Rod Bearing Condition on 240 Utility

Sun Nov 23, 2008 4:45 pm

I'm in the process of removing the pistons from my 240 utility to replace the rings, and just got my first look at the rod bearing. As you can see in the image of the bottom shell, copper (or bronze) is showing thru in certain areas. The top halfs show all copper. There are wear streaks along the surface, but they are smooth and there are no rough or spalled areas. They are factory originals, marked on the back IH Std, with a part number.

Am I correct in assuming they are bronze inside and because the outer plating has worn away they should be replaced? I was going to do a Plastigage test, but when I got a look at them I thought I shouldn't bother and just get new bearings. The main bearing shells look the same way.
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I'd appreciate any advice and suggestions
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Re: Rod Bearing Condition on 240 Utility

Sun Nov 23, 2008 6:19 pm

I always plastigage bearings when I disassemble engines. In this case it may not tell you very much.

You will have to micrometer the bearing journals.

Re: Rod Bearing Condition on 240 Utility

Mon Nov 24, 2008 10:33 am

Mic. the crank,---make sure it's still round, and see if it falls within the correct readings, then go from there,---might have to have the crank reground, by a machine shop. thanks; sonny

P.S. the colors you are seeing are a well worn bearing shell, with a lot of clearance---lots of oil pressure escaping around these instead of going up higher to the other internal parts.

Re: Rod Bearing Condition on 240 Utility

Mon Nov 24, 2008 12:13 pm

Thanks for the responses. I just didn't know where the copper color was coming from, or what it meant. I'm going to borrow a set of micrometers to check the tolerances. I just discovered a wandering scratch on the center main's surface, so I'm real concerned I may have to pull the crankshaft. With a loader on the tractor, splitting the tractor is something I was really hoping would not be necessary.

Re: Rod Bearing Condition on 240 Utility

Mon Nov 24, 2008 3:49 pm

I just didn't know where the copper color was coming from, or what it meant.

I just discovered a wandering scratch on the center main's surface.


Bearings are made in layers. The outer layer, bearing surface, is very soft material, usually something similiar to babbitt, and normally a silver color. Next layer is something harder yet will bond to the steel backing and babbitt type material. In this case some material similiar to a copper alloy.

Now the important stuff. Minor scratches on bearing journals. A lot is going to depend on the size of the scratch, how many, and a lot of experience. You can take a slip stone to smooth up the scratch ridges. Slip stone = very very fine grit sharpening stone. Or 2000 grit emery paper/cloth.

Re: Rod Bearing Condition on 240 Utility

Tue Nov 25, 2008 7:33 am

Haven't miked the crank yet. So far I've been doing everything from underneath. I removed the pistons, and discovered two broken oil rings, which explains the oil burning problem. The upper rod bearing shells are more worn than the bottoms, showing all copper on the bearing surfaces. Pulled the main bearing cap, and it looks the same way. The crank journals look fine. I'm concerned about the crank main journal.

Here's the big question. I've only looked at the center crank main so far. I discovered a number of o.5 to 1 inch long smooth longitudinal scratches that I can feel with my fingernail. However, there is also a damaged circle in the center, opposite where there was a port in the lower main bearing shell. The surface is damaged at that point. Assuming inspection of the front and rear mains don't show anything worse, what are the consequences of putting new bearings in, and leaving the crankshaft the way it is? The tractor has a loader on it, and splitting will be a major job that I'd rather not undertake unless I have no choice. I'd like to do it right, but then again I realize I probably only will use the tractor, as a loader, 40 hours a year.

I'd sure appreciate some advice and experience.
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Re: Rod Bearing Condition on 240 Utility

Tue Nov 25, 2008 8:59 am

The center crank main so far. I discovered a number of o.5 to 1 inch long smooth longitudinal scratches that I can feel with my fingernail. However, there is also a damaged circle in the center

Assuming inspection of the front and rear mains don't show anything worse, what are the consequences of putting new bearings in, and leaving the crankshaft the way it is?

The longitudinal scratches on journals are a problem. Not common. The circular marks or scratches are much more common and if not to severe or numerous are not a problem. I'm thinking there is something worn other than severe engine wear.

If you can feel the scratches with your fingernail - I would take the crank to the machine shop for work. Perhaps a polish or to get turned down.

The longitudinal scratches will rapidly eat up a bearing.

Re: Rod Bearing Condition on 240 Utility

Tue Nov 25, 2008 9:18 am

Eugene

Thanks for the reply. I didn't describe it right. By "longitudinal" I meant circular . . . along the circumference of the bearing surface, not across it.

I'll report back after I get a look at the front and back mains

Paul

Re: Rod Bearing Condition on 240 Utility

Tue Nov 25, 2008 10:22 am

Your oil port will make the dark place around the center of the crank.---If you are not going to put many hours per year or going to enter the local "full pull" contest,---then I to would just slap in a new set of rings, rods, and mains and run it.---I have a 404 that I need to do the same thing with,----oil going right up the muffler and spraying in my face, fouls plugs in 30 mins. or less, etc! thanks; sonny

Re: Rod Bearing Condition on 240 Utility

Tue Nov 25, 2008 3:37 pm

If anyone has been in the motor and you don't know it's history, check to make sure all the rod and main caps are in the right place. I've found engines over the years with the numbered rod caps mismatched on rods (this usually doesn't last long, can get ugly real quick!), and one with the main caps swapped as well. I think you said the bearings were marked as standard, so I'm hoping the motor is original; but as others have said, make sure you measure the crank, people don't always put the right size bearing back in!

