You were lucky. Cracks into the seat pocket will result in a loss of press fit and a dropped seat. A bent rod and piston are about the best you can hope for after that.
Blowing white smoke
- Thread starter Bonaro
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RCW
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Equipment
BX2360, FEL, MMM, BX2750D snowblower. 1953 Minneapolis Moline ZAU
Bonaro - look up Lance - "007Kubotaguy" here on OTT. Send him private message.
Lance has quite a few parts for older L's.
After getting a hard NO from area machine shops I finally found a guy in Portland who would weld up my cracked head. He wanted about $400 to do this so I opted for a new casting instead. It cost me $540 with ship and will be here Friday... 
I got it on eBay from seller RFinc, an ag parts supplier in Illinois.
$519 out the door
https://www.ebay.com/itm/174122904711
The new bare head was $520 out the door.
It came with freeze plugs, stems and seats installed. I will install the old valves and springs and transfer all the studs. Prepping the head and lapping in the valves will take some time but I will start this morning and hope to have the tractor running late this afternoon.
The green paint is about $25 for a single spray can so I am gonna have a quart of oil based paint color matched for about $12, same with the orange.
I gound the valves and was assembling the new head and managed to mangle on of the valve seals. On the back burner until a new set arrives.
What is the correct procedure for installing the valve seals? The ones in the old head were all rubber. New ones have a steel jacket. I pressed them down by hand expecting to feel them snap them into place. They did not and there was about .050 clearance under the bottom edge. I found a deep socket that fit well and tapped...and the rubber lips were torn by the top of the guide.
Do you just stick these on and hope for the best?
Is there supposed to be clearance under them?
MY shop manual doesnt address this
What is the correct procedure for installing the valve seals? The ones in the old head were all rubber. New ones have a steel jacket. I pressed them down by hand expecting to feel them snap them into place. They did not and there was about .050 clearance under the bottom edge. I found a deep socket that fit well and tapped...and the rubber lips were torn by the top of the guide.
Do you just stick these on and hope for the best?
Is there supposed to be clearance under them?
MY shop manual doesnt address this
These sound like those used on early Toyotas I used to work on. The metal “hat” friction-fits against the valve guide and the rubber seal wipes the valve stem as it runs up/dn. Forcing the hat further down damages the seal. (IF... IF... it’s the same type I USED to work on. I have no experience with Kubota seals.)
This sounds the same. I have put these on Toyotas before and there is a noticable "snap" when the pop into place. These Kubota seals did not snap but they seemed solid....wondering if I should glue them down
Or maybe this is a path not to take.
Are the stem holes the same diameter from the original to the replacement head?
Maybe get Kubota seals without the friction hat. Sounds like trouble.
Glue will not hold up with heat. Think maybe take a breath, step back, go back to the Kubota seals which are tried and true.
Are the stem holes the same diameter from the original to the replacement head?
Maybe get Kubota seals without the friction hat. Sounds like trouble.
Glue will not hold up with heat. Think maybe take a breath, step back, go back to the Kubota seals which are tried and true.
I looked at using the stems seal from the old head but they are pretty old.
I have worked with some engines that require the seals to be stuck down with loctite but didnt know if Kubota was one of them
You're right not to.
The rubber seals should go in and stay. Should not need anything to tack them in place.
Light coat of engine oil on valve stems when installing.
Suggest a simple lookup of Kubota part number for original seals and order those.
OK..Let’s think about HOW they work: Oil splashes around inside the valve cover and gets all over the valve stems. The valve going up/dn introduces oil down the inside of the guide and burns up inside the cylinder. When the engine is shut-down... oil slides down the stem and enters the cylinder and creates a lot of smoke on startup. Both are to be avoided.
IF.... IF... the seal is snug against the valve stem.... the entire seal (if not snapped down onto the guide) will reciprocate up/dn along with the valve stem. The “hat” will prevent oil from splashing onto the valve stem and also prevent oil from running down the stem ... thereby preventing oil from getting into the cylinder.
(Even if they are not snapped down or friction-fit onto the guide...as long as the rubber seal is against the stem.)
Do not bastardize the design of the part. IF...IF you have the proper part it should work properly. IMO
IF.... IF... the seal is snug against the valve stem.... the entire seal (if not snapped down onto the guide) will reciprocate up/dn along with the valve stem. The “hat” will prevent oil from splashing onto the valve stem and also prevent oil from running down the stem ... thereby preventing oil from getting into the cylinder.
(Even if they are not snapped down or friction-fit onto the guide...as long as the rubber seal is against the stem.)
Do not bastardize the design of the part. IF...IF you have the proper part it should work properly. IMO