my '89 YJ (vin T) is finally leaking oil from the rear main seal at an undrivable rate. i have been told by many that it is worth the extra money to buy the rear main seal and a 1 piece oil pan gasket from the dealer so monday i will be picking it up. i have also been told that on a high milage engine, it is good practice to replace the oil pump with a high volume one. i have never replaced an oil pump before and was looking for some guidance or a link to a step by step removal/install. if someone could also tell me everything i might need that would be fantastic(ie screen assembly, pump, screen tool?). someone reccomended the "melling" high volume oil pump from quadratec and a new screen assembly? i have also even heard you should weld the screen assembly tube to the pump...i am a full time tig welder so thats not very difficult, but is it neccesary?

any input would be much appreciated.

If you're not having any oil pressure problems I wouldnt mess with the pump. These 258's run forever.
Josh

i dont know what my oil pressure should be. when i first start it(its 10 degree weather in MA right now), the pressure is around 55psi. once it is good and warmed up it hangs around 13-20psi even on the highway. i know the inside of my motor is pretty sludgy as i recently replaced my valve cover gasket and inspected the cover. i am positive i will at least need to replace the screen. at the moment it is still my daily driver and it is extremely cold outside(and thus in my garage also) so i do not want to do this job twice. if replacing my oil pump is a raging pain in the ass and could easily destroy my engine then i will let it slide. if it is a simple job but the parts are kind of pricy, i'll do it anyway for the piece of mind.

1)could someone explain the steps involved

2) what parts are recomended(high volume, brand, tools, etc)

3)should the screen tube be tacked to the pump assembly?

First things first!! Most excessive rear main seal leaks are caused by BLOWBY! If the pcv is partially or completely clogged the pressure cannot get into the intake system and instead pushes oil out the seal!! First thing to do is to clean all the crankcase vent tubing and replace the pcv with a new one.
ONLY then should one be thinking about repairing the leak.
I always use a stock oil pump, the high volume ones are for much higher rpm and stress than our little engines will ever see..
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

that could have been the initial cause prior to my ownership, however immediately after purchasing the vehicle i swapped in an MC2100 and thus removed, replaced, or rerouted every vacuum line in the vehicle. the rear port on the valve cover has a fram breather that is routed to the underside of the air cleaner. the front port on the valve cover has a pcv valve which is routed to pcv port on the rear base of the carburetor.

But as for my oil pump question...

so you believe a high volume oil pump is not necessary regardless of milage? that works for me

what about tackwelding the pickup tube to the pump? have you heard of this/is it a good idea?

is pump replacement straight forward or are there any possible snags?

I have braised/welded many of them and drilled/tapped and inserted a lock bolt in many others.
The area in question is a pressure fit and is not trusted by hotrodders! I have never seen them come apart but have heard stories of dragsters going dry from dropping a pickup.
So I always take some measures to make my head feel better... the factory simply presses them on there and they seem to last forever.
Once more... take the pcv off and clean out the hose and go get a new one... Then take the back hose off and do the same.
On Wranglers with similiar blowby I put both hoses to a vac source.. So far it has stoped all blowby leaking problems.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />