Oil Pump replacement 89 1500 4.3

[SphinxMunkey]

Well, I just bought a truck, it's got a slight knock in the bottom end at idle and it gets 0-3ish? psi when it's warmed up, cold it's got 60+ so I believe it's the pump not the bearings. (however I'd rather start with the 20$ part instead of the 100$ part anyway)

The truck is the 4.3 vortec in a 89 K1500 5spd with 190-200k on it and it runs and drives fine otherwise.

The question, is does the oil pan come out without pulling the engine, and if so HOW... because I think I'm going to have to pull at least the oil filter assembly off of it to get the pan free... It's already unbolted and everything, but the bolt on the passenger side transmission brace looks to be the wrong damn way and hits the oil pan and won't come out, leaving the pan wedged in there and no room to turn to get by the filter assembly on the other side...

Thanks for any responses, I'd like someone with prior knowledge of doing it IE. trying and what happened LOL

[2000CAYukon]

Originally Posted by SphinxMunkey

Well, I just bought a truck, it's got a slight knock in the bottom end at idle and it gets 0-3ish? psi when it's warmed up, cold it's got 60+ so I believe it's the pump not the bearings. (however I'd rather start with the 20$ part instead of the 100$ part anyway)

The truck is the 4.3 vortec in a 89 K1500 5spd with 190-200k on it and it runs and drives fine otherwise.

The question, is does the oil pan come out without pulling the engine, and if so HOW... because I think I'm going to have to pull at least the oil filter assembly off of it to get the pan free... It's already unbolted and everything, but the bolt on the passenger side transmission brace looks to be the wrong damn way and hits the oil pan and won't come out, leaving the pan wedged in there and no room to turn to get by the filter assembly on the other side...

Thanks for any responses, I'd like someone with prior knowledge of doing it IE. trying and what happened LOL

I have not done this on the 4.3; however, I have removed the pan on my 90 GMC K1500 to replace the pan gasket. I used a cherry picker (engine hoist) to lift the engine high enough to remove the pan. The dist and fan shroud needed to be removed. The motor mount pins and oil cooler lines also needed to be removed.

In your case, you should use a mechanical gauge to verify pressure before doing this. I also doubt this is an oil pump issue itself. Oil pump failure is not very common. The pickup can become clogged especially in the old days when they used a nylon coated cam gears. If you are going to remove the oil pan, you should check all of the rod bearings along with the oil pickup screen.

//2000CAYukon

[SphinxMunkey]

Originally Posted by 2000CAYukon

The pickup can become clogged especially in the old days when they used a nylon coated cam gears. If you are going to remove the oil pan, you should check all of the rod bearings along with the oil pickup screen.

//2000CAYukon

I wanted to start on the low $ end, however in the back of my mind I'm thinking it's the bearings but I don't want it to be, I was planning to check the clearances and the screen before/as I put the new pump in.

Hopefully cleaning out the pickup and putting a new pump in it will fix the problems, I know it's not the sensor because it runs and drives fine with no noise and when it warms up (which is why I think it's likely the bearings) it has 0ish oil pressure and develops a little knock. I tried 15-40 oil and a new filter to see if it would help, which it slightly did, but not when warmed up.

Main questionI think the oil pan will drop out without removing/lifting the engine any, but I want someone thats done it or at least tried it before to give me input...

Thanks for the response, keep em coming guys.

[2000CAYukon]

I am sure someone from this forum has done this on the 4.3. On the 5.7, there was no way to get the pan out without lifting the engine.

It sure sounds like bearings but I hope I am wrong.

Good luck.

//2000CAYukon

[SphinxMunkey]

OK, so good news. And for future search information.

M40 torx head bolts (2) hold the oil filter assembly on. It'll drop right out.

If you wiggle the oil pan around some, and tilt it, the bass ackwards bolt that comes out toward the oil pan that holds the transmission brace on the passenger side of the compartment will barely slip out and then the oil pan can drop right out.

Would have taken 20 minutes if I could have just done it yesterday instead of had g/f time

[2000CAYukon]

How did the oil pickup screen look? Can you feel play in any of the rod bearing?

//2000CAYukon

[SphinxMunkey]

I took one of the main caps and rod caps off and they look decent, not worn excessively or anything of the nature, scarred or anything. I didn't feel any play at all in any of the rods I checked but I'll likely check again tomorrow afternoon/night when I get home.

The pickup screen is clean and clear, I am semi baffled and think that the spring may have gotten weak in the pump? or the cam bearings are bad, seeing as I was searching yahoo again and found that to be rather common? Maybe a bypass/drain back valve is stuck/broken/open or something? I don't know.

Thanks for the help and any input you may now have -Josh

[SphinxMunkey]

OK, I looked at the bearings again, normal picture of worn out bearings, rubbed the coating off and they are mostly down to the brass looking metal.

Thanks for the input along the way, Take care.