Question about cylinder head on first gen toolcat with Kubota V2203

[a5t1]

I recently had an issue with my toolcat where it would gurgle after shutting it down. I was loosing a very small amount of coolant over time so I pulled the head and took it to a good engine shop. He checked the head for cracks, cleaned it up and returned it. I replaced all gaskets, put in a new water pump and thermostat as long as I had it apart. When I installed the head, I torqued to the factory manual spec of 66-72, I chose 70. When it fired up, everything seemed fine, no gurgling. After running it , I re-torqued the head bolts, which were a little loose. Again, when it ran I didn't have any issues - coolant was stable and I had heat in the cab. After it got up to temp (thermostat housing showed ~160) I let it heat cycle a few times and shut it down. I noticed that it gurgled. I let it cool and fired it up hours later. I can see the coolant bubbling around in the reservoir and it gurgled again. I'm planning on taking the head off, again. Should I order new head bolts? Any other thoughts?

 

[AdmiralS]

Did you get new head bolts the last time you took it off?

Head bolts are one and done because they stretch. Cannot be used more than once.

 

[a5t1]

I did not. I was told they could be reused. The manual I have states torque to 68.7 to 72.3 ft/lbs. I thought you needed new head bolts if you torque and then turn X degrees. I'll probably order new ones.

 

[laurencen]

the only time I replace head bolts is when the specs have a amount of degrees of rotation after tightening to a initial torque, the extra rotation does stretch the bolts example Subaru motors,

 

[a5t1]

In this case, when the engine gets to operating temp. something isn't holding. Head was checked by a reputable shop. I'm open to other ideas but I think new head gasket, new bolts and see what happens.

 

[denchen]

If you get the head off, clean it, and find a good bit of glass, get it on a flat surface, put some ink on it, gently lay the head on and move it about and you might see if it has any distortion or low spots.

 

[laurencen]

not sure about the Kubota V2203 but last couple we have rebuilt including a Isuzu from Bobcats it may not be the head, with the Isuzu motor the cylinder insert was lower than the block by 0.012 and it caused the same issue when warm, we changed all the cylinder inserts and fixed it up, on the Kubota the space between the cylinder and water jacket was corroded, not much but enough must have been leaking for years

look closely at the top of the cylinder tops, if you have a good steel rule, try to pinch 0.002 feeler gauge between the ruler and cylinder top

 

[a5t1]

not sure about the Kubota V2203 but last couple we have rebuilt including a Isuzu from Bobcats it may not be the head, with the Isuzu motor the cylinder insert was lower than the block by 0.012 and it caused the same issue when warm, we changed all the cylinder inserts and fixed it up, on the Kubota the space between the cylinder and water jacket was corroded, not much but enough must have been leaking for years

look closely at the top of the cylinder tops, if you have a good steel rule, try to pinch 0.002 feeler gauge between the ruler and cylinder top

This is interesting. I ordered new head bolts. When I disassemble it I'll take some pictures and check close.

 

[a5t1]

If you get the head off, clean it, and find a good bit of glass, get it on a flat surface, put some ink on it, gently lay the head on and move it about and you might see if it has any distortion or low spots.

Thanks for the tip, I had a really good shop work the head before install. I'm confident the head is flat.

 

[laurencen]

when you have the head off look real close between the valve seats for a crack, the 843 we rebuilt looked fine but it had a real fine crack between the valve seats

we assembled it two times without success, finally had it magnafluxed and this found the crack, I assumed this was the cause of freezing and no antifreeze, this was a unit that ran good for half hour then blew smoke and bubbles in coolant.