Alex Sol

I've searched high and low both in and out of this site and find this issue very confusing.

I have a 1991 964 with cylinder that has groove for metal ring / head gasket.

When installed the metal ring becomes flat and acts as a gasket.

Speaking to several local porshe specialists, i under stand that somewhere along the way two things happened:

1. the 89,90 and 91 964s came from the factory with no groove for gaskets. If the motor leaked significantly while under warrantee the factory would 'fix' the issue by either replacing the piston/cylinder with 'updated' groove for gaskets.

2. some time in 1991, the factory decided to groove all cylinders and use the metal seal ring as a gasket

so here's my question, why is it that three different authorities on porsche 911 rebuilding telling me that the piston / cylinder combo currently comes with no grooves for gasket and rely on metal to metal contact?

so confused!!

UncleRemus

Technically, the groove is for a flame ring not a gasket. Maybe they are saying gasket as in a traditional gasket.

crg53

I don't know who your 3 Porsche authorities are, but if you are referring to the 3.6 air cooled engines, they are wrong. Late in MY 1991 engines with serial number 62M06836, M64.01 and later, all had the head gasket upgrade and that carried on right up to 1998 when they went to water cooled engines.
FYI my car is a 1991 build date Dec 14th 1990, and the engine has the head gasket upgrade.

UncleRemus

I'll have you know that I had a very vivid nightmare that I was holding one of my 1993 3.6 heads in my hand thinking . . . he RIGHT! No groove for a gasket!

Alex Sol

okay crg53. . that makes sense.

and to confirm that the groove for the 'flame ring' or 'seal ring' or what i'm calling a 'head gasket' is in the cylinder and not the head right???

i have the 1991 964 3.6 - i'll check the serial number

crg53

Your are correct, the groove is in the cylinder.
I should add to this, if your car is equipped with Tiptronic transmission M64.02, the engine serial number is 62M52757 and later for having the factory head gasket upgrade.

Alex Sol

got it! i have the 5 speed...

Alex Sol

so uncle remus. does your 1993 cylinders have the groove for the ring? or was that the nightmare??

strange dream. it must have em....

Aurelian Fousse

Anyone have an official source on when the engines started gettinf gasket, like a starting engine serial number? In process of buying a 1991 praying to Saint Ferry that it has gaskets on!

UPDATE: found it, for anyone who is interested: http://www.pcarworkshop.com/images/4...0494geolab.pdf

Johns Pcar

Answer is also in this thread above, but starting engine numbers to receive head gaskets is 62M06836.

This started late November 1990. I have a build date of 12-10-90 and have the head gaskets.

Aurelian Fousse

Yeah I know, just needed some official document to make sure before buying my 91 964, could also be useful if and when I resell it some day

John McM

It will have some impact on future resale value but not as much as in the past. You should always buy on condition and head gaskets or not pale into insignificance with all of the other problems a 964 engine could have.