Head Gasket Replacement on my Kubota

[RobJ]

Rob, did you disassemble your engine without draining the antifreeze?
I did that as a kid and it cost me a totally rebuilt engine?
Jim

Yep, you can see the gray bucket in one of the pics (actually the picture was taken while it was draining) I either didn't notice a block drain or it doesn't have one. Pulling the bottom hose would not have helped because I drained the radaitor using the drain plug.

The oil will be changed before start up so I'm not worried about a little that got down there. No damage to the cylinder because those were dried with compressed air and towels and wd40.

What was the reason you had to get a complete rebuild? I can't see the need for a rebuild just because a little water got down there unless it wasn't cleaned out or the oil changed? As long as you clean it up...no problems.

 

[MrJimi]

Way back in the early 60"s, the mechanic told me that the antifreeze would soften all the bearings and it would start to knock real soon. I dont think this was a sales pitch to rebuild an engine.
I dont think water would hurt much but I'm sure the antifreeze is not a good thing
Looks like your doing a nice job.
Jim

 

[wushaw]

RobJ, I don't see reason there to cause a overheating issue.
That head doesn't look bad at all. I wouldn't shave much if any at all, straight edge it, grind valves, check guides...etc and put her back together. I would remove the radiator while you have it torn down and get it rotted & repaired.

 

[RobJ]

RobJ, I don't see reason there to cause a overheating issue.
That head doesn't look bad at all. I wouldn't shave much if any at all, straight edge it, grind valves, check guides...etc and put her back together. I would remove the radiator while you have it torn down and get it rotted & repaired.

I don't really either. The valve concerns me, any high pressure leak will cause the temps to rise. I never boiled over or had the whistle blow, just ran hot. But the engine did sound ok...or I should say it hasn't changed since I had it. I just became aware of the heating problem when I added a temp gauge.

Thanks for looking,
Rob

 

[Bob_Young]

Thanks for the great slideshow, Rob. Much appreciated. Hope it goes back together without a hitch and solves your temp. problem.
Bob

 

[638]

Rob, I don't believe that you will have a clearance problem by resurfaceing the head. Piston to head clearance will only change if you resurface the block. Just make sure that the valves don't stand proud of the resurfaced head. If I were doing the work I would grind valves & seats first, reinstall the valves and then resurface the head. That way, you are sure that the clearance will not have changed.

ron

 

[johnk]

Very nice job on the pics. How many hrs do you have in the disassembly roughly? Cleanliness is a good thing when doing this...I used to use brake clean to wash all the stuff.... Keep us posted..

 

[RobJ]

Rob, I don't believe that you will have a clearance problem by resurfaceing the head. Piston to head clearance will only change if you resurface the block. Just make sure that the valves don't stand proud of the resurfaced head. If I were doing the work I would grind valves & seats first, reinstall the valves and then resurface the head. That way, you are sure that the clearance will not have changed.

ron

It has been a while since I did this professionally and the guy at the machine shop quoted your exact words. But I reminded him as you hit on that the valves protroud(sp?) below the face of the head. So it would lower the valves a bit. The pistons have recesses in the dome for the valves. I just really don't want to get in that mess of head clearance. My Kubota manual says if clearances are out of spec to check the rod bushing and bearings...huh?? And there is only 1 head gasket listed, no thick ones. After the guy looked at it he recommeded not to surface the head. That should save me some money. I should be able to get it today. I forgot to grab the camera so I don't have a picture of the poorly seating valve.

He is going to bead blast everything which is cool. I also made copies of the manual on the valves just in case. He was impressed with the 60 degree/ and 30 degree cuts in the seats the manual recommended. This is a proceedure done on car engines to aid in performance (I used to do this on my and friends heads I worked on). He said they are getting all the power possible out of this little engine. Works for me!!

 

[RobJ]

Very nice job on the pics. How many hrs do you have in the disassembly roughly? Cleanliness is a good thing when doing this...I used to use brake clean to wash all the stuff.... Keep us posted..

Right now I probably have about 2.5. About an hour in removing the head. Then the other 90 minutes is clean up, inspection, removing the valves, etc. Working on a tractor that's waste high is much easier than a truck or bigger machine where you have to climb up on everything.

I hope to pick up the story after Christmas when I put it all back together!!

 

[BTDT]

A few last general shots. Injectors, glow plugs, etc. The whole process to remove the head took about 45 minutes, no air tools on this one. Then about another 45-60 minutes to clean up and inspect. Again a little worse than I thought since the engine only has about 1300 hours on it.

It's off to the machine shop this afternoon to see what the damage will be. I'll probably get the "well you need new valves, guilds, blah blah. Wonder if I can rent the valve machine for 30 minutes. But he'll have to surface the head for me, my ROS sander is only good for clean up.

I'll update soon I hope...

Rob

BTW, has anyone else done this. With surfacing of the head, I'm concerned about clearances. The manual says .0217-.0276. Pretty tight and they want you to check with some plastagauge. .002-.003 should clear up what I need. I just don't want to push it or do it if Kubota says not to.

Thanks...

Soooo, does your wife know your using her blanket/bed spread to lay your parts on