Erratic Leak Down

New KB15 Block with all new rotating assembly. Pro Assembled ( Not by me!) and fresh from the machine shop. Never started.
Took a leak down of all 8 with 70lbs in they read from 65 all the wy down to 15lbs! Not leaking past the valves but into the pan / past pistons. Is this normal for a engine that has not yet been run/started. Do the rings seat themselves when it warms up? Thanks.........Browmman

 

after reading this i am not sure how you are "leaking" it
are you using a leak tester as most need 100 psi or at least my C&A one does

 

I'm using the TAVIA Leakdown Tester unit. If I run it up to 90lbs the results are the same. Air is pouring past the rings. The question actually is "do these engine have to fire up to seat the rings? Brownman

 

I have found the same thing as Mike. Much depends on how the engine was put together. Was the pistons and rings assembled dry or with oil? If with oil and it has new sleeves you should get a good leakdown result. With new sleeves and even after making a run mine usually reads below five percent. However when you have a cyl that doesn't you should back the cly up about 50 degrees and pull against it with the bar you turn the motor up. It it comes down low enough this way it means the dykes rings expanded against the cyl walls and sealed.
One other thing you might do is run a compression check on all cyl. and note if you have the same results as with leak testing. My bet is that you want. This used to bother me when a cyl leaked say 40% until I started using the method above and the same as Mike. If it doesn't come down you probably have a problem with that cyl.

 

im not a blown alcohol expert, but ive built alot of race engines and i can tell you now that a leak down test on an unfired engine is worthless, especially with steel or hellfire rings, which im assuming your engine has. the readings are always eratic. sometimes youll get a cylinder that will seat during assembly, while others wont.

on an engine like yours (i.e. not a turd) youll seat the rings after the first sixty footer, if not the first two minutes of idling.

 

Thanks for the input. hard to reach people on a Sunday afternoon and I need to install our backup after some nasty damage at Maple Grove. Engine was machined at rage and short block assembled at BNR so I'm thinking that you guys are on the money. Will give it another try. Reading are so wacky that it has to be something consistant. Only one cylinder reads 68Lbs after 70 lbs is forced into it. This block has new C&A rings, new pistons,Rods and appears to be assembled with some lubricant. Isn't this FUN!
Thanks Again..Brownman and the FNG's

 

News Flash!
Just got a call from Mike at BNR and he tells me that the rings will not seat until the engine is fired and cylinder put under pressure. This is good to know for all us FNG's. Thanks again for the help. Brownman