Main Bearings

kaw550 · Jan 6, 2013

I took off the bearing cap between the 3rd and 4th row of pistons.

Sould there be any signs of wear?

Mountain Ram · Jan 6, 2013

I think that motor is ready for a rebuild...

When I tore down my '96 Explorer donor motor with over 100k on it- there was nothing like that...

kaw550 · Jan 6, 2013

The engine runs pretty good. I only drive a few hundred miles a year. Can I just drop in a new set of bearings and a timing chain? Should I just put it back in as is?

RIbronco · Jan 6, 2013

It looks like the cap was shifted, the wear should cover about 2/3 of the bearing surface, and be centered on the shell.

You can go cheap, and just replace the bearings, but if the main and rod journals are out of round, the new bearings will have accelerated wear vs having everything in specification.

Broncobowsher · Jan 6, 2013

At this point the minimum you should do is a set of bearings. Putting it back together with that much wear is not a good idea. What else is worn out? Find out when a full rebuild is done. But right now we know the bearings are bad. they are an easy change at this point, the uppers spin in easy enough you don't even have to take the crank out.

Look at the rod bearings too.

The copper is the mid layer of metal in the bearings. If it goes any further it will be into the steel backing plate, that will destroy the crank and you will be doing a rebuild and getting the crank ground or replaced. This was caught just before it got really bad.

Mountain Ram · Jan 6, 2013

RIbronco said:
It looks like the cap was shifted, the wear should cover about 2/3 of the bearing surface, and be centered on the shell.
.

The machine shop that did the bore for my 347 builds a lot of 302s... A lot of Mustangs around here. Anyway- he insisted on checking the line bore just because of this situation. He said Ford 302/5.0 blocks are notorious for shifting line bore. This bearing is not on true center of the crank, so it is wearing uneven. As said above- you will experience quicker wear on new bearings, but you need to drop new ones in.

Todd

73azbronco · Jan 6, 2013

thats actually considered normal wear, they wear that way do to dynamics of the rotating assembly, I would not go crazy thinking the crank is out of alignment just yet. Bigger isse is the bearing is worn out and does need to be replaced. That will teach you never to pull a motor apart thats working

http://www.studebaker-info.org/tech/Bearings/CL77-3-402.pdf

My68Br0nc0 · Jan 6, 2013

Thrown some main bearing and rod bearings in and call it good!

Pa PITT · Jan 6, 2013

how many mile are on those bearings.. And since you said that you only put a few hundred miles a year on it .. Then Yes just put in a set of rods & main bearing a be done with it. I'd only do the T/C if it's stock or plastic . But if it's a metal roller then I'd not replace it.
.. No problem in my years at my parts story . I sold a mountain of overhaul kits and I've seen lots of bearing look like that. and the replacement worked find.
.. No Problem you'll be fine.

kaw550 · Jan 6, 2013

73azbronco said:
That will teach you never to pull a motor apart thats working

All this for a freeze plug.

I went out and checked a rod bearing. Less wear but less than perfect.
How long does an oil pump usually last?

No idea how many miles are on the engine. It was remanufactured so I am a little surprised but I guess the engine could have been installed any time in the last 40 years.

Should I pull the heads and check the cylinders before I order parts??? If so, do I need to replace the head bolts?

Master Chief · Jan 6, 2013

I had to rebuild a reman. 2.8 in an '85 Bronco II after running it for about 3,000 miles. Thing was overheating, machine shop said it was not their problem. Instead of arguing about it, I pulled it back out and did my own overhaul. Found that they never touched the heads, 3 bad exhaust valves. It must have had the old rings on it.

I've rebuilt probably 30 engines over the years, thought I would save time this way. All it taught me was do them myself.

TBS-POPS · Jan 6, 2013

Head bolts do not get replaced they are reusable unless stretched. If you pull the heads you might as well rebuild the whole thing seeing as its apart.

broncosbybart · Jan 6, 2013

My 2 cents would be to do a timing chain (along with crank seals) while it is apart as well as a new oil pump. I like the high volume oil pumps that vary pressure from about 20 psi at idle to 60psi wide open, vs the stock type which seem to always push around 40psi. You can check the cylinders from the bottom to see what they look like. I wouldn't worry about pulling the top end off of it to check it. If it does have badly scored cylinder walls, time for a complete rebuild, heads and all...

nvrstuk · Jan 6, 2013

Save your hard earned $$$$and replace the brgs and button it up!! IF in10 yrs after putting 3,000 miles on IT THEN rebuild it.....

kaw550 · Jan 7, 2013

Can I just reorder the stock size? From what I can tell they are the the standard size. I pulled one half of each to get the numbers. I googled MB2121P and CB634P. It looks like they are standard size but I could not find what the other number mean.

Main Bearing:
Clevite 77
12 88
MB 2121P
LOWER E

Rod Bearing:
Clevite 77
6 88
CB634P
A

Broncobowsher · Jan 7, 2013

If it was undersized it would be marked. Those are standard size.

broncodriver99 · Jan 7, 2013

I just did the same thing. Pickep up a 2000 explorer engine for a couple hunded bucks. Several of the mains and rods were showing copper at a supposed 75,000 miles. Granted it didn't look like the oil had been changed too often. Cylinder crosshatch looked good. Threw a set of main and rod bearings, oil pump, timing chain, and crank seals in it and buttoned it up. Havent put it in yet but figure it will buy me a couple years until I need to do a rebuild.

Pa PITT · Jan 7, 2013

Like someone else said.. Save your hard earned bucks and just put in the bearings ..
. With only 500 miles a year you'll never wear it out. Timing chain is no harder to change several years from now . And much cheaper later .

red hot71 · Jan 7, 2013

I bet if you never opened it up and didn't run it low on oil or over heated it, probley would of gone 20-30K before any other problems would of arose, enless it already smokes.

Main Bearings

Bronco Guru

Attachments

Recovering Masshole

Bronco Guru

Sr. Member

Total hack

Recovering Masshole

Bronco Guru

New Member

Bronco Guru

Bronco Guru

Attachments

Bronco Guru

Bronco Guru

Bronco Guru

Just a Bronco driver for over 50 yrs!

Bronco Guru

Total hack

Bronco Guru

Bronco Guru

Sr. Member

Similar threads