Oil Pump - any reason not to change it? (1 Viewer)

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Columbia, SC
Still in the process of rebuilding the front drivetrain and water pump/timing belt on the 99 LC. While tearing it all down noticed a lot of oil/dirt/sludge all over the oil pans and front. Wasn't enough to be dripping and no signs of leak on the ground, but enough crud underneath to make me want to find the culprit(s). After a lot of looking and not being able to pinpoint single source, decided to just fix everything while I was there. So besides everything for the timing belt/water pump, I pulled the cam and crank seals, oil cooler/filter bracket assembly, and both oil pans. After getting it all apart looks upper pan gasket was leaking and possibly crank seal.

So at this point I'm cleaning everything up and looking at this oil pump. The only item still left before I could just take out the 8 bolts holding it is the oil pump strainer. A quick search for parts and a new OEM Aisin is $68 at RockAuto - not exactly a high price for a critical part.

So all this said - is there any reason to not just go ahead and change it? What I mean is the factory manual makes it sound like hardest part is getting the sealant on right and torquing the bolts - is it really that simple at this point? And are there any reasons I'm not thinking of why putting a new one on is not a good idea?

The way i look at it this way I would eliminate any leaks they may be coming from it and oil pressure should be back to factory new.

As always appreciate feedback - Scott
 
What did you decide to do on the oil pump replacement? I'm about to dig into the timing belt, water pump, etc and was wondering the same thing and a search on here found your thread. No one has answered you which is odd...
 
I think no one answered because almost no one ever "has" to change it. Apparently they never fail. For me, I went ahead and did it. Not because of oil pressures, but to fix oil leaks. When I got the truck it had been doing a lot of sitting the previous couple years and the form in place gasket around the oil pump, oil pans, etc had dried out and oil was seeping from several areas.
I personally didn't think it was that hard to change, but remember that I already had the front differential off the truck. If you don't drop the front diff and the frame cross member you can't get the oil pans off. And you can't change the pump without removing both upper and lower oil pans due to the oil strainer tube.
Unless it is leaking like mine was I probably wouldn't mess with it. FSM says first thing to do when changing the oil pump is pull the engine, which probably is easier than taking apart the entire front drivetrain. Let me know if you need further details.
 
I think no one answered because almost no one ever "has" to change it. Apparently they never fail. For me, I went ahead and did it. Not because of oil pressures, but to fix oil leaks. When I got the truck it had been doing a lot of sitting the previous couple years and the form in place gasket around the oil pump, oil pans, etc had dried out and oil was seeping from several areas.
I personally didn't think it was that hard to change, but remember that I already had the front differential off the truck. If you don't drop the front diff and the frame cross member you can't get the oil pans off. And you can't change the pump without removing both upper and lower oil pans due to the oil strainer tube.
Unless it is leaking like mine was I probably wouldn't mess with it. FSM says first thing to do when changing the oil pump is pull the engine, which probably is easier than taking apart the entire front drivetrain. Let me know if you need further details.
Okay, that's what I was thinking when I took a quick look under there last night. Pretty tough, if not impossible, to change with out doing what you did or pulling the engine... no wonder no one on here has done it. I'll leave it alone. Thanks, Clay
 
I've replaced a couple of these engines (with used salvage yard engines) and have always pulled the oil pans ... I was wondering how you did it with the engine in the truck.... but I have also inspected the removed engines for why they failed and what was worn @300k and actually saw very little wear and the oil pumps were never an issue... if that gives you any peace of mind...
 
I've replaced a couple of these engines (with used salvage yard engines) and have always pulled the oil pans ... I was wondering how you did it with the engine in the truck.... but I have also inspected the removed engines for why they failed and what was worn @300k and actually saw very little wear and the oil pumps were never an issue... if that gives you any peace of mind...

What did you find at 300k?
 
at 305k i measured very little end play in the crank... saw no sign of blow by, the bores still had the cross hatch hone marks, rods looked good on both ends no signs of excessive heat or wear, the only reason the 305k engine died was due to a radiator failure that caused it to over heat and blow a head gasket... was easier to put a 100k engine vs fix the 300k one
 
Is there any updated wisdom on this over the past 7 years?

I have an engine with 195k miles on a stand and trying to service anything I might want to before installing it. Right now I am considering pulling the pans to do the RMS and O-Ring and debating about replacing the oil pump and O-Ring at the same time. I did not notice any leaking when I looked last, but I will need to double check. Appreciate any suggestions.
 
if someone was at point where both pans were down and rear main retainer was off I don't see a good reason to not remove the front and reseal it while doing the front crank seal. The you can replace that O ring also.
resealing the upper pan without resealing the front and rear retainers isn't logical. Unless maybe the thing is still installed in the LC
Follow the book and measure the actual oil pump. It's probably fine. Just a reseal, the Oring and the crank seal.
 

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