If the motor was still original with that kind of copper showing, I guess you didn't have much oil pressure registering? You haven't mentioned the oil pump... Make sure you check the bottom plate on the pump. It usually warps allowing the gasket to blow out between the bolts and you loose significant oil volume right at the source. If it's not bad you can true it up on a belt sander, otherwise have it milled or replace it.
Stan.

Re: Rod Bearing Condition on 240 Utility

Tue Nov 25, 2008 6:46 pm

Excellent points Stan!!! I have a 504 that the oil pump plate must have come loose on and it spun a rod!---not sure if the crank is even grindable, looks really bad!---Engine was locked to th point of the rod being welded to the crank! (teens driving it and thought the red oil light on the dash meant go faster)---Owner didn't want to mess with the tractor any more so I ended up with it! thanks; sonny

Re: Rod Bearing Condition on 240 Utility

Tue Nov 25, 2008 9:47 pm

Thanks for the suggestions.

As far as I can tell, the motor is original. The cranks and caps are stamped with the cylinder numbers, and everything is in the correct place. The bearings are all stamped with IH part numbers, and labelled "Std". I miked the rod journals today, and everything was within factory spec, with no more than 0.003 between 0 and 90 measurements. That was a relief! All of the rod bearing's surfaces are showing copper, the top shells 100%, the bottoms maybe 30-50%. I pulled all of the main caps, and the main bearing surfaces are also showing alot of copper, including the thrust bearing in the rear. I'm going to put new "Standard" size bearings in both the rods and the mains. Don't think I should go undersize since the journals are in spec.

Any suggestions on removing the main top shells with the crank in place?

I haven't taken the oil pump apart, but from your comments it sounds like I should. When I bought the tractor, it was only running on 3 cylinders because of a frozen valve with associated bent push rods. When I dropped the oil pan, I discovered the oil pickup screen was really clogged up, and the valve rocker area was very dry . I assume the valve froze due to insufficient oil getting to the top. I had the head rebuilt, and cleaned the screen, and it pumps lots of oil now, but I never did get a good oil pressure measurement. The dash gauge reads about half scale but I suppose that doesn't mean much. Sounds like taking the pump apart for a good cleaning may be a good idea, and I'll check the plate while I'm at it.

I went into the engine because after having the head redone, it began spraying droplets of oil out the exhaust stack like an old locomotive, all over the tractor and myself. Cars were slowing down to see where the fire was. Ended up finding two broken oil rings. Here's a piston . . . I never saw an oil ring like these. Will the new ones be the same design?

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Re: Rod Bearing Condition on 240 Utility

Tue Nov 25, 2008 10:13 pm

New rings are all a 3 piece design now days on everything I have been into!--I see your piston is an IH---noticed the logo on the bottom!---looks like high dome too!

plugged oil screen probably took out the bearings, and would have stuck the valves in the head!---really check out that oil pump good!!!!

If you drop the main caps, you might be able to "roll" the top halves into place! the rear main oil seal is another story!!!---hope yours dont leak too bad!--on some of them the flywheel has to come off to get to a retainer to replace them,---but if yours isnt leaking too much, don't worry about replacing it for no more hours than you intend to use it! thanks; sonny

Re: Rod Bearing Condition on 240 Utility

Tue Nov 25, 2008 10:33 pm

Any suggestions on removing the main top shells with the crank in place?

I discovered the oil pickup screen was really clogged up, and the valve rocker area was very dry . I assume the valve froze due to insufficient oil getting to the top.
Loosen the main bearing caps just a bit. Only remove the one you are working on. You can use a flexible item like a thin plastic putty knife to push out the top half of the bearing. Or nail (head must be thinner than the bearing half), cut to length, insert into oil hole, rotate the crank shaft away from the tang/tab. Actually the top half usually comes out easily.

Replace both halves of the bearing, oiled and snug up, not tight. If you are going to plastigage either no oil or a very light machine oil.

My guess on the rocker arm area is lack of oil pressure due to excessive clearance in the bearing journals.

Rear main seal - depends on style. You can replace the wick type seal, if its accessible from the crankcase. I would replace it.

Re: Rod Bearing Condition on 240 Utility

Wed Nov 26, 2008 7:16 am

Eugene, SONNY, and Stan

Thank you for all of the help and suggestions. Sure is great to be able to have friends with experience looking over your shoulder!

The nail sounds like a great idea for getting the upper main shells out. Could you explain how the main bearing clearance affects the oil pressure? I've heard that before, but never understood it?

I'd love to replace the rear oil seal, but I don't think it can be done without splitting the tractor. The front one also looks like it's leaking. If I didn't have a loader on the tractor I might do a lot more.

Want to see something really ugly? Here's what I saw the first time I removed the rocker cover:
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Guess I'd better take the oil pump apart, clean and check it out, just in case,
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