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Kohler: Need an opinion on my Crankshaft Journals

Well, after a wedding and much fussing around, I finally got my L600 pulled apart. As soon as I got the crankshaft out, I headed for the bench. wiped everything off and starting checking the journals with a micrometer.

First of all, everything mikes as standard per the book. However, due to some scoring the three mains will definitely need grinding to an undersize. My question is about the rod journals........they mike standard and so close to round it isn't funny. After measuring it several times, the most deviation I can find is less than one thousandth........perhaps a half thousandth or so (if that), with no discernible taper. The surfaces are quite good compared to the mains and I think a good polish will suffice, then install standard size bearings. I have to admit, I've never seen this before. Rod journals are ALWAYS "egg" shaped on every engine I've ever worked on. I know it's kind of difficult to analyze without pictures, but I'd like to get some input from those who've been there before. If I'm taking an unnecessary chance, I'll get them ground also.......just means locating and buying more bearings.

Another question, about gaskets. I can make just about any gasket for this engine, but there is one at the rear of the engine that is strange. It covers the rear main assembly and has (or had) two "ears" that fit in pockets of the crank case. The ears appear to be some kind of thick felt I think. If this particular gasket is available I'll buy it. If not, I'll have to "imagineer" something.
 

Vanman

Subscriber
Last Subscription Date
06/10/2020
About "just locating and buying more bearings". Make sure you have them in your hand before committing to undersized. It's a crying shame, but they're a little hard to come by. There's a nice fellow on here who's a sponsor and has a stash of them. My memory is terrible, but I believe it's @Partsman

These engines are massive for the amount of work they do, and run nice and slow. Only a couple hp per cylinder! This may explain why you're not seeing the usual rod journal wear. Not sure why the rods would look great, and the mains be worn badly. Odd.

I have a crank that *really* needs to have rods and mains turned. It's like double the maximum clearance! Looks like it ran with the oil pick up screen severely clogged, presumably with sludge... The bores are as much as 15 thou over. And yes, they're still standard at the top. :crazy:

Keith
 
I have a sneaking suspicion that the oil gallery feeding the mains might have been partially clogged........plus the goop I took out of the crankcase was about the consistency of thin peanut butter. Still doesn't explain why the rod bearings were still pretty good though. The main journals have scoring in line with the oil holes on all three....the outside of them actually looks pretty good.

You're right about having the bearings in hand........I'll contact Partsman and see what he's got. If he's got some oversize rod bearings I'll probably bite the bullet and just do them all.

I pulled all four pistons/rods out and found nothing horrible, but it'll be a couple more days before I get a chance to check the cylinders for taper, etc. Actually, for the number of hours probably on this engine, it's still in pretty good shape from what I can see. Worn, yes...but nothing really tragic. A bit of a relief from some of the stuff I've brought back to life!

Keith, about your crank....I had a model T Ford engine with a badly scored crank and the shop completely welded/ground all the journals. Came out nice. I don't remember the cost, but it was less than $200............a LOT cheaper than a new, modern crank at $1300!
 

Zephyr7

Registered
The main journals have scoring in line with the oil holes on all three....the outside of them actually looks pretty good.
That kinda sounds like maybe there was some sediment in the oil at some point? A little grain of grit can jam on the edge of the hole and scribe a line until it gets ground up and freed.

Bill
 
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Charley K

Subscriber
Last Subscription Date
10/09/2019
Well, after a wedding and much fussing around, I finally got my L600 pulled apart. As soon as I got the crankshaft out, I headed for the bench. wiped everything off and starting checking the journals with a micrometer.

First of all, everything mikes as standard per the book. However, due to some scoring the three mains will definitely need grinding to an undersize. My question is about the rod journals........they mike standard and so close to round it isn't funny. After measuring it several times, the most deviation I can find is less than one thousandth........perhaps a half thousandth or so (if that), with no discernible taper. The surfaces are quite good compared to the mains and I think a good polish will suffice, then install standard size bearings. I have to admit, I've never seen this before. Rod journals are ALWAYS "egg" shaped on every engine I've ever worked on. I know it's kind of difficult to analyze without pictures, but I'd like to get some input from those who've been there before. If I'm taking an unnecessary chance, I'll get them ground also.......just means locating and buying more bearings.

Another question, about gaskets. I can make just about any gasket for this engine, but there is one at the rear of the engine that is strange. It covers the rear main assembly and has (or had) two "ears" that fit in pockets of the crank case. The ears appear to be some kind of thick felt I think. If this particular gasket is available I'll buy it. If not, I'll have to "imagineer" something.
Hi, I have measured hundreds of crank journals, I can't remember ever seeing an egg shaped rod journal as I can remember. Maybe a ten thousandth or so but nothing that would require a regrind. Sure, if there was an oil failure, but not on a normal tear down. Maybe I'm missing something here but normally its uniform wear.
 

nblack

Registered
concur with Keith again. The bearings are AWFULLY hard to find for a L600. I think that they were disco'd a few years back. Someone who knows better might correct me, but that is my memory. Did I mention expensive? Oh, yeah.. they are that too. Maybe some enterprising person on the 'Stak could whip us up a batch of babbitized refurbs, so we could keep going to the next millenia?
 

gdstew

Registered
"Not sure why the rods would look great, and the mains be worn badly. Odd"

B & S factory guy explained it like this-----Dirt/grit in the oil will embed into the softer material ( aluminum rod or bearing ) and scrape into the harder material ( steel journal).
In the small engine business I saw hundreds of worn out crank journals. Most of the times you didn't even need to measure them.
 
concur with Keith again. The bearings are AWFULLY hard to find for a L600. I think that they were disco'd a few years back. Someone who knows better might correct me, but that is my memory. Did I mention expensive? Oh, yeah.. they are that too. Maybe some enterprising person on the 'Stak could whip us up a batch of babbitized refurbs, so we could keep going to the next millenia?
I've wondered about re-babbitting old shells also, and I think there are a couple of outfits out there capable of such work. Sure would be nice if you could send in "your tired, your weak, your worn" (apologies to Lady Liberty) and just get them relined.

Edit: By golly I found one! Unfortunately, it's in India but it does show that such a service exists.......http://www.lubroglide.com/Products/White%20Metal%20Lining/White_Metal_lining.htm
 
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nblack

Registered
Maybe that will become my "duty" at some point. I have an, er, "penchant" for the old Hercules ZXB's, and they have (what I think) an ingenious system on their rods. They are babbited, and then they have shims that you pull out as they wear. Brilliant!
 
Maybe that will become my "duty" at some point. I have an, er, "penchant" for the old Hercules ZXB's, and they have (what I think) an ingenious system on their rods. They are babbited, and then they have shims that you pull out as they wear. Brilliant!
Just like a model T, so any fool (like me) can adjust. Actually, I scored some NOS Kohler bearings but they're all standard so it looks like the crank is going to get chrome plated then ground back to standard.......not cheap.......ouch. From what I've seen the rest of the engine looks pretty good, and that brings up something else.........

All three main bearing surfaces look good, that is, even color and no scratches or damage. The journals on the crank definitely have scratches and scoring though.......world's toughest babbitt?
 
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