Clyinder/Piston Kits... Which one?

[daring]

I am looking at the possibility of having to fix that irritating (Well OK, downright @#%!%!, but I'll keep it family friendly) oil leak that those of us with early 964's fear could happen at any time.

I am shopping around for the Cylinder / Piston kit that Porsche recommended when correcting the seal problem on the heads. At the AllDataDIY website I get 4 seperate part numbers on the TSB (#9404). They are as follows:

964 103 915 22
964 103 915 23
964 103 915 24
964 103 915 25

Are these just successive part numbers that supercede the previous OR are they different sizes (i.e. Bore, Height, etc.). If the latter, Which is the one I need?

Your help is appreciated.

Thanks,

Darin
'90 C2 Cab.

[maxnine11]

i can only partially answer your question. I believe that the different last two digits in the above part numbers refer to the piston weights and markings ( ++/+ or -/-- etc.)
max

[surflvr911sc]

Is it leaking or are you looking at preventive maintenance? If it’s not leaking yet then don’t worry about it until it does and it probably won’t at this point.

If it is leaking, well OK, but does anyone know if Porsche still warranties this problem. My guess would be no but it might be worth checking into.

[Bill Verburg]

Max is correct,

22 - 644-652g mark --/-
23 - 652-660g mark +/++
24 - 644 -652g mark --/-
25 - 652-660g mark +/++

They are all listed as 91-

if you buy a set they should all belong to the same weight and height group. If buying individually then you need the marks to determine what's needed.

For the price of a set of those a set of 102mm slip fits isn't that much more.

There are 2 different leaks in those engines, at the the head gasket and at the cylinder base. You will also need to have the grooves machined into the case wall to properly seal at the base

[daring]

Thanks all for such quick replies...

Surf... It is leaking. The kind of leak that leaves a pretty heavy mist on the back of the car just after putting 30 miles on a fresh wash. So much so that it has a pretty constant drip off of the crankcase right after turning it off (Granted I am running 0-40w Mobil 1 in August in So. Cal.). At $5.00 a bottle I will be able to pay for a new engine soon!!!! Porsche would have put a time limit on the warranty and 13 years is probably way off, at my best guess.

Max & Bill... Thanks for the breakdown. Bill you note that they are listed as 91-... Do you know the part numbers for a 90? Either way, Does it matter which set I get? and How do I tell? Those part numbers come as a complete set so I would get all 6 pistons/cyl. etc. for the price.

In my case, Bill, I have 3 leaks (1 is easy to fix).... Cyl. 1 & 3 are leaking at the base to crankcase and 2 is leaking at the head to cyl. and then I have the valve cover gasket leaking on the back of three by the knock sensor. How do I know this you may ask?For the record, I have washed the engine, parked it and jacked it up. I can re-clean it off every couple of hours and then see droplets forming at the various spots mentioned. It's a real heartbreaker!!! You mentioned the 102mm set was similar in price. For the record I can pick up the part that ends with #25 today for $2,072. How does that compare?

Bill, the way I read everything I have ever seen on this subject, is that the base of the Cyl. has to be machined for the grove, not the case. I would assume that if you machine both pieces you would need a real large 'O' ring to fill this space.

The real pisser about all of this is that this car had a valve job 26,000 miles ago!! Now that I have a much better understanding of how these engines are constructed, I can tell from the invoice that cylinder updates were not paid for. The previous owner probably didn't know about this issue and his regular garage doesn't appear to specialize in these cars. They probably put the car back together just like they took it apart without ever accounting for any changes that Porsche made along the way(except for new valves and a re-facing). On top of that, he paid $5,000 for the job. Well, I guess I am into this car for the next 10 years. Might as well make the best of it!!!

Darin

[Bill Verburg]

The cyl is machined and the RSs also used a machined groove in the case. I have personal experience on my RS w/ the failure of the seals w/ only the cyl. groove. You need to replace all 6 p/c as a set, I would get the lightest ones. You will also want to have the heads resurfaced to seal properly w/ the new headgaskets.

You need to update all of the cyl to the later design w/ headgaskets.

I believe that Wayne had the 102s for mid $2k a while ago check around.

[daring]

Bill,

Thanks for all of the info. I will make sure that I get the case and cyl. done properly this time around. I know I have to pay a truck load to get it done, so I'll do my best to make sure that it's a REAL long time before I have to do something like this again.

Darin