Oil pump for a first timer

ebougher622

New Member
Original poster
Joined
Apr 15, 2024
Messages
3
Location
12578
Hey fellow jeepers, first time owning a 98 TJ so bare with me. I need to replace my oil pump any tips or tricks for someone who's never had to do this before?
 
The biggest issue is removing the cats and oil pan. Once you get there the oil pump is easy. There’s no need for a high volume oil pump. You’ll need a new Fel-Pro gasket for the oil pan. How’s you RMS? You’ll be there, so if it’s leaking you might as well replace it. You’ll need anaerobic sealant for that. The Fel-Pro RMS comes with a little tool to keep it from tearing when you slide it into the groove on the block. When you do the oil pan make sure and add RTV at the appropriate locations indicated in the FSM. Be careful not to over torque the bolts on the front of the oil pan. They are threading into aluminum. When you reinstall the cats put anti-seize on those four bolts.
 
Last edited:
The biggest issue is removing the cats and oil pan. Once you get there the oil pump is easy. You’ll need a new Fel-Pro gasket for the oil pan. How’s you RMS? You’ll be there, so if it’s leaking you might as well replace it. You’ll need anaerobic sealant for that. The Fel-Pro RMS comes with a little tool to keep it from tearing when you slide it into the groove on the block. When you do the oil pan make sure and add RTV at the appropriate locations indicated in the FSM. Be careful not to over torque the bolts on the front of the oil pan. They are threading into aluminum. When you reinstall the cats put anti-seize on those four bolts.

Awesome thank you so much for the info I really do appreciate it.
 
Awesome thank you so much for the info I really do appreciate it.

Also, there’s no benefit to a high volume oil pump in our 4.0L engines. Good luck!
 
You'll likely find instructions in the box about priming the pump before you start the jeep. I spent a LONG time trying to prime mine but I never could get it done. So I fired up the jeep and IMMEDIATELY had pressure. No idea if this is the typical experience or what, just heads up.

Related to priming, you'll end up needing to remove your distributor. To put it back in you'll need to know what you're doing, by which I mean finding TDC or doing it "the easy way." I have a write up for the easy way in the How To section.
 
  • Like
Reactions: MikeE024
Hey fellow jeepers, first time owning a 98 TJ so bare with me. I need to replace my oil pump any tips or tricks for someone who's never had to do this before?

I’d also replace the pickup tube…my tube was sitting super loosely in the old pump when it should have been a tight fit.

It’s not a fun time without the expensive tool due to the bends in the tube, but I got it in by using a dead blow, wrenches, and stacked wood blocks.

I believe my Melling pump builds oil pressure faster on startup than the previous pump did based on the lack of noises and less occurrences of lifter tick on start-up. Sure glad I didn’t change the lifters before I did the pump or while I had things open.
 
Last edited:
You'll likely find instructions in the box about priming the pump before you start the jeep. I spent a LONG time trying to prime mine but I never could get it done. So I fired up the jeep and IMMEDIATELY had pressure. No idea if this is the typical experience or what, just heads up.

Related to priming, you'll end up needing to remove your distributor. To put it back in you'll need to know what you're doing, by which I mean finding TDC or doing it "the easy way." I have a write up for the easy way in the How To section.

awesome thank you for the info :)
 
I’d also replace the pickup tube…my tube was sitting super loosely in the old pump when it should have been a tight fit.

It’s not a fun time without the expensive tool due to the bends in the tube, but I got it in by using a dead blow, wrenches, and stacked wood blocks.

I believe my Melling pump builds oil pressure faster on startup than the previous previously did based on the lack of noises and less occurrences lifter tick on start-up. Sure glad I didn’t change the lifters before I did the pump or while I had it open.

Here’s the photo of how I “pressed in” the tube.

The blocks under my leg are acting as spacers to allow leverage on the wrench which is placed over the flare. Smack down on the wrench in green to press it in. My leg kept the wrench in place. My right foot w/ wood blocks kept the pump from moving on me.

I started off with the wrench on my leg since it was similar in height to the flare…wood blocks work better lol. I wished I had the tool while trying to figure out how to do this, but then all was good 20 minutes later and I moved on with life.

IMG_3176.jpeg
 
Last edited:
You'll likely find instructions in the box about priming the pump before you start the jeep. I spent a LONG time trying to prime mine but I never could get it done. So I fired up the jeep and IMMEDIATELY had pressure. No idea if this is the typical experience or what, just heads up.

Related to priming, you'll end up needing to remove your distributor. To put it back in you'll need to know what you're doing, by which I mean finding TDC or doing it "the easy way." I have a write up for the easy way in the How To section.

Wish I could help with this, but I think things are different in my vehicle.

In my 2005, I removed the OPDA and made a long flat-head bit out of some round bar so I could turn the pump using a drill. How do you guys prime the pump on the 04 and earlier models?

Glad you had pressure right away @hear it’s hard to beat that.
 
Wish I could help with this, but I think things are different in my vehicle.

In my 2005, I removed the OPDA and made a long flat-head bit out of some round bar so I could turn the pump using a drill. How do you guys prime the pump on the 04 and earlier models?

Glad you had pressure right away @hear it’s hard to beat that.

nope, exactly the same process.
 
  • Like
Reactions: MikeE024
Now I’m curious, what makes you think your pump wasn’t primed?

Maybe mine wasn't either lol. 😳

Every thread you'll read on this topic talks about how it will spin easy and then once it primes it will suddenly get much firmer. I never felt the tiniest hint of a change.
 
  • Like
Reactions: MikeE024