| Ken's leakdown check [message #235517] |
Wed, 08 January 2014 16:10  |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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"#3 cylinder's only
showing 130 psi vs ~160 for all the others, but we did a leakdown check that was OK"
Ken, is it possible that your leak down check passed because the hydraulic lifter on that intake valve is not pumped all the way up, like it is when the engine is cranking for a compression test, or running and puffing back through the intake?
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Ken's leakdown check [message #235521 is a reply to message #235517] |
Wed, 08 January 2014 16:37  |
Ultravan Owners
Messages: 443
Registered: March 2013
Karma: 0
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Senior Member |
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Terry,
I must say I'm confused with your statment.
A leak down test as you know; fills the cylinder with air and checks/test where (rings, valves - exhaust or intake) are leaking and by how much that cylinder may be leaking.
It has nothing to do with how the lifter is or is not pumped up.
That is another issue.
IF a lifter is poorly adjusted; a valve could be is held open or not open long enough. It would affect how an engine runs. It would either not allow compression and/or could back fire.
Sorry if I'm not too clear.
Tony (Ontario Canada)
Marie and I are blessed to have had a 2nd chance to buy our farm.
Still hoping and more importantly praying to be able to build a garage.
Our 1970 Ultravan #520 has an Olds Toronado 455 in back.
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| Re: Ken's leakdown check [message #235525 is a reply to message #235521] |
Wed, 08 January 2014 17:20 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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A leakdown test is static, with no oil pressure being supplied to the lifter, so the lifter can bleed down from valvespring pressure and allow the valve to seal. When the engine is running or cranking, oil pressure is supplied to the lifter and the valve may not close all the way if the rocker arm is adjusted too far down or an aftermarket cam is installed with rockers that are normally turned all the way down, like a Pontiac or Ford small block. Been there and done that and had to double nut the rockers to get the valve adjustment right.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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