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Location: Davis, CA
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Leakdown-what's OK?

Folks-

I'm looking at an '87 930 with around 65k miles that looks cherry but the leakdown on the PPI came back with three jugs at or over 10% leakdown. Compression was from 152-160 psi.

Is this reasonable or is the motor due for some refitting?

Thanks.
Old 04-09-2010, 02:54 PM
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Porsche-Poor
 
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Has the car been sitting at all? Wondering if it needs a good romp and retest. While I'm no expert, i believe you want to see consistent compression readings across all cylinders and think leak down results under 10% for a motor with that many miles, what's the service history? Good luck with the purchase.
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Old 04-09-2010, 08:16 PM
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Wo ist die Rennstrecke?
 
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Was the test done on a cold or warm motor?

It really depends on where the leaking is coming from. If it is coming from the valves (listen to the intake or exhaust), it "could" be built up carbon on the valves and seats - not too bad. If the leak can be heard through the crankcase breather, then it's rings.

I would like to know what the other cylinders had. If all others are less than 5% and these three are more than 10%, it could be a carbon issue. If they are all within a couple percent of each other, then it could be normal wear and tear on a well used motor.

Do you know what the oil consumption is? If it's a quart every 800 miles or less, it might have a problem. The problem with measuring this on a prospect car is that you are taking the owner at their word on consumption.
Old 04-10-2010, 05:27 PM
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Guys-

Thanks for the replies.

The test readings are:

#1-158 psi/9%
#2-156 psi/10%
#3-152 psi/12%
#4-160 psi/7%
#5-156 psi/10%
#6-154 psi/11%

The PPI was done by a previous potential buyer who backed out and I haven't had a chance to talk to the wrench that did it yet so I'm not sure if it was done hot or cold or where the hiss was coming from. The car is at a dealer two hours from me on consignment and a bunch of stuff is not starting to add up but I may still invest the time to go over the car myself. If the car was cheaper, I'd probably jump on it but the seller wants $35k FIRM (his bolding, not mine) and based on what I can tell of the market right now, that's a bit rich for a car that might have a tired motor. The dealer also assured me it was a "local car" forever but CarFax shows history that refutes that and there is also some questionable stuff happening on the PPI with the front bodywork that might suggest a bloody nose that wasn't fixed right.

Again, thanks for the help and I'll report findings if I can break off some time to go see the car up close.

-JWL
Old 04-11-2010, 07:06 AM
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OFF THE BOOST PIPE NOW...
 
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If in doubt, either pass on it or get it priced right to get past those doubts. Too many others out there without questions.
Old 04-11-2010, 09:19 AM
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Wo ist die Rennstrecke?
 
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For the miles the motor has on it, IF the leak down was done on a cold motor, those aren't bad numbers. On a hot/warm motor, those numbers are a bit big, but not too much. It would be worth your while to travel there, and talk to the guy who did the PPI. Sometimes, these guys are not the sharpest tool in the shed which would help you make a decision. A good mechanic who takes his time explaining what he did is very important in the decision making process.

Good luck.
Old 04-11-2010, 04:59 PM
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Thanks, Don. It is a purty car so I am going to phone the wrench tomorrow to see if he knows his stuff.

-JWL
Old 04-11-2010, 05:34 PM
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JWL, I just recently purchased my 87' with twice the mileage...engine compression was off by 10% in 3 cylinders. Paid $25K. This was 14 months ago and i've just completed a $8K rebuild over the last 8 months. I found broken rings in 4 of 6 cylinders.

Be sure you know what you are buying into...if the motor needs rebuilding, the $35K asking may be a little high IMHO.

Good luck!
Einar
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Old 04-12-2010, 06:04 AM
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Need more information from the shop that did the PPI. My car, with similar miles, had similar PPI leakdown numbers (but I wondered about the knowledge of the tech, as he also told me compressions of around 90 psi were "spot on"). I had them re-do the compressions with a warm motor but they didn't re-do the leakdowns. So far I've added another 20K miles to the odometer. Take that FWIW.

But if you need imminent motor work, $35K is far too high.
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Old 04-12-2010, 03:05 PM
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Spoke to the wrench today and he seemed to know his eingang from his ausgang. Numbers were all done on a cold motor and the car has been sparingly if at all driven in the last four years. He told me he has worked on it for the last five and it's a nice straight car with appropriate marks for it's mileage.

So, sounds like she's worth a look and I will head up to check it out. Wish me luck and many thanks for all the input.

-JWL

P.S. My current '87 Targa knows I'm cheating on her. Went out today to take her out to run some errands and the battery was deader than Lehman Brothers. Figures.
Old 04-13-2010, 04:24 PM
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Wo ist die Rennstrecke?
 
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On a cold motor, the numbers above lead me to think its worth looking at. Ideally, you want to watch them start the motor if its been sitting for a couple of hours. A little blue puff of smoke is OK, but no big cloud and it should go away fast. When driving it, look for blue smoke under acceleration and hard decel. With those numbers, you should get neither.
Good luck.
Old 04-13-2010, 07:34 PM
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JWLindsey, I see your in Sac... I'm just 3 hr south of you.
I am going to put together a for-sale post here at PP for my 87 930 this weekend (45k orig miles. car needs nothing, engine is perfect)

Here is a teaser, a couple shots from the Historic's Laguna Seca parade lap last summer...PM if you want to see her!



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Old 04-13-2010, 07:54 PM
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