I have a 1977 F-150 with a 351-M, it seemed to have low oil pressure when the engine was warmed up. It got so bad that the hydraulic lifters started to collapse. I installed a brand new high performance oil pump and ran a heavier weight oil but this bareley made a difference. Finally I decided I had to changed the main bearings. This was a lot easier and cheaper than I had expected! The bearings only cost about $20 and it only took me the better part of an afternoon. The truck runs great now. I highly recommend doing this if you have low oil pressure caused by warn bearings! Good Luck!

 

Could you please outline in a nutshell what you did? I'm assuming that the motor was left in the truck and all you did was drop the pan. Did you drop the crank completely out? How did you deal with where it connects to the tranny?

It just seems like a lot more work than can be done in one afternoon. I'm interested in any shortcuts you'd like to share with us.

Thanks.

Jim

<a href="https://www.ford-trucks.com/pictorial/big/1976_f250_2.html">https://www.ford-trucks.com/pictorial/big/1976_f250_2.html</a>

 

I'm planning on replacing the bearings and oil pump on my 390 for the very same reason. I'm afraid I'll have to pull the engine, though.

 

Hey 390,
It's not going to be this simple for the bearings but for the oil pump, all you've got to do is cut loose the motor mounts and jack up the front of the engine without disconnecting anythng else. Put a 2x4 block between the motor mount and the frame tower, this will give you enough room to drop the pan. Once the pan bolts are out drop the pan to the crossmember, you'll have just enough room to pull the oil pump bolts. Drop the oil pump into the sump and slide the whole show out. When you put it back in make sure the clip on the oil pump driveshaft is up into the bottom of the dist.

Trail Rider

 

Sorry about the delayed reply, my computer was having problems. Once you have the oil pan and pump removed all you have to do is replace the bearings one at a time. First remove the cap, then according to my Haynes Auto Manual you take a cotter pin and bend it so it will fit in the oil passage in the crankshaft. Then you can turn the engine over by hand and it will rotate the pin and push the upper bearing out. This worked very well. You don't have to lower the crank down or anything. I really did get it all done in one day of good hard work. I suggest using a good auto manual. I hope this can help you!

 

That's the first time I've heard of someone changing out the main bearings that way. I always thought that the bearings were really stuck in there and really hard to get out.

The best thing is that you don't invest a lot of time.

Thanks.

Jim
'76 F-250 4X4
<a href="https://www.ford-trucks.com/pictorial/big/1976_f250_2.html">https://www.ford-trucks.com/pictorial/big/1976_f250_2.html</a>

 

I just have one question... How did you go about finding the right over-size bearings? Or did you just use stock sized?

I have the same problem now, and the pan is going to be dropped for a new oil pump and to put the drive shaft back in so I can put the distributor back in. I'd like to get this done at the same time! Hope you come back to read this! thanks!

 

Guys, this method of bearing replacement is nothing new. This procedure is used on big over-the-road trucks when they get an "in-frame" overhaul (engine overhauled without removal from the truck) and on marine diesel engines as well.

Chris - the bearing size ("STD" or amount undersize) is usually stamped into the back side (steel backing side) of the bearing insert. If the bearing has a Ford part number, it should be standard size. Undersize bearings are usually marked with 010 for .010" U/S (undersize), 020 for .020" U/S, etc... Newer FM and Clevite bearings have the info put on with an inkstamp, and I don't know how long that holds up after it has been installed.

Some words of caution for all: be sure the "tabs" of the bearing inserts are aligned properly in the block and caps. Also, be sure to properly install the caps into the proper positions (arrows and numbers) and torque the bolts correctly. A friend of mine thoroughly destroyed a 1969 big block trying to "fix" it!

I also swear by HV oil pumps - Melling makes a great product.

 

I know about bearing sizing.. I was just wondering what size bearings Dill used and how he came to the conclusion to use that size bearing. My question was simply if he used over-sized bearings, what size and why? Or did he use standard sized?

<<Chris - the bearing size ("STD" or amount undersize) is usually stamped into the back side (steel
backing side) of the bearing insert. If the bearing has a Ford part number, it should be standard size.
Undersize bearings are usually marked with 010 for .010" U/S (undersize), 020 for .020" U/S, etc...
Newer FM and Clevite bearings have the info put on with an inkstamp, and I don't know how long that
holds up after it has been installed.>>

 

If the crank is standard (not ground undersize), it might be possible to get .001" U/S bearings to make up for crankshaft journal wear. Ford had selective fit bearings when they originally built the engines.

To determine if you need .001" U/S bearings, it requires either:
1.) removal of the crank to "mike" it (then it's no longer a "roll-in repair"), or
2.) installing a standard set of bearings, measuring the clearance with plastigauge, and if too much clearance, locating a set of .001" U/S bearings.

 

i just got done doing this in truck overhaul. afew thing that i found is that this way of doing it is cheaper but watch out for the proverbial can -o- worms! i started with pulling my tranny to change the front seal. ended up changing out the main and rod bearings, oil pump (mellings h.v.) the timing chain and the water pump and front and rear main seals. here is some thoughts to help you out.
1. read and highlight all your torque specs in your manual!!!
2. remove the radiator and front sway bar. this gives you so much more room.
3. i used a hoist to lift the engine to get the pan out and in. it makes it easier, just to lift it a couple of inches.
4. when doing the mains start with the thrust bearing first, the middle bearing and make sure you have it seated right.
5. USE PLENTY OF ASSEMBLY LUBE!!!!!!!
6. replace one bearing at time and ensure you inspect each journal as you go.
7. after you torque one main spin the engine with a socket and breaker bar.( nothing would suck more to get them all in and find it binding up and having to go through them all again)
8. when you change your oil pump, clean the pick-up tube good!!! i used acetone, it work great.
9. when replaceing the pick up on the oil pump. remember the correct postition of the p.u., you won't get the oil pan back on if it is wrong. oppps!
10. Take your time and have a buddy help who knows alittle about engines.( you will find out who your true friends are after this.)

final note, if i had to do it again i would just pull the engine and rebuild or get another engine rebuild it and replace.
but if the cash flow is low this "red-neck rebuild" works. i only spent about $180.00 including oil and water pump timing chain, bearings, belts, plugs, valve cover gaskets. fuel pump block off plate. oil gaskets, front/ rear main seals, tranny seals,..tranny filter and oil and engine oil and filter and other misc stuff......if i get another 100k out of the engine, then it was worth it.

dad77 f250 2wd custom 400m