Full Size Jeep Network

So my 87 has a nasty tick I couldn't seem to figure out.

Since my 90 GW caught fire if pulled engine and tore it down and found it's in really good shape.
The plane is to throw rod and main bearings in it along with new cam and freshen up the heads, and throw it in the 87.



Sent from my SM-N920V using Tapatalk

Might as well replace the cam bearings, too. I'd also pull/inspect the pistons, replace the rings, and throw a quick hone on the cylinders while you're in there. New oil pump gears and a mid-late would help, too.

Sent from my HTC One M9 using Tapatalk

I would skip the mains, and look critically at the rod bearings before replacing them. They will go a long time if in-spec and given good oil pressure. You could, if you want, buy a crank kit which is a new crank and properly sized bearings. You still should check the clearances as you put it together, but a kit should be about the same cost as the individual bearings.

Yep, cam bearings are immediately suspect. Delaminating cam bearings are a known problem with these engines, which will lead to low oil pressure and its associated problems.

JMO - a running, seasoned engine with good oil pressure and compression has a lot going for it. "Throw" sounds a bit flip - I would not have disassembled this engine without assessing its condition, and I would probably use it without a major disassemble ... depending on compression and oil pressure. Why throw away the remaining service life in a good engine?

That said, the old-fashioned overhaul is rings, rod bearings and valve job. Not done so much any more, but this is what's usually meant by "freshen up." The main expense of a rebuild is the oversize pistons and labor to fit them. If you don't replace the pistons, the rings will wear out faster than with straight bores, and you must use inexpensive iron rings, so they are sure to seat.

tgreese wrote: JMO - a running, seasoned engine with good oil pressure and compression has a lot going for it. "Throw" sounds a bit flip - I would not have disassembled this engine without assessing its condition, and I would probably use it without a major disassemble ... depending on compression and oil pressure. Why throw away the remaining service life in a good engine?

x2, a little homework goes a long way to prevent waste of $$$

I looked at everything. Cam bearings are beautiful, crank looks sexy still, cylinders are slightly glazed .
Now that being said the main bearings and rod bearings are showing enough wear to replace. Piston skirts are still tight to the cylinders so re honing and reringing ... I am doing a head job with a 6 angle valve grind. I'm not porting or polishing heads.

As far as "assessing" engine before disassembly the jeep was my daily till it caught fire (electrical). 70psi cold oil pressure to 15- 20psi oil pressure when warm (170*) at idle, under load 1500-2000 rpm oil pressure was 40-45psi. Compression was about 115-120 cold dry test, although it smoked due to valve stem seal leaks, guides will be checked during head job.

Sent from my SM-N920V using Tapatalk

Ok so when I was pulling the rear main seal out of the block a piece of the block broke.... How big a deal is this?

Sent from my SM-N920V using Tapatalk

hmm since that a part of the rear main seal id wonder if it would leak now.. Id Probly tack weld that back on.. Heat it up with a torch and weld that broken tip back on

Hmmm maybe

Sent from my SM-N920V using Tapatalk

Man, that's a tough question. It seems like such a small little thing, but it would really suck to put all that time and energy into building the motor just to have a chronic rear main leak. In your shoes, I'd toss it. I'm over cast iron 90° V-8s as it is, so I wouldn't spend money and effort on an iffy one.

Just weld it back on. It isnt the end of the world on that little peice.. I gatuntee itll leak if you dont.

. Heat with a torch until water turns into a mist or sizzles instantly when you put water on ( not red hot fyi dont wanna warp it but cast need preheated before you weld).. have someone hold the broken peice with some needle nose pliers as you do it.. Heat both peices together.. Weld it on with a low to medium wire speed just use little tacks so you dont glob the weld.. If you glob it take a little file and file it down carefully. Wiggle it with your fingers after it cools to make sure its solid and itll be good as new... Also dont let it cool down too fast or itll crystallize and form little cracks in the welding.. Let is cool down gradually with a torch on and off on and off

We do this on the cast iron ZJ knuckles.. The brake pads slide on the knuckles and over decades it wears small grooves in the knuckle.. Causing the pads to stick in place.. Heat the sucker up weld in the groove.. file it down and good as new.

Just go slow and be carefull.. Cover up all the bearing surfaces to keep splatter off.

A thin section of oil soaked cast iron? I wouldn't even try to weld the old piece in place. Maybe build it up by TIG brazing but I doubt it would hold.

Uses a rope seal, right? Maybe if you offset the joint into the cap a little on that side?

The engine kit came with a 2 pc reinforced rubber seal.

Sent from my SM-N920V using Tapatalk

SJTD wrote:A thin section of oil soaked cast iron? I wouldn't even try to weld the old piece in place. Maybe build it up by TIG brazing but I doubt it would hold.

Uses a rope seal, right? Maybe if you offset the joint into the cap a little on that side?

Oil doesnt Spread in flames instantly like gasoline lol. If youre that worried use brake cleaner all over that sectiin and itll be clean.

The very worst is oil would catch fire on the preheated area or the area that was welded but its not like the entire engine would spontaniusly combust

But to weld you need the area clean of oil anyway.. So use brake cleaner all over the rear main seal section

Not worried about fire lol.

Cheapthrills wrote:The engine kit came with a 2 pc reinforced rubber seal.

Sent from my SM-N920V using Tapatalk

Don't you install those seals with the joint offset from the cap joint anyway? And the damage is on the wet side of the seal...

As we say in the rocket business: "Prolly be alright"

Thank you for the input you guys...

Fire bad mmmmmkay

Sent from my SM-N920V using Tapatalk

SJTD wrote:Not worried about fire lol.

engine Oil ignites around 500f.. And it needs to stay that hot for long periods of time like an exhaust manifold would.. Ive seen engine oil catch on fire and fizzle out seconds later from welding.

Just brake clean the oil off the rear of that block and cover everything else and itll be fine. The welds needed for this pinky nail tip chip would only be tack welds for a second.


If this were my block it would be welded already... Just clesn the thing.. get a couple cans of brake clean..

Boy that's a bummer/tough one. If it was mine I'd drag it down to machine shop and ask their opinion.
Unless you get it perfect you may have problems with rear main bearing cap/bearing clearance.
If it is off, even by .001 it will screw with bearing clearance.
If the bearing cap is off, clearance will be off, could have bigger issue than an oil leaker.

Yea it sucks... but here is where I'm at, this engine is supposed to be temporary anyways 1-2 years to do another swap... so looking at it I'm gonna continue with assembly MacGyver the issue area and drive it... if it doesn't work, it doesn't work. And I'll start thinking about the next move.

Thanks for all of your input
I'll try the things suggested see what seems to turn out the best.

Sent from my SM-N920V using Tapatalk

babywag wrote:Boy that's a bummer/tough one. If it was mine I'd drag it down to machine shop and ask their opinion.
Unless you get it perfect you may have problems with rear main bearing cap/bearing clearance.
If it is off, even by .001 it will screw with bearing clearance.
If the bearing cap is off, clearance will be off, could have bigger issue than an oil leaker.

Yea i was thinking that if welded on itd have to 100% flush for the cap. But it should be. As long as person holding it on keeps the chipped peice flush with where it cracked