how bad is bad, what happens when oil pumps wear? |
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how bad is bad, what happens when oil pumps wear? |
worn |
Jun 4 2020, 10:40 AM
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#1
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can't remember Group: Members Posts: 3,156 Joined: 3-June 11 From: Madison, WI Member No.: 13,152 Region Association: Upper MidWest |
I am rebuilding a 911 engine for which metal parts went into the oil pump. The impellers and case show some scoring and I will probably be replaced. Still it begs the question: how bad can it be? The scoring between impellers can be honed flat to prevent more galling. The scores between the impeller edges and the case obviously will allow oil to leak past. To that I ask - so what? I can readily imagine a reduction in output and therefore oil pressure. On the other hand it is hard to imagine a really dramatic reduction in pressure due to oil leaking past/through some scratches.
Do scratches tend to propagate wear in the pump? When oil pumps fail, how do they fail. Thanks folks, and note I am not asking whether or not to replace a pump, I am asking what happens when you don't. Or how bad does it have to be before it matters. |
sixnotfour |
Jun 4 2020, 12:19 PM
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#2
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914 Wizard Group: Members Posts: 10,433 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains |
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worn |
Jun 4 2020, 06:21 PM
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#3
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can't remember Group: Members Posts: 3,156 Joined: 3-June 11 From: Madison, WI Member No.: 13,152 Region Association: Upper MidWest |
Which may be the wAy I go, but doesn’t answer my question. Thanks though. |
porschetub |
Jun 5 2020, 12:47 AM
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#4
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Advanced Member Group: Members Posts: 4,701 Joined: 25-July 15 From: New Zealand Member No.: 18,995 Region Association: None |
Which may be the wAy I go, but doesn’t answer my question. Thanks though. Did you "run" a cam due to a blocked cam oiler tube ?. Damage to the gears and pump body will result in reduced function of the pump on both pressure and return (scavenge) sides,the return side is less important but once the oil heats up you may well find the pressure side is delivering less oil pressure @ hot idle. Also there will be a delayed time before the system primes due to oil leaking past the gears which IMO is caused by wear/damage to the pump body and not the gears. Good luck. |
worn |
Jun 5 2020, 08:52 AM
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#5
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can't remember Group: Members Posts: 3,156 Joined: 3-June 11 From: Madison, WI Member No.: 13,152 Region Association: Upper MidWest |
[/quote]
Did you "run" a cam due to a blocked cam oiler tube ?. [/quote] Well, no. I was really stupid. The nut came off of #1 intake rocker and jammed between the case and a cam lobe. The timing pin sheared through the cog teeth as the cam came to a halt. #2 & 3 pistons have valve imprints. That nut is going to cost me about $5000. Dumb dumb dumb. Because of course I was the one who didn't tighten it enough. It was on a hot day in Montana, and I didn't respond to the change in engine sound properly. New pumps are over $1,000, so I am trying to avoid that. |
stownsen914 |
Jun 5 2020, 02:44 PM
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#6
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Senior Member Group: Members Posts: 913 Joined: 3-October 06 From: Ossining, NY Member No.: 6,985 Region Association: None |
Good used early 911 oil pumps can be had for $100-200
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