leak down test

[coza]

Hi

 

Last year I put a whifbitz stage 3 catch tank on the car and noticed that it breaths heavy it was twin turbo never ran over 1 bar never misfired or any signs of a tired engine , I done a compression test in December didn't use the best test it showed that all cylinders was near enough 11 bar ,

 

since then cars had a single conversion , but still breathing heavy no misfire or any signs of it being tired, leak test being done this week ,

 

does anyone know what the car should be getting ? i.e good results ?

 

thanks

[Mike2JZ]

For a healthy road going engine you don't really want to see more than 1-15% leak on each cylinder. Anything more could indicate a loss of performance on that cylinder.

 

Considerably high leakage (40%+) could indicate inproper sealing from rings/valves/headgasket etc.

 

Engine breathing isn't necessarily a sign of damage or anything to be concerned about btw. Results from compression/leak down and your average oil consumption is more of an indication of engine health imo.

[coza]

For a healthy road going engine you don't really want to see more than 1-15% leak on each cylinder. Anything more could indicate a loss of performance on that cylinder.

 

Considerably high leakage (40%+) could indicate inproper sealing from rings/valves/headgasket etc.

 

Engine breathing isn't necessarily a sign of damage or anything to be concerned about btw. Results from compression/leak down and your average oil consumption is more of an indication of engine health imo.

 

brilliant, cheers for that

[Dnk]

https://www.hotrod.com/articles/cylinder-leakdown-tester/

[Tricky-Ricky]

What do you call breathing heavy, and from where, it doesn't always mean that its piston blow by, could be from a faulty non return valve in the PCV system, how have you got the breathing configured? std or catch can etc?

[coza]

Leak test done 14% - 18% across all cylinders, leak is blow by past rings and not through valves , compression test done too ranging form 11 - 11.5 bar , cylinder 2 and 5 im told was oily.

[Tricky-Ricky]

Not i figure i would worry about, and certainly not a cause of the blow by your describing, as i have already asked what are the symptoms, are you just seeing a bit of oil or emulsion in the tank or does it pressurize the outlet/vent?

Ring seal on a turbo engine increases with the boost pressure so unless there is damage to the rings its unlikely to be the source, i have tested crankcase pressure on my supra and found that even as high boost with twins there was no pressurization with the std PCV system or modified and using a catch can.

[coza]

what's happening is the catch can is not filling up oil is coming out of the filter its self seems like there is a lot of pressure and I've just got to keep cleaning it,

 

this is the set up, http://www.garagewhifbitz.co.uk/garage-whifbitz-1625.html

[Tricky-Ricky]

So oil mist is being trapped by the tank breather but not accumulating in the tank, there is always going to be some oil mist present, how do you know there is actually pressure present? personally i always advocate running a feed from the catch can back to the turbo intake similar to the std setup as this will make best use of the vacuum effect from the turbo intake which is useful for crankcase negative evacuation, and helps promote both ring seal and oil seal, most engines breath rather heavily IE create a lot of oil mist at idle and low load and that's usually why you see oil mist, its normal for a catch can to be needing emptying about once every couple of month's with normal use depending on how much engine heat its exposed to.