Engine leak down test

[george21]

Just wanted to ask if anyone done a leak down test on the cylinders?
And what results do you get? I have done few days ago and i got between 15-20% on all cylinders. Is that good result or bad on our 20v engines?

[LSG]

Are you talking about a leak down test or compression test. ?.

[george21]

Are you talking about a leak down test or compression test. ?.

Leak down test.
To test how much is leaking through piston rings into the sump,
Also to see if valves or headgasket is leaking.

[Rikki Kitto]

This sounds like a compression test to me

[AndyP]

How many miles has the engine done?

[LSG]

If it's 15% - 20% that's quite low. I don't think I would loose any sleep over that. I guess your testing a used motor not a rebuild one. Also makes a difference on air supply and motor in tdc but you did all that.

[george21]

If it's 15% - 20% that's quite low. I don't think I would loose any sleep over that. I guess your testing a used motor not a rebuild one. Also makes a difference on air supply and motor in tdc but you did all that.

Yeap. Done it on tdc. Engine done around 120k, but who knows if it is correct, as i bought engine for coversion on my ur. Reason i done it that i got smell of fuel from the sump. And thought that under high boost 1.8 1.9 bar i get the leak of it into the sump. And it will pressurise oil in the sump as well which will affect oil draining from the turbo making it to fail. I have 3 turbos that failed so far.

[george21]

This sounds like a compression test to me

Not trying to be smart here but it is completely different test. You pressurise cylinder bore on tdc to check for leaks through the rings etc.

[tomwood_uk]

If it's 15% - 20% that's quite low. I don't think I would loose any sleep over that. I guess your testing a used motor not a rebuild one. Also makes a difference on air supply and motor in tdc but you did all that.

Agreed, doesn't sound bad for 120K. As long as all cylinders are consistent I wouldn't be alarmed.

[AndyP]

Knowing how robust these engine are I would have expected better than 20% for 'only' 120k miles. My old 3B enine had around 195k miles on when I pulled it and it ran perfectly, none of the symptoms you descibe.

When you were doing the leakdown test, could you tell where the lost air was going, exhaust, inlet, cam cover etc. This should help narrow down your problem. Have you done a compression test?

[george21]

Knowing how robust these engine are I would have expected better than 20% for 'only' 120k miles. My old 3B enine had around 195k miles on when I pulled it and it ran perfectly, none of the symptoms you descibe.

When you were doing the leakdown test, could you tell where the lost air was going, exhaust, inlet, cam cover etc. This should help narrow down your problem. Have you done a compression test?

Compression was checked before and it was ok, can't remember what exactly numbers were. Will do it again just to double check.
It did not leaked into inlet or exhaust, sounded like into the bottom somewhere which could be only sump, but didn't feel any pressure on breather pipe
( it is open into atmosphere )
Unless it leaks through the headgasket
Can't figure out what is causing turbo to fail so come to idea that it leaks compression to the sump and stoping oil to drain from turbo which makes it to starve of cool oil. Plus i got smell of petrol from the breather as well.

[LSG]

Your compression test was ok on all cylinders. Your not getting excess crankcase pressure. This would suggest no cylinder problems. Do the compression test again with some oil down each cylinder see what it go's too. If your head gasket had gone you would have coolant back filling the expansion tank or mayonnaise for oil. Do you know what your compression should be on this engine.