Slow Speed Diesel Engines > Other Slow Speed Diesels

Kubota EA300

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Tanman:
I picked up a EA300 for $300, tore into it today and found that one of the valves wiggles a fair amount and the valve seat has worn a little. I have the manuals and part numbers. It seems like parts are a little tough to find, is my best shot my local Kubota dealer hunting some valves and valve guides for me?

guest18:
That might be your best bet. Kubota should be able to get them. While you have it apart it would be a good time to check the cylinder bore and if itís within spec hone the cylinder and re-ring the engine.

Just in case the bore is out of spec. There is an oversized piston and rings available.

Which guide is worn?

Do you have any idea of the hours on the engine?

Henry

guest18:
Tanman, Just received a call from a friend in Jacksonville Florida that runs a shop that makes compact diesel generators for sailboats. They use Kubota engines only.

He knows the EA300 and EA330 very well. The company made Hundreds of units with those engines.
We talked about your situation and he explained to me that itís normally the exhaust valve guide that will get some wear over time. The intake valve guide normally donít give any problems but since the engine does not have valve guide seals there is a possibility of having oil sucked around the intake guide if itís very worn. This situation can be made worse with oil getting past the piston rings and if the air cleaner is restricted. He said there has been a few known cases of runaway engines but very rare.

He mentioned to replace valve guides, check valve stems and seats for wear, check cylinder and re-ring it and make sure the breather is functioning properly.

He mentioned that a good machine shop should clean up the seats. However the heads are known for rusting through on salt water applications so if it was a salt water engine check out the head thoroughly. If the head is bad a new one is available but itís around $500.00.

When I was visiting him years ago I saw a whole bunch of EA300 heads on a table that were just rebuilt. I ask him about those and his response was the market pretty much dried up. At times they good ones on eBay for rebuilding.

Henry

Tanman:
Thank you very much Henry, I have just ordered the parts you suggested! I will need to have the valve seats cleaned up for sure. No salt water damage but some damage from the loose valve. Thank you for the information, it helped me out a lot!

Question for folks with more experience, Iíve only replaced piston rings once on a 2-stroke four wheeler and havenít de-glazed a cylinder before. Should I give it a go or have a shop do it?

snowman18:

--- Quote from: Tanman on March 10, 2020, 03:03:13 AM ---Thank you very much Henry, I have just ordered the parts you suggested! I will need to have the valve seats cleaned up for sure. No salt water damage but some damage from the loose valve. Thank you for the information, it helped me out a lot!

Question for folks with more experience, Iíve only replaced piston rings once on a 2-stroke four wheeler and havenít de-glazed a cylinder before. Should I give it a go or have a shop do it?

--- End quote ---

if you have chrome moly rings I would let the shop do the work.

Read the full article, https://www.hastingspistonrings.com/tech-tips-faqs/cylinder-bore-refinishing

Cylinder bore refinishing is extremely important in the engine rebuild process. There are some basic rules and facts that will prevent common problems incurred when deglazing or refinishing cylinders.
Cross Hatch Angles

The correct angle for cross hatch lines to intersect is approximately 45 degrees. Too steep an angle promotes oil migration down the cylinder resulting in a thin oil film, which can cause ring and cylinder scuffling.

Too flat a cross hatch angle can hold excess oil which conversely causes thicker oil films, which the piston rings will ride up on or hydroplane. Excessive oil consumption will result.

The diagrams will illustrate cross hatch angles.

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