Brown truck - 78 F150 351m 4x4 C6


So it looks like I'll be replacing the main and con-rod bearings this weekend, and I think I'm comfortable with the process...

• Pull the headers to get them out of the way
• Pull the dist cap and wires as an assembly
• pull the plugs
• raise the engine
• drop the pan
• pull the oil pump, pickup and filter

And then for the real fun:

1. Pull one con-rod cap at a time
2. put tubing over the bolt threads
3. pull the bearings out - check for wear
4. clean up the crank - degrease with carb cleaner
5. clean up the con-rod and cap - degrease with carb cleaner
6. install the upper bearing
7. install the lower bearing into the cap
8. put plastigage on the lower bearing surface, perpendicular to the cap
9. install and torque the cap
10. remove and check the plastigage
11. if everything is in spec, re-assemble with assembly lube

Assuming all looks good, and I re-install the bearings for real:


how much lube goes on the bearing and where?


The Chilton manual says cover the bearing in oil, but other sources say lube only the bearing face, not the back.


Although the crank can be rotated to distribute the lube from the bottom bearing to the top bearing, I'd think it'd be better to install the top bearing with (at least some) lube on the bearing face. This, of course should be easier on the con-rods than the mains, but the principle remains.


I would think that it would be bad to get oil/lube on the back, and it should only be on the front


Same question for main bearings.


The Chilton also says 0.0008-0.0015 clearance on the bearings, 40-45 ft/lbs on the con-rods, and 95-105 ft/lbs for the mains.


Thanks in advance for your great ideas, answers and support!

 

Sounds a little tight for clearance on the mains but if that's what it calls for go with it. You're right about not putting anything on the backside of the bearing. Make sure you use something that doesn't let any lint or anything behind or your clearance won't be right.

I like to use a straight 30 weight oil to lube the bearing and crank. I like the cheapest stuff out there it seems nice and thick it stays where you put it. I think the last stuff I used was made by Warren lol.

 

You're on the right track.
If you do rods first, then do mains, any abrasives or dirt that get into the crank journal oil passages at the mains could wash back into your new rod bearings.
Backside of the bearing needs to be clean.
You can't put too much assembly lube on IMO.
You shouldn't get much play to work on the mains, timing chain holds it in front, flywheel/flexplate holds rear. It will be tighter than the rods.
Don't get carried away pushing pistons back into cylinders, there are still some valves open up there somewhere.
Use brass hammer if required to get rod caps to loosen, don't booger rod bolt threads.
Have mechanical oil pressure gauge on hand when you start up. You could even prime the oil system before you stab the distributor.
Just pulled the pan on my 79 with headers. Didn't need to pull anything, but the plates for the motor mounts did clip the edges of the oilpan. Easy enough to get off but won't be able to go back like that without killing the gasket surface.
What if all goes well and when you pull the last cap you find a gouged up journal? I'd pull them, check them, and snug them back up until it was their turn before I went farther.

 

To each his own but I've just wiped crank journals with a clean rag, no carb cleaner. On the mains it helps to roll the uppers out & in if all cap bolts are loosened a turn or so to lower the crank. Tap the caps loose with the brass hammer mentioned above. Don't re-torque until all (main) bearings are replaced; start with the center main.


AND - give us updates.

 

Mine is a '77 F150 4x4 351M and I never touched the exhaust or motor mounts or distributor nor raised the engine. I believe yours is the same under the front.
I "maybe" removed the plugs but I don't recall. It was November 1992. It will make it easier to turn that "low compression optioned" 351M over with a socket on the snout bolt.

I just jacked the truck up in front, set some good stands under the frame at the radius rod mount area, removed the pan hard rod from the frame bracket and tied it down near the axle .... and removed the pan and a main and rod bearing and went to see what size they were. I did have some HD stands .... on concrete ..... but the axle hung from the shocks .... but I could get under it.

I returned with standard bearings and a new HV oil pump and gaskets and I didn't loosen any caps until I was working on that main. I started at front and did all 5 mains one at a time, I did put half a rear main seal in that cap .... and torgued each cap as I put it back together. All the upper shells just pushed out with a nudge from an old shell .... they will only come out on the tang side.

I felt journals for smoothness with a fingernail ..... and lightly polished with abrasive strips, cleaned with solvent on a strip of cloth, oiled, and put together. Turning the crank as you go helps gain access.

As for oil, I used a few squirts with an oil can on the journal ... but none on the backside of the insert. The insert's back and the surface of the rod or block or cap was wiped dry.

I then did the rods. Front to rear .... in order. Just barely bump rod up from crank after pulling the cap, shells slip right out.

 

I've gotten a lot of practice turning the engine by the front bolt, and it's not pleasant. I think pulling the plugs will be a necessity.

Last time I had the pan off, before the headers, I think I just raised the frame and let the drivetrain sag. Seems like that created enough room to get the pan out. I'll try that before further, possibly unnecessary, disassembly.

I figured con-rod bearings first, cuz they're higher than the mains, but sounds like y'all recommend mains first. So it will be!

Thanks for the advice so far. Keep it coming, cuz I'll need all the help I can get! UPS bringing packages tomorrow...

 

"Rod bearings 1st because they're higher than the mains"; rotate the crank until the rod journals are down, much easier to get at. As you remove the bearings look closely at each for unusual wear, gouges, etc. Gives an idea of what to look for on the journal.


I started with the rods, only because they out number the mains & get that done 1st. But, it's like, does one start eating toast or bacon 1st?


Earlier post I meant start re-torqueing on the center main, so you lift the crank evenly back in place. And 30w oil in a squirt can sounds good. When you reach the finish line expect to have it in your hair, running down your arms, etcetc. Much fun!


For this job is there a need to remove dist cap & wires?

 

I was also thinking con-rods first, because it seems like you'd be getting them out of the way. But I'm not married to that idea.

I included cap and wires because many sources say to pull the distributor and plugs. I understand pulling the plugs, as it should make the crank easier to rotate. I don't really understand the need to pull the distributor as I can easily install the oil pump driveshaft from the bottom.

 

I think it's more of a safety thing, but I could be wrong.... Happens all the time.

 

I've done this a few times in the past and never pulled the distributor, to be honest, it never occurred to me, but I really don't see the need either.

 

Agreed, lost my mind for a minute...


I see no reason to pull the distributor. I was thinking that pulling the cap could be a safety thing, much like disconnecting the battery.

 

I'd rather not pull the distributor, but I was thinking about using a drill to spin the oil pump before firing-up the engine.

 

Papa please post lots of pictures of your work - I've never done this and would like to see how it's done. Thanks.

 

I just pump oil in top of the oil pump .... turn drive a few rounds, and when near full, add gasket and bolt it in place engaging the pump drive shaft.

If you want to just turn the engine over for a prime after buttoned up, oil pan filled, etc .... before putting spark plugs back in, just go to starter solenoid and cross between the two larger studs and the starter will turn the engine very fast with the plugs out ... and since the keys are not even in the ignition .... no start.

 

You might be surprised at the torque required to spin just the oil pump. It's true that you could turn the motor over to spin the oil pump, but actuating only the oil pump makes sure everything is wet before anything rolls over. That being said, you're going to turn things over a couple if times just to get access to the rod bolts.
Also, (and I'm a little rusty on this), I believe there's a retainer ring that goes around the oil pump drive shaft, but I don't recall if it's above or below a passage that only allows the rod to be installed from one direction. I've got a 351m pan off now, I'll get a picture up soon.