Question for RCW

[randyc1]

I have an engine that was evidently ran low on oil. The con rods are trash, and case bearing is scratched. The case cover has the outside land scored badly, the inside is good. Can I machinie the outside land and use the same bearing used in the main case on the flywheel side? I KNow I can put it in there but i guesss what im asking is will it get oil, or has this been done that you know of?

2002 KawMule bought at auction for 526.00......with engine down

[RCW]

Tough question! I presume you are talking about the 620 twin, and are evaluating using the flywheel side main bearing on the crankcase cover side.

The direct answer is no the drive side bearing does not have a thrust bearing surface for the crankshaft, so it will not work.

That said, I would guess you have the skills and tools to machine the case or would not be asking the question.

The issue with replacing the bearing on the cover side is getting the old one out and the new one pressed in and properly aligned without damage to the cover casting itself. It is usually something outside the mechanical abilities, and availability and knowledge of tools for the average owner, and can end up with a cracked or distorted cover even with a skilled machinist doing the work.

A very good press must be used along with the correct dies and real machinists supports to remove the old bearing and press the new one. Use of a Harbor Freight or cheap shop press is a quick trip to disaster! The shop cost to do this easily exceeds the $260 cost of a new case cover with bearing installed.

There is a means to fix the problem of the cover bearing by removing the old bearing and taking it to a commercial bearing house and working through the specifications to locate a bearing with a thrust surface the same thickness, or a thrust bearing adjunct to a new sleeve bearing if you can machine the case cover to create a support surface, then boring your own oil passages in the new sleeve bearing as needed.

Matching the oil seal is not a problem at all as long as you have a good case in which to insert the replacement seal.

The difficulty of this approach is obtaining the exact same crankshaft end play with the proper thrust bearing set up if you do not have the true dimensions available from an undamaged end plate. Kawasaki is not real free with their engine blueprints.

I am not sure what you call the outside and inside land on the case cover. But, if you mean the shoulder on which the case cover bearing rides that is common to the oil seal, you are going to find it far less expensive to just buy the new case cover than to try to repair and machine that shoulder.

If you do not have your own commercial quality milling machine, and because of the thin case castings and cost of all the parts required, not including labor, I recommend you give Beartooth (site sponsor) a call and price a complete new engine.

I have seen a lot of guys tear into these and load up on new parts, only to cut corners by omission and neglect to flush the oil passages, check the cam bearings and valve train for galling from metal particles in the oil, and fail to replace the oil pump, or to check the crankshaft for trueness - it is $80 just to true the crank if you can get a good deal at an engine shop.

Unfortunately they then end up having to purchase a new engine anyway within hours of starting and blowing up the rebuilt version.

Your other option is to shop around for a used engine and trust your luck that it has no coolant leaks and is in good shape.

I do not even rebuild these if there is any case damage or metal in the oil passages. It just costs too much to crank up the machine tools anymore. If I get several cores ahead, I may tie into them and build up a clean engine from parts, but it is only if I have green college kids at the shop working for credit so the labor is free.

[randyc1]

Thats alot of really good information, Thank you for taking the time to explain it so thoroughly. The surface in the case i am referring (that i called a ladn) to is the surface the crank rides in , in the case cover. From the factory there is no bearing in there that i can see, looks like the crank is riding in the aluminum bore in the cover. The inside bore is good and very clean. The outside(close to the seal) is scored. Will it help if i post pics to show you what i am talking about? I understand it is not this way by design. But I have expierience and access to machining equipment. I will be doing the work myself. The oil pump seems ok no metal particles inside it. The Mule is out of a CAT rental store fleet. It was only used on store property and is in good repair. I know I can buy the case new but i was just thinking it will be an improvement to have a bearing in there instead of a steel crank running in an aluminum case. It is a 620E. Bearing part number is 92142. case part number is 49015. The con rods also have no bearings just alumnium rods running on a steel crank like alot of other small engines. I might end up buying a cover new. But i bought the bearing for 3.50 and work is free so it cant hurt to learn from this. Thanks again. will post again soon.

[RCW]

Ok, you have the side cover with no bearing. Some do and some do not. As long as the thrust surface is good, you can machine the housing and install a new bearing to repair the cover bore.

I would double check with a bearing house for the bearing, you will want a bearing with the same coefficient of expansion as the case. Since you have access to real machine tools, I would get one a hair undersized and then align bore the new bearing with the case assembled so you can match to the drive side bearing.

Get a new oil pump and drive gear, even if it looks good. These oil pumps are marginal before they push metal through them, so any wear and you will have valve train problems from low oil pressure.