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Old 03-02-2014, 05:56 PM   #1
gti_sean
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Default question for engine guys(im new to this)

so i bought a project car, 90' nissan 300zx non-turbo, and after doing a leakdown test it seems a majority of my intake valves are bent/out of spec, and when it ran for the few minutes that it did, it had lifter tick from a stuck lifter or 2.

anyways my question to you guys, i found a guy selling a complete motor with bad rod bearings, he says the heads are good, if i pick up that motor can i pull those heads and slap em' on my bottom end with a new head gasket? or is there more to it than that? i'm still learning about engine work, but im pretty mechanicaly inclined, i work in a body shop and have been doing suspension work for years.

thanks in advance, Sean
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Old 03-03-2014, 11:54 AM   #2
sdarc
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Sean, If they are bent then I think you have investigate deeper. Valves only bend when they hit something.
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Old 03-03-2014, 03:35 PM   #3
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still havent got the heads off, not certain that they are bent, just know that air leaks past them i put pressure into cylinders at about 10* before top dead center and rotated the crank to about 10* past, and the intake valves leaked well into the exhaust valves opening up, and cylinder never held pressure..

they could be just worn out of tolerance, its got 192,000 miles and wasnt maintained all that great..
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Old 03-03-2014, 04:24 PM   #4
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Are you sure you were on TDC compression stroke? The 10 degree stuff sounds like you are at TDC exhaust->intake stroke.
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Old 03-03-2014, 04:37 PM   #5
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im not an expert but i would say yes, on the cylinders that wouldnt hold any pressure i would rotate the motor all the way around a few times just to make sure and as the intake valves were closing, they would still leak air until i could hear air hissing out the exhaust.
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Old 03-03-2014, 05:05 PM   #6
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anyways, i think im going to pass on that other motor and just pull mine out and rebuild it..

..this might take a few years, lol

anyone want to help?

..by help i mean stand around and occasionally give a hand..lol
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Old 03-04-2014, 12:41 PM   #7
sdarc
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Sean if you need to borrow a cherry picker and/or engine stands let me know.

Also I'm sure your engine is somewhat toast but when doing a leak down test the engine should be at operating temps.
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Old 03-04-2014, 04:35 PM   #8
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yeah, i know it should be operating temps, but thats hard to get when it doesnt run, lol

i think im going to invest in my own engine stand, seeing that it might sit on one for a year or more, lol

i might hit you up for the cherry picker though..
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Old 03-05-2014, 10:07 AM   #9
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I've got 2 engine stands. You are welcome to one of them.
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Old 03-14-2014, 10:15 PM   #10
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found my problem, no bent valves though, and no contact with the pistons, just overdue for a rebuild..and some oil changes, lol
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