Leak down test on core engine...need suggestions
Leak down test on core engine...need suggestions Here's the data on my leak down test on my LS1 core I'd planned to use in my 91 RS
Front
42 ... 10
30 ... 12
12 ... 20
20 ... 10
It's got issues.
Suggestions on what I need to have done when it's apart being re-ringed/honed etc.
All comments welcome...even those from folks I like to argue with
Front
42 ... 10
30 ... 12
12 ... 20
20 ... 10
It's got issues.
Suggestions on what I need to have done when it's apart being re-ringed/honed etc.
All comments welcome...even those from folks I like to argue with
I can shift faster than you.
iTrader: (21)
Joined: Nov 2001
Posts: 5,133
Likes: 0
From: Baton Rouge, LA
First, find out where the air is leaking to. Typical rules of thumb are if you hear air coming from:
* the oil fill cap or crankcase - worn ring rings (if putting some oil in the cylinder decreases your leak down, then the rings are likely worn as well)
* exhaust port - damage exhaust valve/valve job
* intake port - damaged intake valve/valve job
* coolant passages - head gasket
Also, if you notice two adjacent cylinders with high leakdown, then the head gasket could be blown in-between the two cylinders.
You should also do a leak down on a hot motor for a more "real world" numbers.
Finally, you did make sure both valves on each cylinder were closed when doing the test?
* the oil fill cap or crankcase - worn ring rings (if putting some oil in the cylinder decreases your leak down, then the rings are likely worn as well)
* exhaust port - damage exhaust valve/valve job
* intake port - damaged intake valve/valve job
* coolant passages - head gasket
Also, if you notice two adjacent cylinders with high leakdown, then the head gasket could be blown in-between the two cylinders.
You should also do a leak down on a hot motor for a more "real world" numbers.
Finally, you did make sure both valves on each cylinder were closed when doing the test?
On The Tree
Joined: Nov 2002
Posts: 166
Likes: 0
From: Vegas
Leak down test on a cold engine that has not been running for a while will not be accurate. There are no oil in the rings...
I had the same issue on my spare engine, 5% in cylinder 1 but 25% for the rest. But the car ran fine when I swapped the engine.
Cylinder 1 and 3 seems to be pretty bad, can you see if there are any indications of problems?
I had the same issue on my spare engine, 5% in cylinder 1 but 25% for the rest. But the car ran fine when I swapped the engine.
Cylinder 1 and 3 seems to be pretty bad, can you see if there are any indications of problems?
Sounds are from the crank case. Valves were closed sure of that.
The motor is from a driveline that was pulled a few months back...I've had the engine for about 4 weeks...since the engine is on a stand...I'm not really sure how'd we'd get it warm for testing. It's cylinder 1 & 3 that are the main concern.
Plugs were gapped very tight and the oil pan has been tapped up front. Almost looks like an oil return point. The motor will probably get scoped today to see if it's rusted on the cylinder liners.
I know the guy I got this from has a forced induction set up. He insisted this engine had never had a power adder on it. Said motor has 26,000 miles and was his stock spare in case the motor built for his turbo blew up.
The motor looks very clean up top. The oil looks excellent too. Pulled the valve covers. No signs of excessive wear or damage up top.
I greatly appreciate the info...please keep it flowing...
The motor is from a driveline that was pulled a few months back...I've had the engine for about 4 weeks...since the engine is on a stand...I'm not really sure how'd we'd get it warm for testing. It's cylinder 1 & 3 that are the main concern.
Plugs were gapped very tight and the oil pan has been tapped up front. Almost looks like an oil return point. The motor will probably get scoped today to see if it's rusted on the cylinder liners.
I know the guy I got this from has a forced induction set up. He insisted this engine had never had a power adder on it. Said motor has 26,000 miles and was his stock spare in case the motor built for his turbo blew up.
The motor looks very clean up top. The oil looks excellent too. Pulled the valve covers. No signs of excessive wear or damage up top.
I greatly appreciate the info...please keep it flowing...
Last edited by 99 Black Bird T/A; Nov 20, 2003 at 07:17 AM. Reason: add details
