ok here in a couple of months i plan on rebuilding hte bottom end only of my 4.0 due to the fact that she has 180000 miles on it. i plan on changing rod and main bearing with sealed power bearings (federal mogul) replacing the oil pump with a melling high flow pump, changing the front and rear crank seals with felpro seals, obviously changing the oil pan gasket and doing the oil filter adapter o-ring. should cover it for the next 200k and yes i know im not changing the cam bearings. dont have the time or place to pull the engine out or tear the front clip off for a full rebuild.

there are no issues with the engine still has 20 psi at hot idle stays around 40 when driving. now for the question. last time on my old engine i tried replacing the oil pump with a different brand of oil pump and it was hitting the very bottom of the pan. any suggestions for installing the new melling high volume pump??? also how to replace the front and rear crank seals? the front shouldnt be an issue as ive done plenty of these style seals at work but have never replaced a two piece style seal on the rear.

 

I wouldn't do anything at all to your engine unless it has known serious problems.

Nibbling around on it like you are proposing is going to be a waste of money and time. Been there, done that, got the T-shirt.

When you do rebuild it, just put in a stock spec Melling oil pump. You don't need anything else.

Just my $.02 worth.

 

I agree. I've also heard of those high volume pumps causing the drive under the dizzy to snap. Also gotta massage the oil pan for fitment. Only time I consider a HV Pump is when I do my stroker.

And if nothing is wrong, 180k is barely broken in. My 91 has 208k with perfect oil pressure and no knocks or bangs. She does need some TLC though, like rear main seal, oil pan gasket, etc. nothing major. Just keep her taken care of and that stock drivetrain will last you.

 

At 180,000 miles your engine is still just a baby. I finished my Christmas trip with my '97 and turned over 325,000 original miles towards the end. Unless there's more than what you're saying, don't mess with the engine. Stay aggressive with inspection and preventive maintenance, though.

 

Also jumping on the "DONT MESS WITH IT!" bandwagon. My girl is at 350K now. At your milage it's barely broken in.

Leave it alone.

Change your diff fluids to syn if you want something to do.

 

If it ain't broke don't fix it. Let your ears and oil pressure be your guide.

 

well im a diesel mechanic for a living and am pretty familiar with changing rods and main bearings with no known issues in an engine just as a preventive measure most of the time at 500k which is about halfway through to a rebuild and they are typically worn. took my rods and mains out of my old 4.0 with 190k that dropped oil pressure to 5-7 psi but didnt knock and the bearings were worn out down to the copper but no grooves. decided to replace the engine. just trying to catch problems before they occur. besides the oil pan, front and rear mains are leaking along with the OFA gasket.

ok so ill skip the HV pump and just put a stock melling back in. any suggestions on the two piece rear main seals.

and for the well thats a waste comment: you should just put synthetic in your diffs. i already have.