911 3.2 Feedback on leak down and comp results
 

Shareing my results for a prospect 1988 911 3.2 as general reference and for any feedback from those that might know a thing or two.

Car currently has 55k miles on it and has been driven less than 1k miles per year on average between 93’-19’ by it’s current owner. It has sat undriven regularly for the most part over the last 10 years.

Results from the PPI are:

Compression test dry #1 = 135, #2 = 140, #3 = 120, #4 = 135, #5 = 150, #6 = 150 (add .2 for wet compression retest)
Leak down warm #1 = 9%, #2 = 8%, #3 = 12%, #4 = 5%, #5 = 5%, #6 = 4%

#3 cylinder seems suspect for a leaky valve since wet and dry readings we’re consistent from what I’ve learned. Could also simply need a valve and timing adjustment.
Any other thoughts based on the results alone?

Cheers!
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Any high leakdowns Should be rechecked after getting it hot and driving around. Could just be carbon on the exhaust seat from removing the plugs. Was the comp test run on a hot engine or cold and been sitting?

Your numbers show one side of the engine uniformly lower than the other side of the engine in compression and leak down. Additionally, the engine has been sitting for the better part of 10 years. It does not indicate to me that one particular cylinder is troublesome more than the other five cylinders. I would suggest that something is off with the valve timing on bank 1 vs bank 2.

If it were my engine, I would not go straight to a valve job, not yet. I would re do the valve timing, adjust valves, and run the engine for some miles and then retest. Like JW, I would trust these tests more if they were performed on a warm to hot engine.

A valve timing issue could affect compression readings (but minimally?) but would have no effect on leakdown. Unless the timing was way off and then the car would run rather oddly.

IMHO... change the oil, check the valve adjustments, check over brakes, tyres, etc and then put a few hundred spirited miles on the car and rest test.

all -- note that the OP is looking at "a prospect 1988 911 3.2 " and that the leak down results are part of a "PPI" -- advice above (with the exception of John W's advice to recheck hot) all make sense if the car belonged to the OP . . .

The beauty of the leak-down test is, not only do you get an indication of the cylinders ability to hold compression....but where it is leaking from. By listening...you can determine if the leak is at the intake valve, exhaust valve and/or rings.. if all numbers are low & good...no worries...
Based on the leak-down numbers above, it would be good to understand where it was leaking........

If the engine has been sitting for some time...as John stated, it is definitely worth running it until hot and testing again....I've had engines that had pretty leaky results....but got much better after several "spirited heat cycles".

regards,
al

Thanks John, the car was “hot” according to the shop. They stated that they drove it for 10-15 minutes in the higher rpm range before starting the test.

Thanks @yelcab1, does confirmation that the car was hot during the test change your suggestion?

Thanks yelcab1, does confirmation that the car was indeed hot during the test change your suggestion?

Thanks yelcab1 for this perspective. Does anything change since I confirmed the test was indeed done while the engine was hot?

Also, do you have or work at a shop on the peninsula?

Here are a few underbody pics from the PPI:
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I'll admit the underside is a little crustier than I'd like to see. It's hard to really evaluate without knowing what you know as the buyer. More about the history of the car, and it's price.

Personally, I'd prefer a car that's been driven. A car that's sat for 10 years is going to have some deferred maintenance and you are going to discover them as you drive and enjoy the car. As long as the price takes that into consideration and you look forward to that part of ownership, it's not an issue.

That underside is not "crusty" at all. WHat you are looking at is cosmoline on the engine and suspension components. Personally, I think it looks pretty dry.

I appreciate the reaction and comment. If you’re referring to the corrosion on muffler and other bits this is likely due to the car residing in a state where road salts are used. Albeit, a state with moderate winters but still this probably had an affect on the underside.

As for the engine block and suspension parts, I agree with CCM911.

Car is a two owner vehicle for the record. First 34k miles are undocumented by CARFAX. After that it resided in the Midwest from 1993 onward. Good frequent on schedule service history and body panels and paint are all original.

My thoughts are it needs to go for a HARD four hour drive. Lots of full throttle up hills, 5,500 and 6,000 RPM gear shifts. Really warm it up and burn off some of that residual carbon inside the cylinders and sitting on the valve seats. Then try again.

Retesting after some driving is a good idea. I would do the leak down on a cold engine as it’s easier to spot problems and that’s how we did it at the engine class from Porsche. There are usually very low cold leak down numbers on these when just broken in Compression on a warmed up engine as usual.

Very interesting! I have yet to hear this. Thanks.

Well that’s the plan and I have a nice set of rolling hill climbs where I’m at if purchased.

The car is a virgin looks very clean. My former 3.2 was very similar. Did an underbody DEtail and all that cosmoline kept things very fresn if not a little ugly!

I’d do a full maintenance schedule and tune up on it get everything current and a valve adjust go drive the crap out of it. Negotiate for a valve job at some point in the future.

Thanks for all the responses. The feedback gave me the info I needed to fill the gaps in the report and lack of specifics provided by the commissioned mechanic shop. Car is purchased and on its way to sunny California. http://forums.pelicanparts.com/suppo...sun_smiley.gifhttp://forums.pelicanparts.com/suppo...s/beerchug.gif

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