Help interpret Leak Down results

B6/7 S4/RS4
#1

Looking at a 05 S4 Avant for sale, far away from me. Had a PPI done including compression+leakdown tests.

Compression all came back OK (max-min difference was 15psi)

Leak down however, got numbers between 12% and 30%. And this is what is throwing me.
From low to high: 12, 13, 15, 15, 15, 17, 25, 30

I know compression results are more about the difference rather than the actual number due to different factors in battery, temperature, dry/wet, yadddayadda

On the other hand, I thought leak down was a bit more “repeatable” since it was static test. Are there factors that would significantly move the baseline (from what seems to be the typical 1-4%) up to that 12-15% range? It seems odd they were all over 10% when everything I’ve dug up on other leakdown on a b6/7 s4 seem to have the vast majority well under 10%.

I don’t know the specifics of how long they held the test and that is all I can think of as the reason. I know you can’t hold pressure indefinitely and you will lose some eventually.

So am I just trying to reason myself into a new-to-me car or are there legitimate concerns with those leak down numbers? FWIW the shop mentioned the spark plugs were pretty dry, and the exhaust tips/back end of the car wasn’t oily (at the time) so that’s a plus. Current owner (wolfs4) claims ~1qt/5k miles oil consumption which doesn’t seem bad but I -or the shop- cannot verify this during a simple PPI, obviously.

Many thanks

#2

I think wolfS4 is on here.

Fist I would start with the compression test. Really its suposed to be one way and results from the compression test help give a guide into how to look at the leak down test.

You are right in general leak down results are less then 10 on most S4 tests I have seen.

I would start with what the actrual compression numbers are dry…

As for the oil burning. If its 1 quart every 5k thats good. Most cars even new S4s eat about 1quart every 1500 or so

#3

Thanks. Yeah I’m pretty sure he is a forum member, not sure how active anymore. Compression numbers were all between 140-155, dry test, which seems pretty typical and aligns with my own vehicle.

The shop couldn’t say where the leakage was going (i.e past rings, or past valves into crankcase/exhaust) so I’m not convinced they did the most thorough leak down. I would be more skeptical if one tested at like 4% but the lowest was 12%. But still, 30 is pretty high.

Oil consumption at 1qt/5k mi is lightyears better than my current one which has only gotten worse over the years. But I also don’t want to buy an engine that is on it’s way out.

#4

if they cant tell you where the leak was going, they didnt do it right

I personally dont like any leak down number over 10% but anything over 20% is bad news

#5

Yeah I’m getting the feeling they weren’t too sure how to conduct a proper leak-down test. :-
Guess I’ll be taking a gamble ;D

#6

What shop?

#7

Absolute Automotive in Durham, NC
http://www.absoluteautomotive.com/

#8

The not burning a ton of oil is really one of the biggest parts of my usual concens when I look at a cars health.

Why this car. is this a wagon and your looking for that…

#9

bingo

#10

Not to talk you out of that car but given how hard wagons are to find.

A neat trick you can do and I dont know how much your spending but you can find a allroad with the 4.2 motor and just do the JHM 6speed conversion. To me the allroad looks just like the S4.

I never really looked at the domensions but I think you might even get a little more room out of the allroad.

either way keep us updated. Its always great to see new pics of these great cars.

What are your plans with the car.

#11

Avants forever!!! Just turned 116,xxx on mine and had to spend almost $1000 to replace all the power steering hoses to make the power steering work again. If you want to gain some upper body muscle mass, pull your fuse that supplies the power steering. Ask me how I know. Love/hate relationships help make the world go 'round!!

#12

Yeah, I’ve basically bought the car, just waiting on the shipping and actually getting the car here before final payment and title transfer. It’s going to need some TLC and work to get back tip top shape but nothing I can’t handle. Trying to use it to convince the wife I need a set of quickjacks for the garage ;D

I hear you, I swapped the entire rack in my S4 sedan twice in a week this summer… while on vacation. >:(

I’m probably slightly insane for planning to own two B6 S4s… I guess if anything I’ve got lots of practice with working on it lol