Question about leakdown issue found during PPI
 

I've been thinking about buying my first Porsche for a few years, but recently started to look seriously. I came across something that checked all the boxes on my "want" list: 1987 911 targa, nice rare option color, relatively low/normal mileage for its age (120k), and most consumable chassis parts replaced recently (clutch, shocks, axles).

I had a PPI done and was satisfied with the initial results of it, but asked the mechanic to do a compression and leakdown test as well. Unfortunately the leakdown test uncovered 32% leakage in cylinder 2 :( Leakage was within spec on all other cylinders, but compression on some (I think two of them, not sure which) was at 115 and the mechanic said he would expect to see more like 140 if the engine were totally healthy.

My first instinct was to walk away, but I told the seller I would think about it over the weekend. I have more than average mechanical/car experience and knowledge, so I understand the general implications of the leakage and poor compression. I just didn't think I wanted to buy a car and probably jump right into a bunch of engine work. I would prefer to buy something that was ready to drive and enjoy for awhile first, knowing that the Carrera 3.2 engines usually need a rebuild before they get to 150k miles. But now I'm reconsidering, because everything else about the car is what I want, including the uncommon color and the fact that it's a targa. The only other things it needs mechanically are front tie rod ends and attention to two minor oil leaks. I also have a specific desire to find an '87, because I may be moving overseas in the future, and if the car is more than 30 years old when I do I can keep it left hand drive. 1987 would be the NEWEST year I could buy to fit that criteria, and there were fewer than 300 targas sent to the US in '87.

I'm going to call the mechanic tomorrow to ask a few more questions and get his opinion, he was great to talk to through the process so far and seems very knowledgable. He only works on Porsches. The only other real question mark is that the maintenance documents are incomplete past the prior owner, and the seller is just a buy and resell guy so he can't shed any light on that. He is prepared to reduce price based on the issues found if I'm still interested. I have the budget to cover repairs so that's not an issue. I'd love to hear anyone else's thoughts and advice. Thanks!

If everything is what you desire, at 120K they are overdue for a top end .
A fresh top end will give approx 170 # on compression.
Bruce

Not to mention after you do the engine work, you will have piece of mind that there will not be any surprises. I think finding a car which checks all the boxes is harder than an engine rebuild. If this is the car you want go for it. You will be doing engine work on a car you want compare to getting something which is not optioned they way you want...

It would be helpful to know the source of the leak: intake valve, exhaust valve or rings. You can hear the leak at the intake manifold, the exhaust pipe or the oil tank, respectively. What did your mechanic report? This leakdown result could be something as simple as carbon on a valve that will break loose with a long drive.

The leak down must be performed correctly, or false results can occur. DO NOT remove all the plugs at one time, and then do the test. Carbon bits can break loose from the tip of plugs, and fall directly down onto the seat of an open valve. When that happens, and the engine is turned to the cylinder to be tested, the exhaust valve closes against the carbon debris; which is too hard to be crushed. The result? 30% leakage.

Always put the engine on TDC for the cylinder being tested BEFORE removing that spark plug. If the test was done wrong, drive the car a few miles, let it cool off, and re-do the test.

If the leak down is real, I would buy the car and discount the cost of the valve job.

I do not agree on the 120K car needs a top-end anyway mindset... It's all about the frequency it was driven, how it was stored and cared for. There are many un-opened high mile examples on this forum.

I'm just not one to toss $10k at something for "a piece of mind".

My car has ~45k on a "new" top-end. Last year I had a leakdown done and #2 was 45%. Come end of last year the thing was making a terrible noise, what I initially thought was detonation. Fast forward to 150miles of driving this year and the noise grew, exponentially...

Now were 85-90% leakdown, #2 exhaust side. Noise is compression passing valve guide. At 177k, I will eventually do a full teardown.

All numbers aside from a single cylinder being good, it's likely a problem that will manifest into a larger one.

If as you say, the seller will be reducing the price based on the issues you found, what's not to like? If he discounts it enough to make it worthwhile, you'll end up with an engine that's a known in terms of top end. Plus you said you have to fix some leaks anyway. Seems to me you end up ahead of the game.