930 leakdown quandry (need quick turnaround)

[kilodawg]

To distill this to it's essence. This is a private sale. I'm looking at an'86 930 with a little over 63K miles. the tranny was rebuilt less than 1K miles ago along with other work including a 60,000 mile service.

At the time the (well respected) Porsche service facility (they only work on air-cooled cars and have a good reputation) noted the following leakdown numbers and I'm copying this exactly:

#1 > 12%
#2 > 8%
#3 > 8%
#4 > 4%
#5 > 16%
#6 > 4%

I saw the receipt and immediately consulted my wrench who is confused as to how this can be interpreted as anything but bad.

However, when I spoke to the shop about the car yesterday (prior to seeing the car) I was told nothing but good things about it. I haven't been able to get through to the shop owner yet for an explanation but the seller said he recalled some conversation that they had at the time about the car being cold when it was done and having somthing to do with the higher numbers.

Anyway this could be possible and? I'm going to have them perform another leakdown anyway but this could be the potential deal breaker.

[dean]

If I were going to make an offer on that car. I would offer his asking price less the cost of a motor rebuild.

Here is a data point. I bought a used early 930 motor. When I got it here the first thing I did was a leak down on the cold motor. The #'s ranged from 1% to 2.5%. The motor still runs great.

[kilodawg]

Thanks Dean,

Anyone else want to chime in? Looking for a consensus and am on a short turnaround here.

[imcarthur]

Numbers like that - with matching compression #s scared me away from 2 cars during my hunt. Rather than risk it, get another leakdown & compression test - maybe from a different mechanic too if possible. Just my uninformed opinion . . .

Is this the one you drove on the weekend run?

Ian

edit: I checked the numbers on my old PPIs & they were much higher. 50% & 55% leakdown etc. Yours are much lower, but still worthy of another test.

[David E. Clark]

Those numbers are scary. If you are really interested in this car, pay your wrench to do a proper leakdown test. It would be money well spent in my opinion.

[kilodawg]

Ian,

Not the one from the weekend run.

This one has me second guessing. The interesting thing is that the shop says they stand by the leakdown results and said that another would be a big job that would probably not yield different results. Basically, they said that in their opionion I should either get comfortable with the numbers or pass on the car. However, they believed the engine was solid and they did not see the numbers as a source of concern. I was also told that in looking at each plug when they were removed they were all in equally good shape and the engine did not burn oil and drove very well.

I don't want to pass on this car if it's good but I don't want a money pit either......

[mmastro]

Anything approaching 10% is suspect. Anything over 10% = a rebuild in your future. 930 motor rebuilds can get very ugly very quickly in terms of cash spent. If it were me and I didn't have the $20K for a complete rebuild, I'd pass. just my $0.02...

[kilodawg]

Latest in this saga is as follows and I'm sure I'm not stating this as technically accurate as possible but I was told again by the shop owner who has worked on the car and performed the leakdown something to the effect that cold leakdown numbers were worst case and you could deduct 25% from those values if you injected oil into the cylinders(?) These leakdown numbers were not done as part of the owners PPI but were performed by the shop as SOP with any major (in this case 60K) service.

[cygtoad]

It is not the percentages that are spooky but the large variation between the cylinders. They shouldn't be that far off from one another. A well cared for engine should wear evenly, not be all over the place like this one.

This thing is just waiting for the chance to fly apart.

[Bruce M.]

Agree. Spread is too wide. Pass, unless the price is low enough to do a proper rebuild.

[89turbocabmike]

I also am concerned about the variations. A good warm leakdown test along with listening to determine where the leaks are occuring could help to explain some of these problems. You could perhaps get away with a top end rebuild though it's likely the "while your in there" virus will launch. There are lots of turbos for sale out there, take your time.

[axl911]

Have the valves been properly adjusted?

What are the compression number?

[David E. Clark]

You might want to reread Wayne's article Time to Rebuild? Part II which discusses compression and leak-down testing.

According to this article, "a newly rebuilt engine should have leak-down percentages of around 3-5%. An engine in good running condition should show 10% or less. Numbers around 20% indicate some wear of the engine, but are still adequate for good engine operation. Leakage numbers of around 30% indicate that there are problems brewing, and that a rebuild may be necessary. "

I agree with the others who have said that it is not how high the numbers are (but I am concerned about cylinder number 5) it's the spread that's very worrying. To have cylinder 5 so much higher that cylinders 4 and 6 is a problem in my opinion.

Finally, the "shop owner" is correct that if you squirt some oil in the cylinders it will improve the leakdown results a little, probably not 25% but maybe 10% (from 20% to 18%). Leakdown numbers are not like compression numbers which can be improved a lot by squirting oil in the cylinders. In my opinion, however, "improving" the numbers by an equal percentage will do nothing to change the spread of numbers and that is really the problem here.

[kilodawg]

Hey, I want to thank everyone for their replies. it's what makes this forum so great.

I wanted this to work out in the worst way. The timing was good for me, the car was close by and with very little clean up I could have turned this into my dream car.

But the leakdown numbers just didn't sit well. I was looking for anyway to rationalize it but you guys kept me honest with myself and more importantly kept my impulses at bay.

Thanks until next time!

[cygtoad]

This 930 is like the hot sexy girl that your freinds warned you about. You know they are right, ....but....but... she is right there and she wants you!

Man, that hurts. We feel your pain.

Cheer up! Really you have your pick of hot sexy girls and few of them are as emotionally unblanced as this one.

[Por_sha911]

Originally posted by kilodawg
the (well respected) Porsche service facility (they only work on air-cooled cars and have a good reputation)...I was told nothing but good things about it.

Note to self: do not ever use this "well respected" shop. They either don't know what they are doing or are dishonest.