How hard is it to replace an oil pump?
February 5th, 2020, 02:47 PM
#2
72 Cutlass Ponca City OK
Join Date: Mar 2017
Location: Ponca City, OK
Posts: 155
It is really hard to pull a pan with the engine in the car, and anything that would have resulted or caused an oil pump to fail pretty much necessitates pulling the engine and opening it up.
February 5th, 2020, 02:54 PM
#4
Running On Empty
Join Date: Jul 2018
Location: Earth
Posts: 18,129
I did it on my 71 CS 350 sbo. You need to jack the front of the engine up 4" to negotiate removal of the oil pan. It isn't so bad. What's bad is laying on your back reinstalling a new oil pan gasket after you install the new oil pump but I'd say it isn't a death wish. 
February 5th, 2020, 05:58 PM
#5
Registered User
Join Date: Aug 2011
Posts: 3,022
Are you sure the oil pump is bad? They don't have a high failure rate. Dual exhaust would make it easier, but not easy. Not a difficult engine too pull, it would probably be easier to remove the engine and do a timing chain at the same time IF the pump is the problem.
What are the symptoms?
Good luck!!!
What are the symptoms?
Good luck!!!
February 5th, 2020, 06:59 PM
#6
Registered User
Join Date: Aug 2005
Location: Braceville, Ohio
Posts: 1,972
In your previous post, you mentioned 10 psi oil pressure at hot idle. Changing the oil pump may not help. There's a possibility the oil pump pickup screen may have chunks of nylon from the original nylon timing gear, or not. Bearing clearances, mains, rod and camshaft bearings all contribute. I'd try a step heavier oil if the 10 psi at hot idle brother you. That engine may run fine for thousands of miles. Changing the oil pump in the car is no picnic and may not help. Easy to get leaks also. Small block Olds are cheap and plentiful. Find a replacement, build/rebuilt, when ready switch engines, put yours in a corner for future reference. Jmo.
February 5th, 2020, 08:21 PM
#7
Stock cars are too boring
Thread Starter
Join Date: Oct 2019
Posts: 295
In your previous post, you mentioned 10 psi oil pressure at hot idle. Changing the oil pump may not help. There's a possibility the oil pump pickup screen may have chunks of nylon from the original nylon timing gear, or not. Bearing clearances, mains, rod and camshaft bearings all contribute. I'd try a step heavier oil if the 10 psi at hot idle brother you. That engine may run fine for thousands of miles. Changing the oil pump in the car is no picnic and may not help. Easy to get leaks also. Small block Olds are cheap and plentiful. Find a replacement, build/rebuilt, when ready switch engines, put yours in a corner for future reference. Jmo.
February 6th, 2020, 05:01 AM
#9
Registered User
Join Date: May 2013
Location: Upstate, NY
Posts: 68
You *may* be able to get in there to examine the screen with a boroscope. I had to redo the timing a few years ago on my 5.4-3v F150 when it ate the guides; replaced all lifters, cam followers, guides, chains, phasers, pulled the cams, and couldn't find all the pieces of the broken guides. Pulled the pan off, found the pickup screen caked with plastic. My point is, all that work would have been for naught had I ran the engine without going the extra mile. I couldn't see much of anything with a boroscope, so pulled the pan, and glad I did.
I'm not really of the "run it til it blows" camp; if the oil pressure concerns you, I'd first get a reading with a different gauge (just to rule out the possibility of a faulty gauge), and try the boroscope. You may get lucky and get a clear view of the screen. As stated, it can be done with the engine in the car, but it's much easier out of the car. Back in '13 I started replacing the rod bearings on my 442 with the engine in the car (after jacking the engine and resting the mounts on 4x4 blocks), until I found half the #7 bearing completely gone and the crank journal visibly stepped. The 311 went to the scrap yard at that point.
On the other hand, the 132k mile 2.8 in my '84 GMC has been showing ~5-10 psi at hot idle since at least the '90s, and the engine still runs smooth as a 2.8 can, doesn't make a sound, and runs 40-45 psi cruising. I was concerned at first, but then I stopped caring.
I'm not really of the "run it til it blows" camp; if the oil pressure concerns you, I'd first get a reading with a different gauge (just to rule out the possibility of a faulty gauge), and try the boroscope. You may get lucky and get a clear view of the screen. As stated, it can be done with the engine in the car, but it's much easier out of the car. Back in '13 I started replacing the rod bearings on my 442 with the engine in the car (after jacking the engine and resting the mounts on 4x4 blocks), until I found half the #7 bearing completely gone and the crank journal visibly stepped. The 311 went to the scrap yard at that point.
On the other hand, the 132k mile 2.8 in my '84 GMC has been showing ~5-10 psi at hot idle since at least the '90s, and the engine still runs smooth as a 2.8 can, doesn't make a sound, and runs 40-45 psi cruising. I was concerned at first, but then I stopped caring.
February 6th, 2020, 01:09 PM
#10
Registered User
Join Date: Apr 2014
Posts: 497
If the screen is clogged, oil pressure will dip as RPMs increase.
February 6th, 2020, 01:28 PM
#11
Administrator
Join Date: Oct 2009
Location: Poteau, Ok
Posts: 40,585
When you did the cam work, was the nylon coated timing gear still intact or did it disintegrate into the pan?
February 6th, 2020, 02:16 PM
#12
Registered User
Join Date: May 2013
Location: Upstate, NY
Posts: 68
I didn't mean to imply the GMC had a clogged screen, just pointing out that engine has ran fine for decades on "low" oil pressure. Lots of reasons for "low" oil pressure, and that's a dangerous rabbit hole to go down.
The Olds, however, went 500 miles with the low oil pressure light coming on every time I cam to a stop, but it was also yelling its misery at the same time.
The Olds, however, went 500 miles with the low oil pressure light coming on every time I cam to a stop, but it was also yelling its misery at the same time.
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