casper7.3
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- May 19, 2011
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Hey all, I've got a weird one here and need some help!
A little background.
My buddy just bought this 1996 with about 275k miles. Oil cooler O-rings were leaking and the IPR was sticking. We replaced the O-rings, IPR, and changed oil. He drove home (about 25 miles) and when he came to a stop he noticed the oil pressure gauge flicker. He then shifted from drive to park and the gauge went to nothing for a second or so, then came back up to normal..
What we have checked/replaced/verified so far.
Hooked up a manual gauge to the hpop reservoir. hot idle there is ~10 psi in park. Shift to drive, idle goes up a bit, pressure stays the same. Now for the weird part. When you shift back to park, the rpm's drop by about 150 (~660 to ~510) and the pressure goes down to 5psi then back up to 8-10 psi. It will do this every time with the engine at operating temp. Hpop reservoir is always full.
Also checked pressure at engine block test port on left rear by oil filter. It reads the same.
Checked bypass valve in oil cooler housing, since we were just there figured maybe trash. still the same.
Replaced the check ball and spring in engine block below the hpop. Still the same.
Tried another new IPR.
No computer codes.
I just can't understand why the problem happens shifting from drive to park and also why the rpm's drop from drive to park. Normally its the other way around.
My buddy said it was fine when he picked it up from the other owner and drove it to me.
Any Idea's??
Thanks!!
A little background.
My buddy just bought this 1996 with about 275k miles. Oil cooler O-rings were leaking and the IPR was sticking. We replaced the O-rings, IPR, and changed oil. He drove home (about 25 miles) and when he came to a stop he noticed the oil pressure gauge flicker. He then shifted from drive to park and the gauge went to nothing for a second or so, then came back up to normal..
What we have checked/replaced/verified so far.
Hooked up a manual gauge to the hpop reservoir. hot idle there is ~10 psi in park. Shift to drive, idle goes up a bit, pressure stays the same. Now for the weird part. When you shift back to park, the rpm's drop by about 150 (~660 to ~510) and the pressure goes down to 5psi then back up to 8-10 psi. It will do this every time with the engine at operating temp. Hpop reservoir is always full.
Also checked pressure at engine block test port on left rear by oil filter. It reads the same.
Checked bypass valve in oil cooler housing, since we were just there figured maybe trash. still the same.
Replaced the check ball and spring in engine block below the hpop. Still the same.
Tried another new IPR.
No computer codes.
I just can't understand why the problem happens shifting from drive to park and also why the rpm's drop from drive to park. Normally its the other way around.
My buddy said it was fine when he picked it up from the other owner and drove it to me.
Any Idea's??
Thanks!!
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