20% on leak down test audi a6 3.2 good or bad??

[Chad Olson]

I did a leak down test on my Audi a6 3.2 after installing tensioner driverside and all cylinders were 18% except one cylinder that was 20% I was just wondering if them numbers are good for engine to run decent???..I bought the car from a friend that told me it was running fine before tensioner started making nosie ...can someone help me out

 

[Mario]

No engine will have perfect sealing with 0 percent loss. Five to 10 percent loss indicates an engine in great to good running order. An engine between 10 and 20 percent can still run OK, but it’ll be time to keep an eye (or ear) on things. Above 20 percent loss and it may be time for a teardown and rebuild. Thirty percent? Major problems. The percent of leakage should also be consistent across the cylinders. Any great differences indicate a problem in that cylinder.

https://mobiloil.com/en/article/car-maintenance/car-maintenance-archive/how-to-do-a-leakdown-test

It's on the limit of what is acceptable to be honest, but it's not at the point of needing a rebuild yet either.

Was the engine hot when you did the test? It should always be at full operating temps, as metal expands and creates more of a seal when hot, so it will give a more accurate reading than performing the test on a cold engine.

 

[Chad Olson]

No I actually did it on a dead cold motor and it's very cold here in Wisconsin like 30 below

 

[Chad Olson]

20% was on a cold motor

 

[Mario]

The test is meaning less when it's cold. As it could be 15*c or -15*c ambient temp. However when the engine is at operating temp it will always be about the same, regardless of outside ambient temps.

Re-do your leak down on an engine at proper operating temps to get an accurate reading. I'm also positive you will get better results when it's warmed up like it's supposed to be and the the metals expand / gaps reduce.

Give it a go and let us know how you get on.

 

[Chad Olson]

Thank you for replying back .. but I can't do the leak down test when engine is warm because I am redoing timing chains so chains are off right now.. the reason why I am doing that leak down test is because one of the tensioners failed and started making a rattling sound.. I just want to make sure the valves are not bent.. what numbers will the leak down test show if the valves are bent?

 

[Chad Olson]

I am trying to avoid pulling the heads off don't have much money to do extra work....

 

[Mario]

what numbers will the leak down test show if the valves are bent?

Depends on how bent. However it would likely be a fair bit more than 20%, especially when testing the engine in sub -freezing temps while cold. 20% at the temps you tested at will certainly be less when the engine is warmed, so I would be pretty comfortable saying your engine is fine. However I would still do another leak down once it's all back together just for piece of mind, and I'm 99% sure it the warm leak down will yield even better results. As per my original post, even 20% on an engine is ok, but on the limit, and that's when hot. Yours being 20% when cold will be even less when hot.

 

[Chad Olson]

That's what I was thinking thank you for your help I really appreciate it it's sometimes hard to get a reply from people on here but you were great man thanks.. I am actually waiting for some parts in the mail to come so when I get it back together I will let you know how it goes thanks again