r-mm

I'm having a 964 with approx 130k looked at as we speak. In the car's history the engine has not been opened to my knowledge. Wondering what acceptable leak down and compression numbers would be? For me, this car will be a lite duty stock daily driver (~5000/year).

Car has some 'typical' oil leaks @ base of cylinders, chain covers and elsewhere. Not massive spills but drippers for sure. Wondering how many of you live and let live with things like this?

I'm not trying to blind myself to a needy car - just get a feeling for how agressive to be in negotiation.

Steve Weiner-Rennsport Systems

Hi,

Oil leaks, especially on 964's that have not been touched, are not unusual at all. Its all due to the degradation of seals, gaskets & O-rings due to heat.

I like to see leakdowns in the 2-6% range. When I see numbers over 8%, I listen closely for the source: intake valves, exhaust valves and pistons/rings. Anything over 12% is cause for concern if the leakage is coming from the oil tank filler since thats a ring and/or piston issue.

IMHO at 130K, they ALL need a valve job due to guide and exhaust valve stem wear.

Its not a deal killer for a good car,...

r-mm

Thanks for the reply.

I have leakdown numbers from the most accessible cylinder: 9%.
I realize that there is not a litmus test to say when a number is okay or not, but is it fair to say given the millage that if the others come in at this range, I need to budget for at minimum a top end rebuild & reseal? Maybe not immediately (car drove very nicely) but it would seem that valve guide wear is a self fulfilling prophecy and worn guide could lead to something worse like a snapped valve?

The shop performing the PPI was understandably reluctant to quote a top end rebuild on a motor before opening it but I ended up getting $7000 presuming no bottom end work and no new pistons. Sound right?

Steve Weiner-Rennsport Systems

I hope you have leakdown values from ALL 6 cylinders,..........

Worn guides result in excessive oil consumption and in the worst scenario, valve failure due to insufficient cooling. High oil consumption leaves heavy deposits on the valves, combustion chambers, piston crowns and rings. Further, these deposits create ignition sources for detonation & pre-ignition, both of which are not good at all.

One determines guide wear either by oil consumption or by measuring side play in the valve assembly. If the engine uses 1 qt/800 miles, its time for a valve job.

Labor rates and parts requirements do vary so I cannot tell you if that $7K is accurate or not.

r-mm

I now have the values from all cylinders and they are
9%
18%
27%
30%
23%
19%
10%

Leakage was reported at the rings exhaust valves.

The shop gave me a pretty good walk thru of the costs associated with a full top end rebuild. The wild card seems to be whether pistons and cylinders are needed - I was surprised to see a they retail for $3.5k + (pelican parts). Can you comment on how often you see the need to replace these? I realize I'm asking unanswerable questions here but I'm looking to shape my expectations.

pcarhiway

As has been mentioned in the past ---- Run, Forrest ...... Run !!!!!!!

r-mm

Not sure I understand this sentiment. The car presents and drives impressively. I'm fairly certain the owner did not anticipate these results and may very well be open to negotiating to remove the price of the top end engine rebuild ($7k is the number I used) from the asking price. The risk I'm assuming is that more than the top end needs seeing to. What I'm asking here is how common piston and cylinder damage is.

If you were offered a car with 130k miles and an unrebuilt yet passable engine for X or the same car with motor problems for X-rebuild costs, which would you take?

I realize the mantra is buy the best you can afford but honestly, even if I factored for a $15k full rebuild, this car might still be cheaper than what some people are asking for 80-100k mile cars with no rebuild.

I'm happy to walk if the owner balks at a discount but I'm not scared because the car needs work. Am I wrong?

Crazylekiwi

It is just a car. It has issues which are entirely normal at its milage. The issues have been identified and the cost to remedy has been ballpark quoted. This is an enviable position to be in to start the negotiation. If it was me, I'd be very aggressive in the negotiation as the owner may very well be shocked at the cylinder values and look to exit the car quickly.

