a head stud doing that ?

If I re-torque the head studs, what torque would you suggest ?

yelcab1 · 02-04-2021, 06:00 AM

Quote:

Originally Posted by PeterM

...

If I re-torque the head studs, what torque would you suggest ?

There are two schools of thoughts:

1. Loosen it and then retorque to 26 ft-lbs (or thereabout, close to the factory spec)
or
2. Set the torque wrench to 22-24 lbs, torque it until it clicks, leave it alone.

You decide.

faapgar · 02-04-2021, 06:46 AM

Easy cure that works forever.I have using these since the late 80,s.It is a repair head gasket for the 3.2 from Porsche.930-104-381-01.Material is Inconel with a light high temperature coating.I use these on 3.2-3.5 engines.They are good on Turbos up to 1.2 bar.That is the safe limit.No sweating or drips or anything other than a great seal.On larger than 3.2 the inside edge is opened up to match the bore.Here is a pic of 3.4 I put together last week.

If your heads have been resurfaced this creates the original geometry of engine width and chain angle.Gaskets are 0.50mm thick.Ciao Fred

Solamar · 07:54 AM

Quote:

Originally Posted by wjdunham

That would mean that the only work you outsource is the machining of the head surface? I think that could be done for $500 on all six heads based on what I paid for having my cylinder mating surface machined. That means valve guides and seats DIY to get you to $500, no?

Bill

Hi Bill,

From a local, highly regarded Porsche only engine builder. $90 to surface all heads and $475 for a complete valve job (disassemble, bead blast, inspect, cut seats, replace 12 valve guides) any required parts are additional.

This price was right in line with another quote I received from another highly regarded Porsche machinist.

It is shocking what some shops charge...

Solamar · 02-04-2021, 07:48 AM

Quote:

Originally Posted by PeterM

none of the head studs are broken, so that is good news

The small oil leak between the cylinder and cylinderhead is not just on cylinder no 1, but actually there is a small leak on more cylinders

Some of you suggest that I try to re-torque the head studs. I am a little afraid of doing that, because don't you risk to break a head stud doing that ?

If I re-torque the head studs, what torque would you suggest ?

I'd suggest a top-end is in your future. Re-torqueing the head studs may buy you some time. Or, snap, accelerate your top end

yelcab1 · 02-04-2021, 07:51 AM

Quote:

Originally Posted by Solamar

Hi Bill,

From a local, highly regarded Porsche only engine builder. $90 to surface all heads and $475 for a complete valve job (disassemble, bead blast, inspect, cut seats, replace 12 valve guides) any required parts are additional.

This price was right in line with another quote a received from another highly regarded Porsche machinist.

It is shocking what some shops charge...

Share the name of the shop.

Solamar · 02-04-2021, 08:19 AM

Quote:

Originally Posted by yelcab1

Share the name of the shop.

Neither of these shops publish their prices online, so it doesn't seem my place to do it for them.

I'll gladly share the info via PM (yelcab I PM'd you last year).

Ollie's publishes their price list -

http://www.olliesmachine.com/uploads/ollies_price_list_March_2019.pdf

$420 for a three angle valve job
$15 per valve guide