Policies
and Warranty Statement
What's the deal on 964 Head Leakage? Is it important?
Here is a picture of a 964 with leaky head to cylinder mating surface: (Click to zoom)
and here's how porsche fixed it:
First - a little history. All 911 SCs had these "Ring" head gaskets. it was basically a hollow or spring filled "C" section that inserted into the groove on the cylinder at the head mating surface. The cylinders looked With the 3.2 Carrera, for some unknown reason.
Here's a picture of the SC setup:
You can see that the cylinder is similar to the 964 with the a grove cut in it. Notice that a narrow (6mm or so with the gasket groove) ring sticks up from the cylinder. This fits into a machined ring in the head to locate the cylinder to the head. You can see from the high performance 3.2 below that no such groove exists
So the Carreras seemed to be OK and porsche said let's go with that so they made the 3.6s from 1989 through mid 1991 in this manner with no head gasket. Sometime in there, however they started to leak. Now the flat area on the 3.6 is fairly narrow and they didn't want to machine in a groove so they redesigned the entire cylinder to have a wide flat area, and they machined a much larger locating area the head to accommodate it.
.
(The above are from a 993 Varioram)
One of two things happened to the early engines:
1) They leaked, but not enough to be a problem (even the engine
shown above wasn't leaking to porsches definition, wet to the touch)
and
they are still leaking. This is really not a problem in general
because
they only tend to leak when they are cold and realize that this is
combustion
product and/or a very small amount of oil leakage.
2) Porsche fixed them under warranty, or they have been subsequently rebuilt.
What does it take to fix the problem?
1) Buy new P&Cs. About $2400 or so, maybe as low as
$1000
for a nice used set. 993 P&Cs wont work because the small end
of the rod is narrower.
2) Do a top end (you'll have the heads to have them machined, so
a valve job is in order, about 25 hours labor and $1000 in parts)
3) Have the heads machined by someone who knows what they are
doing.
We charge $400 for the machine work.
The bright side is that after spending the $4-5K for a top end you'll have a nice motor.