Need a shop to do a Leakdown test
06-04-2006, 02:16 AM
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Re: Need a shop to do a Leakdown test
Cylinder... already did a compression test and cylinder 7 came back 120psi and misfiring and the rest were 175 (+/-5psi). I think its a valve but I need to know for sure before I pul the heads. Thanks man
06-04-2006, 04:58 AM
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Re: Need a shop to do a Leakdown test
Originally Posted by DrewzR/T
Cylinder... already did a compression test and cylinder 7 came back 120psi and misfiring and the rest were 175 (+/-5psi). I think its a valve but I need to know for sure before I pul the heads. Thanks man
a vac. gauge will tell you faster if its got a burned valve or not. its possible, but rarely will a burned valve cause only 50psi of loss. most of the time its a massive loss.
and anyone with a compression gauge can tell you whether or not its a valve or not. just about every compression gauge set available (mine does at least) has an air hold adaptor that hooks to the hose, allowing you to pressurize the cylinder for doing valve spring service. use it, and listen to see where the air is coming from. granted, its a little more involved (you gotta make sure the cam is on base circle for the cylinder you are doing, etc) but its not that hard.
if its a 5.2 or 5.9 (i assume its on a dakota? or am i completely off base judging by your username?) its a damn good possibility of an injector issue. if you have one cylinder over fueling, it can wash down the cylinder and cause a low compression reading. a wet test will verify if its a ring issue or valvetrain issue. i have also seen cam lobes wear off on those engines, although its usually on cyl 1 or 2 though.
06-05-2006, 11:19 AM
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Re: Need a shop to do a Leakdown test
Originally Posted by fc735
a vac. gauge will tell you faster if its got a burned valve or not. its possible, but rarely will a burned valve cause only 50psi of loss. most of the time its a massive loss.
and anyone with a compression gauge can tell you whether or not its a valve or not. just about every compression gauge set available (mine does at least) has an air hold adaptor that hooks to the hose, allowing you to pressurize the cylinder for doing valve spring service. use it, and listen to see where the air is coming from. granted, its a little more involved (you gotta make sure the cam is on base circle for the cylinder you are doing, etc) but its not that hard.
if its a 5.2 or 5.9 (i assume its on a dakota? or am i completely off base judging by your username?) its a damn good possibility of an injector issue. if you have one cylinder over fueling, it can wash down the cylinder and cause a low compression reading. a wet test will verify if its a ring issue or valvetrain issue. i have also seen cam lobes wear off on those engines, although its usually on cyl 1 or 2 though.
and anyone with a compression gauge can tell you whether or not its a valve or not. just about every compression gauge set available (mine does at least) has an air hold adaptor that hooks to the hose, allowing you to pressurize the cylinder for doing valve spring service. use it, and listen to see where the air is coming from. granted, its a little more involved (you gotta make sure the cam is on base circle for the cylinder you are doing, etc) but its not that hard.
if its a 5.2 or 5.9 (i assume its on a dakota? or am i completely off base judging by your username?) its a damn good possibility of an injector issue. if you have one cylinder over fueling, it can wash down the cylinder and cause a low compression reading. a wet test will verify if its a ring issue or valvetrain issue. i have also seen cam lobes wear off on those engines, although its usually on cyl 1 or 2 though.
I've also swapped #5 injector with #7 and still the same results so Ive ruled that out. Ive also poured some oil into the cylinder during the test and got the same results and Im not getting any smoke from the exhaust so thats why Im assuming it may be a burned valve . Hopefully not a cracked head...these fockers werent cheap.....
I also pulled the valve covers off to get em powder coated and the cover with the bad cylinder has some serious oil buildup (kinda burned lookin) and the other is normal with the usual sheen of oil.
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