seanpower

Thank you for all of the thoughts, I have been absorbed in end of the year work and am now finally able to refocus on this. I have attached two photos of the leak. By way of update, I now believe the oil is coming from inside the case so hopefully looking at a failed base gasket only. I haven't had to add any oil in the last 1000 miles. I am hopeful that it is not a head stud, and am just happy to get started on the repair. They are dropping the motor this week to take a closer look.

As a general proposition, does the group believe that well done mods devalue the car? If it is "only" a gasket, I am considering about doing the exhaust and ECU tuning. (My S4 spoiled my on low end TQ).

garrett376

I'll bet you have leaking through-bolt o-rings... that's quite common, and looks like what you show. Good luck, and keep us posted!

Richard Curtis

Garrett376: Can leaking through-bolt O-rings be replaced without removing the engine?

garrett376

Hi Richard - unfortunately I think there are only two through bolts that can be removed without removing the cylinders, so the answer is usually, and unfortunately, no! Too bad because the replacement o-rings are really cheap, and as long as the washers aren't corroded to the case (like they were on one of my engines) they're really easy to replace, and can be done without even splitting the case if desired.

In the pics below you can see I had to grind the crap out of them to get out the washers, to replace the o-rings below... buggers! You can also see how the cylinder mating surface eclipses the bolts, which is why you can't remove the through-bolts without removing the cylinders.

C24FUN

seanpower,

It may not be as bad as it looks. A few years ago the underside of my '90 C2 was identical to yours so I knew it had to be looked at. That's about the only part of your mechanics advice that isn't in question: the engine has to come out of the car to find out where the leaks are.

My advice would be to take it to a pressure wash or steam clean service and have as much hot soapy water sprayed on it as possible from above and below to clean off most of the existing oil, drive it for a bit to dry it and get a bit more oil coming out of the leaky spots then get the engine out. You or your mechanic should now be able to spot the problem areas.

When I did this I found that the major culprits were as others have indicated, the oil pressure sender, the case through bolts and the oil line from the oil filter to the base of the engine (the one with the 10 inches of flex line in the middle of it that runs along the rear of the engine). By just addressing these issues I could have had a near dry engine for less than $2000.

For reasons mostly related to my engineering background and a compulsion to seek perfection I ended up having a very good and local mechanic do a complete top end rebuild. I saved some money by pulling the engine myself and sourcing parts including near new pistons, cylinders, heads and cams. Still, with all new valves and replacing any worn part, this cost me under $7k US (60/40 parts/labour) which is in the mid-range of your estimates. The engine is now bone dry and will probably run another 75,000 miles without major work).

Anyway you won't know what's up until you have a look at it, but make sure the person looking is someone you trust, otherwise it can get un-necessarily expensive.

As far as what else to do when it's out: for sure check the clutch; clean and paint the engine tin; check the inside of your valve covers to see if the factory coating is flaking and clean/repaint if necessary; a primary muffler bypass pipe improves power slightly and exhaust note amazingly; many other things that are mostly cosmetic....

Good luck!

Jim G.

Qweevox

Wow…with some of the price quotes on the cost of a rebuild it’s no wonder 964 owners should be fairly handy. One of the previous posters wrote that his mechanic quoted him $18,000 for an engine rebuild!

The 964 has a reputation for leaking oil, it seems to me pulling the engine and resealing the thing is the best bet once a leak starts. It’d give the owner time to upgrade a few things all at once. Which VIN numbers are the best to look for in the 964. I read that the model year might tell the whole story. I know Porsche made several modifications in the engine over the years to fix some of the issues. I guess the best year would have to be 93’s, but is there a VIN number list somewhere that can let a potential buyer know what to expect?

jimq

There arent many aircooled Porsches that dont leak oil sooner or later. 964's arent any worse then the rest of them overall.

seanpower

Regarding the leak, as an update, it looks like things are not as bad as they could have been. The leak is coming from the base gasket of cylinder 1 and 2, and the case through bolts on 1 and 2 and possibly 3 (Garrett was right on). So am going ahead and doing the top end rebuild - and might have it back on the road as early as next Friday, which is fantastic news. Because the clutch was showing considerable wear and had not yet been replaced (67,000 miles, but C4), I am doing that as well (piggy-backing on the existing labor). I am also reconditioning the heads by resurfacing, changing guides, etc, as they are somewhat worn.

All told, I should be able to get out for "only" around $6,000, and have an engine that will likely go another 75,000 miles without any major issues. I cannot wait to get it rolling again. Thanks for the therapy throughout this process. Below are some photos of the WIP.

stevepaa

oops

Slow RSA

Let me know if you go the 993 route, I am looking for a rough 964 motor

Slow RSA

Sorry, didn't see the second page, good luck getting humpty put back together!

dhc905

Question for my potential purchase (nothing says I need this, but just spoke to a local porsche mechanic and he said 10K for a rebuild if necessary; and he can only really tell if I do a $600 PPI):

If the base cylinder O rings are leaking, do I need a specialized porsche guy doing it, or is it more a function of having the right tools? I.e. can have my mechanic who works on my later model BMW's (2000+) do a base cylinder o ring replacement, assuming that's what the problem is?

Also what's the story with a valve guide adjustment? Do at the same time? Need a specialist for that?

Thx!

STUARTQ

I only paid $400 for very detailed PPI in Houston. It included a comp and leak down test and loads of photos.
In Grands Rapids, the cost was $250 excluding the comp and leak down.
Finally a PPI in the UK was £360 again that did not include a comp and leak test.
$600 sounds expensive for the states.

dhc905

How long ago was that? The mechanic said "we start at $350 for a porsche (btw, the dealership charges $350, so I'm not sure what they're thinking; a shop closer to me [but farther from the seller] charges 175). If you want a leak down it's $600 and we highly recommend that because if you need a rebuild it's 10K".

So that got me thinking - at 6% of total anticipated worst-case cost, I'd almost rather skip that part and drive until I know for a fact that it needs a rebuild and go from there. Rather than paying 600 for someone to tell me that at some point I need a rebuild, because it seems ineviatable that that will be the case.

Speaking of which, at what point do you guys go in for the rebuild? When the engine is spewing oil? Dime sized drips? Besides oil leaking, what indications suggest a rebuild is imminent?

STUARTQ

This was April last year.
1st one was in Houston, the 2nd in Grand Rapids.