Leak down % on "good" not new engine?

[twinrats]

Anybody have experience on what leak down percentage should be on a "good" engine (109 w/JE pistons without gapless rings)/ Engine ran 9.98@138 in race car.

 

[JayC]

Depends on how worn out it is but anything in duble digits, Id probably avoid. Ive run stuff higher but not usually out of choice.

 

[cpac]

will leak numbers be affected if rocker shafts are not removed

 

[chasmat2316]

Valves must be closed!

 

[Underboost]

6 is what I like to see.

 

[twinrats]

Leak down

Looks like I've got some issues on the "freshend up" engine I just purchased. It's been out of the car since last December, seller said he tore the engine down to "freshen it up" and the pistons, rings and cylinder walls looked good so he put new bearing in and re-assembled without new rings or pistons. Since the freshing up seller said it has about 5 passes on it. So before I had it reinstalled the shop did a leak down test and got 30% leak down. They said that there was no signs of leakage passed the intake or exhaust valves.

 

[Alky V6]

Looks like I've got some issues on the "freshend up" engine I just purchased. It's been out of the car since last December, seller said he tore the engine down to "freshen it up" and the pistons, rings and cylinder walls looked good so he put new bearing in and re-assembled without new rings or pistons. Since the freshing up seller said it has about 5 passes on it. So before I had it reinstalled the shop did a leak down test and got 30% leak down. They said that there was no signs of leakage passed the intake or exhaust valves.

That's too much! Even for normal rings.

For future reference. Total Seal Gapless tops have consistantly given me 1 to 2 percent leakdown, no matter what the life of the engine. I have yet to see a higher leakdown number with these rings. 4 different engines tested so far.

 

[twinrats]

OOPS!!! Leak Down is REALLY 10%!!!

just heard from shop installing motor and the gauge they used to test the engine was BAD. They re-tested engine with new gauge and it tested out at 10%! :biggrin:

 

[lazaris]

Was that with the engine hot or cold? With a std file fit ring engine ice cold I have between 4-6. This is on a motor with about 40 passes on the short block.

 

[twinrats]

Engine has been out of service since last December....so it was cold and dry. The rings are file to fit...not gapless

 

[lazaris]

Then 10 isnt bad.

 

[MSDGN]

That's too much! Even for normal rings.

For future reference. Total Seal Gapless tops have consistantly given me 1 to 2 percent leakdown, no matter what the life of the engine. I have yet to see a higher leakdown number with these rings. 4 different engines tested so far.

My Total Seal top gapless were around 2% when I first built the motor...last time I checked after 3 years and probably 100+ mid 10 second passes they were between 5-6%...still OK IMO...plus this was on a stone cold motor...BTW the car ran almost 132 MPH after I did the leakdown...

 

[vacuum 6]

Good read