botched crank grind.... too much rod clearnce.

[gusbratz]

how much is too much clearance on a rod? I picked up a B6000 Kubota basket case last summer. It has a little 13HP 2 cyl water cooled diesel (ZL600). http://mountainkubota.com/MTK..EngineSpecsB6000.html
 It looks pretty over engineerd for the power it puts out. I had a bitch of a time finding parts for it but  finally got them from Greece. the crank was way off, out of round and under sized. I took it to a local engine shop along with the undersize bearings mounted in the rods and he sat on it for a month. finally I went to repo it and come to find out he botched it a bit. the one rod came out to .001 clearance but the other is at .007      I figured hey what can you do so the last few days I froze my but off out in the shop putting it all together.  got it running and seems to wok fine plowed snow with it in the driveway for about an hour today. I wonder how long will it last like this........

[dieselgman]

Depends on how hard you run it and whether it can maintain oil pressure or not. What is the hot oil pressure like?

dieselgman

[dieselgman]

You may want to have the crank ground to the next size bearing that is available... to tighten things up. It depends on how much you have invested and how much you wish to rely on the machine.

dieselgman

[gusbratz]

it just has a dummy oil light. it goes out after about 3 cranks of the starter and never comes back on. I was sort of hesitant to put a lot of money into the tractor as I didn't know a lot about it. I had no history on what had happened or if the injection pump was good ect. ect. I sort of rolled the dice and  bought bearings gaskets and pistons,  touched up the valves and put it all together.  I have a bunch of pull start 10hp air cooled diesels I got sort of carried away and bought on sale. I was pretty tempted to try to mount one of them in it.  It would be hard  to do because the tiny little  tractor is built like a real tractor with bellhousing clutch and transmission. not just  a cheesy little v belt driven transmission. Back to the rod question I guess I am just wondering if it will be the difference between a 10,000 hour engine and a 2,500 hour engine or if it will be fairly rapid failure with a rod through the block. I guess time will tell......

[gusbratz]

I do not think so. I tried to listen while I had the tractor running today. Sort of hard to say as it kinda sounds like Kaaa Kaaa Kaaa kaaa any way when it's running. noisy little bugger.  look up that B6000 on youtube and you will see what I mean.

[dieselgman]

Install a test oil pressure gauge... use heavy lube oil. Make up something to use as a stethoscope and listen to the bottom-end noise. If you just have to grind it to the next size, it may be worth the effort to change it out before it takes much damage on that loose journal.

dieselgman

[listard-jp2]

If you just have to grind it to the next size, it may be worth the effort to change it out before it takes much damage on that loose journal.

Quite so, because I am assuming the under size increments on Kubota rod bearings are 0.25 mm (0.010") and with 0.007" already removed, by the time you get just a small amount of ovality on that journal, you may not have enough material left to clean up at the next under size, and consequently end up having to go down another 0.5mm undersize to get the journal to clean up.

You might like to try these people in the UK for your future Kubota spares requirement, as they have dealt with Kubota engines for many years: https://www.jemengines.co.uk/