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12/18/2017 5:13 pm  #1

Kubota D1105-T-E2B

We are working with a Kubota D1105-T-E2B 3 cylinder Diesel engine. The specification for  the bore size of the oversize piston we are fitting is 3.09055" to 3.09129". We finished the bore at about 3.0915" (Service limit is 3.09720"). We figured we had a piston clearance between .0035"-.0004"

The motor ran until it began to work. Temp climbed and it was shut down and disassembled. We found the center piston had picked up. The pistons were sourced from Kumar Bros.. The only info we had to work with was bore size, no piston clearances. I was concerned when the rings needed to be filed about .006" to get specified clearance.

The two end pistons still look good. The owner wants to buy one OE Kubota piston and ring assembly for the center and retry thinking because we are working to Kubota specs it should work fine. I feel we should at least open up the center bore .0005" regardless of what piston we put in. I would not even complain about opening the end cylinders .0005" and the center cylinder .001".

What we did not know when we started this is most of these engines have steam holes. This one is an early one and does not! There do not seem to be any specification differences for with or without steam holes.

Any comments?

Last edited by rcull (12/18/2017 5:16 pm)


2/10/2018 10:50 pm  #2

Re: Kubota D1105-T-E2B

Does this engine have piston cooling jets?? Or piston oilers as they are sometimes called??
While they cool the piston they also provide extra oiling to the skirts.
If you used an aftermarket piston the alloy is an unknown and the expansion rate may be greater then the OE pistons causing the skirts to skuff off.
the OE piston in the center is fine but your idea to go .0005 larger on the skirt clearance is a good one.
If you could drill the steam holes like the new blocks use do it it will do the engine some good in the cooling department or at the very least it won't hurt anything to add them for insurance.

The other issue may be in the cooling system it self. This is an area that is not dealt with during repairs unless its dripping water on the bottom of the rad. The rad should be checked out or replaced if it can't be rod'd out to be sure the tubes are clear which caused the center hole to run hot.

I recently had a customer have me install a bypass tube in a block that was prone to running hot in the center to keep the middle hole from burning up under load may be worth a look at to see if it may cure the center over heat.
In my case it was  5.9 cummins from a loader.

Pro Power Engine & Machine
Victoria BC Canada

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