Anything else to do when changing a head gasket?

[Lobanz]

Yes. Valve seals. Excellent.

 

[brain55]

Yes. Valve seals. Excellent.

Valve seals will come with the upper gasket kit. They won't fix worn valve guides though.

Brian

 

[Baby Grand]

[I'm definitely not an experienced mechanic, but I have changed a head gasket before, but that was a LONG time ago. Remind me of any gatchas?]

Does your G5200 have a radiator fan shroud? Mine doesn't, but the Kubota Parts Site shows one (search G5200, click open, go to Cooling System / Radiator and it's part 110, #15852-72330). They are about $55. Wonder if it would fit mine and if it would help.

Also, does yours have an coolant overflow bottle? Mine doesn't, but it has a tube coming out of the neck of the radiator. So I just wedged a aluminum can in the frame and stuck the tube in the can. Don't know if it helps.

Yes, our G5200 has a radiator fan shroud (it was missing when I got the tractor). It collects a lot of mowing debris that would otherwise plug up the radiator.

No, ours does not have a coolant bottle, but it has an overflow tube with a whistle attached to the end. But I don't see any reason that a collection bottle couldn't be installed between the radiator & the whistle ...

 

[buickanddeere]

Don't grind the seats and valves without correcting for sinking the valves . Otherwise compression will be lost.
Odd how nobody mentioned chasing the block threads with a bottoming tap. Champhering the top thread out of the block to ensure their isn't a raised thread holding the head up. No mention of checking across the flat of the head over the thread bosses looking for raised metal around threaded holes. And no mention of using new fasteners. Why trust old stretched head bolts , in particar when there may have been a head gasket leak.

 

[brain55]

Don't grind the seats and valves without correcting for sinking the valves . Otherwise compression will be lost.
Odd how nobody mentioned chasing the block threads with a bottoming tap. Champhering the top thread out of the block to ensure their isn't a raised thread holding the head up. No mention of checking across the flat of the head over the thread bosses looking for raised metal around threaded holes. And no mention of using new fasteners. Why trust old stretched head bolts , in particar when there may have been a head gasket leak.

You're right. I was answering specific to that engine without adding general knowledge in. I do that stuff as second nature, not because it's a Kubota.

Brian

 

[rsallen]

Sinking of the valves!??? WTF is that? This isn't overhead cam engine, and even if it were all the machine shop does is grind off the end of the valve stem to make up the difference for clearance.. Sinking of the valves....never heard of such a thing.
Cleaning the threads on both the bolts and the block are standard operating procedure along with the top of mating surfaces of block and head. Spelled out and written in every instruction I've ever read. No mystery.

Block threads don't deform at the torques heads are typically wound down to without cracking the block. If you want to check the old fashion alloy bolts against each other to check if one or more have started necking out that's fair enough, and if you have the designed stretch head bolts then renew all of them. Otherwise buck, stick with what you know and don't confuse the op.

 

[buickanddeere]

If you are not familiar with lost compression caused by sinking the valves by grinding the valves and seats. You can not claim to be an expert.
So there is something wrong with mentioning the thread chasing and chamfering the top thread? Or just jealous because you never thought of it? Using new fasteners is a given as previously used bolts can not be 100% trusted without using non destructive testing. Which is beyond the abilities of the Kubota owner.

 

[brain55]

Any competent machine is going to address valve and seat height.

Brian

 

[Coyote machine]

Head bolts, new, and torque spec, dry, or lightly oiled?

 

[rswyan]

Sinking of the valves!??? WTF is that? This isn't overhead cam engine, and even if it were all the machine shop does is grind off the end of the valve stem to make up the difference for clearance.. Sinking of the valves....never heard of such a thing.

Yup ... that's exactly what R & R Engine and Machine did when I had them do the cylinder head off my OM647 engine ... and it is overhead cam (dual) ...

BTW ... I reused the head bolts ... they were all well within spec (within the tolerance range for stretching) ... that was about 60K miles ago (at least 1000 hours ago, roughly) ... no problems yet