Steve Weiner-Rennsport Systems

I'd guess that you may need new P/C's, based on the evidence above and my experience with these. Ring leakage is usually due to worn piston ring lands as well rings so these would need a detailed inspection before determining whether to replace them or not.

I would be prepared for a $12K job and if its less, you will get pleasantly surprised which is always a good thing.

Pistons and cylinders get damaged from dirt and less-than-ideal maintenance practices. Using a K&N air filter is one example of this and poor oil change intervals would be the other.

carioca

I think you are right on your approach and doing your due diligence as suggested here in the forums on many occasions. It might be even better to you if you are a DIY type of guy and is confident in tackling some of the work required. As mentioned by Crazylekiwi you are in a very good negotiating position.

fbfisher

While you are asking the right questions, It sounds like you really want THIS car. If so, I'd take Steve's $12k number for engine work to the seller, and obligate yourself to refund the difference if the bill comes in for less.

pcarhiway

New parts (in addition to various bolts, nuts, gaskets, etc.) summary (in broad brushstrokes):

1. main bearings
2. rod bearings
3. intermediate shaft and gears
4. intermediate bearings
5. timing chains
6. cam gears
7. chain rails
8. tensioners
9. tensioner rails
10. lifters
11. valves
12. valve guides
13. rings
14. all service parts (spark plugs, belts, rotors, caps, filters, etc.)
15. complete valve/head/cam tower work by German Precision

Grand total (including labor (for, among other things, engine removal, disassembly, inspection, reassembly and reinstallation): about $17k.





Would you not have to be able to purchase the 130,000 mile 964 for a very low initial purchase price to make the valuation work out in your favor, and the engine rebuild may not be all that the car needs ....

Then once the work is done and the money spent, how much is the car worth at that point?

Just be very wary about thinking $12,000 will get the car where you want to have it.

Just sayin ....

jack.pe

Hi,

I had my car PPI'd as well when i got it and my leak down values were slightly better than yours but not a million miles off. I was advised at the time and also by another shop which has previously worked on the car that the figures themselves vary enormously depending on how they are carried out and that unless you intend to track a lot or race, figures like this are not necessarily a guarantee you need to go for a rebuild. My car was leaking a little but a main service and a change of valve and other gaskets seems to have sorted it. The verdict from the two specialist garages has been the same, yes the car might be putting out a little less power than stock, but unless it starts smoking a lot or running badly it does not necessary need a rebuild. They both drove it a said that the power is good and that there is no current need for a rebuild.
I am no expert and am not saying your car is fine as it is, but just that i have been told that often a drive in the car by someone who knows what they are doing is more telling than leak down figures.
Also been told that these engines are very strong and do not just go BANG like the later ones, you should get plenty or warning in the way it drives if it is coming up for a rebuild..

I'm obviously tempting fate here and hope my car does not prove me wrong!

r-mm

Boy is this a difficult one.

Agree that the car can probably be driven the 5,000 miles a year I'll drive it for a long time. The fear would be dropping a valve but if the engine needs P+C anyway...

This thread and a night of research also leads me to agree that $12k would be a good budget number should P+C be required.

I started by asking for a $10k discount. This was a non-starter as it put the purchase price into the mid 4 figures. I countered with a $7k discount which put the price around $10k (offer has not been formally responded to yet) Even if I spent $12k on a rebuild, I'd be at ~$22k which is what a lot of ~100k mile cars with no rebuilds go for. Since the rebuild would be coming from a highly respected shop, I'm guessing this would not be money poorly spent, nor would I consider this to be too far 'underwater'.

pcarhiway

Just as an example ...

Last summer I was looking at a very nice 1996 Carrera 2 (993).

It had around 44,000 miles on it. The motor had been rebuilt at 38,000 miles. Receipts from a Porsche dealership 1.5 years earlier were $16,000.

Based on the asking price the new motor only added about $4,000 in value to the car. ($39,000 vs. $35,000) compared to a similar car with no rebuild.