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Oil Pump Diagram

Fishtaco

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Sep 29, 2020
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Perth AU
Is there an oil pump O ring problem that can let the oil drain down if left sitting?

I am chasing a dry start that I have had since purchase, I only get it if the TJ sits for more than a day.

No other engine noise problems apart from the dry start rattle even with a really expensive guaranteed no drain back filter.

Thanks :)
 

Irun

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Oct 31, 2019
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Is there an oil pump O ring problem that can let the oil drain down if left sitting?

I am chasing a dry start that I have had since purchase, I only get it if the TJ sits for more than a day.

No other engine noise problems apart from the dry start rattle even with a really expensive guaranteed no drain back filter.

Thanks :)
There's no O-ring I remember seeing. There is however a gasket between the pump and pickup tube. Those are held together with two bolts. How many miles do you have on the engine?
 

SkylinesSuck

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Mar 28, 2020
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Northern VA
There is a gasket between the pump and the block, and that's it. The pickup is an interference fit into the pump body and is pressed in, then secured with a bolt as Irun mentioned. As far as I know the oil does drain back out of the pickup when the engine stops as designed. I think your "dry start" issue is something else like a lifter on its way out.
 

Irun

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It's rare to have an oil pump issue. However, they can wear or fail, especially if the pickup gets clogged. Have you pulled the pan to verify that there are no obstructions?
 
OP
Fishtaco

Fishtaco

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There is a gasket between the pump and the block, and that's it. The pickup is an interference fit into the pump body and is pressed in, then secured with a bolt as Irun mentioned. As far as I know the oil does drain back out of the pickup when the engine stops as designed. I think your "dry start" issue is something else like a lifter on its way out.
So it only happens if left standing for over 24 hrs, to me it sort of sounds like a timing chain rattle but the TJ doesn't have a hydraulic chain tensioner.
 
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Fishtaco

Fishtaco

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Sep 29, 2020
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It's rare to have an oil pump issue. However, they can wear or fail, especially if the pickup gets clogged. Have you pulled the pan to verify that there are no obstructions?
Not as yet because it runs like a heart beat apart from the quick dry start rattle
 

JKP

TJ Enthusiast
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Aug 20, 2020
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Warner Robins GA
Leaky ADBV or leaky lifters are the most likely suspects.

And I have the original lifters in my 92 with nearly 300K mi, and my 06 with 235K mi and they don't leak down...
 

Irun

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As @JKP said, I'd be looking at lifters next. Pulling the valve cover and checking for a collapsed lifter, after it sits for a day or two, is way easier than pulling the oil pan.
 

SkylinesSuck

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Mar 28, 2020
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Northern VA
It's not the worst thing in the world, but compared to many many other motors (that don't require pulling the head) it's harder. I feel 2-3 hours is kinda optimistic too. But maybe I just work slowly 😆
 

Irun

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2-3 hours if you have the parts, gasket and coolent on hand when you start and you can even mill the head while it's off if you wanted to.
Kind of depends where you are. Rusted, and broken, bolts turns this job into 2 - 3 days. Ask me how I know! :mad:
 

01CuHed

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Apr 28, 2018
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South/Southwest
Fishtaco since winter has now returned I'm experiencing my seasonal 2 second "cold dry start rattle" that ONLY happens during winter. Any other time my 2001 4.0L never makes a tick even after sitting for days?
 
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Fishtaco

Fishtaco

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Sep 29, 2020
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Perth AU
Fishtaco since winter has now returned I'm experiencing my seasonal 2 second "cold dry start rattle" that ONLY happens during winter. Any other time my 2001 4.0L never makes a tick even after sitting for days?
Its over 100 here on the other side of the world :) I get it summer or winter but only if it sits for at least 24 hours and it only happens sometimes.