Arrwin

Hey guys,

Just looking over some documents I received with the car. When the PO bought the car he had a PPI w/ a leak down test done.

The results were as follows:

#1 @ 6%
#2 @ 4%
#3 @ 4%
#4 @ 4%
#5 @ 4%
#6 @ 5%

How do you decipher these results? I'm assuming the lower % the better?

Thanks again.

Crimson Nape Racing

when I sold my 84, the leakdown was similar to yours. My mechanic said a brand new engine would be 3-4%, and anything in the 5-6% range was still excelent. I do not remember what he said was "too much", but I do know your numbers are excellent.

Arrwin

Great! Hope it keeps this way as this was 2 yrs. ago.

When does it get unacceptable?

garychios

Great numbers!!

cooz

great leak down numbers....like new.

even up to 10-15% leakage is okay

cooz

traveller09

I have been told 3-4% is a good strong engine and up 10% can be acceptable, but not to go over 10%. I closed on a 91 last year, contingent on a PPI. It was a one owner 34K mile car and it two Valves at 16 and 18%. The best 2 only got as low as 6 and 8%. A friend of mine who is along time Porsche guy told me to Run, so I did. I am still looking, although now I am leaning more towards a 993. I am so gun shy after that 91 that I won't buy an air cooled Porsche with out a "Cold Engine Leak down".

Steve Weiner-Rennsport Systems

Hi Arrwin:

First, I'd tell you that these are Leakdown test results, not compression test numbers,.....

These are good numbers but I must stress something for those who do not know how to interpret things like these.

A leakdown test is performed by pressurizing each cylinder with air at TDC. With the valves closed, one can measure the percentage of air leakage and most importantly, allow you to determine the SOURCE of any leakage. Without that critical observation, the test results have little context.

With each cylinder pressurized, the technician listens for air hissing from the air cleaner opening (leaky intake valves), the exhaust pipes (leaky exhaust valves), and the oil tank filler cap (leaky rings).

Now,....THAT really gives you an accurate "snapshot" of the engine's health. Anyone having this test done either as part of a PPI or the engine's "physical" should ask for that followup information to tell you anything worthwhile.

1-5% is just fine

6-12% requires some further investigation

12% or more will cost someone some money at some point

20% or more requires immediate resolution

FlyYellow

steve,

thx for the description - excellent explanation of leak down testing and what we should all ask for...

Cheers,
Boris

Arrwin

Hi Steve,

Thank you for the correction. I had stated it correctly in the post, but didn't change it in the heading. It has since been revised.

Thank you for thorough explanation of these test results. You have once again served this Rennlist community in a great manner.

One question: Is it safe to assume that as these car gets older, the percentages will increasingly get worse (increase in %s) and eventually result in 'costing someone some money at some point'?

dcdude

Steve W. (or anyone else):

What is the instrument on which the leakdown %age is measured? Is it a dial gauge like a compression tester? Anyone got a pic?

Thanks,
Chuck

mhm993

As always, a truly useful, understandable, and succinct response from Steve W. Terrific as always!

Bull

And the test should be done when the engine is at operating temp.

TheOtherEric

This thread is like 3 yrs old, by the way.

mhm993

3 years old....NOW I notice.

Well, Steve was good then, and he's still terrific to us, now!
Marc

TheOtherEric

lol, it took me a long time to get into the habit of (a) looking at the date the thread was started and then (b) reading the entire thread. No more of spending 5 minutes reading then finally thinking "gee this all sounds vaguely familiar...[checks dates]...Doh!"