Bobcat MT52 mini-loader engine question

Auto Doc's said:
Hello CG,

If you or the customer plan on keeping this and getting more use out of it, it will take more than a head gasket. If they just want to "flip it" clean it up and put a head gasket on it, but I advise you to not offer any warranty at all.

If it is a keeper, I recommend you pull the pistons, hone the cylinders and re-ring this engine. It may also be a good time to replace the rod inserts if they are scored up or showing excessive wear.

The black line in the cylinder suggests the upper rings are broken from overuse of starting fluid at some point. The piston skirt does not travel that high up into the cylinder.

The second cylinder with all the fine vertical scuff lines suggests fuel thinned oil and poor oil changes along with the compression rings being weak.

These small diesel engines are more forgiving than their gas engine counterparts
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Well we did have to use starting fluid to get it started and off the trailer. He is looking to keep it and use it. We also found a crack from where the valve seats to the pre-chamber of the head, again on #2, so it's gonna have to be pulled, bored over to get the deep scratches out (machinist said probably 5 thousandths judging by the photos), and rebuilt. This will be my first time rebuilding a 3 cylinder Kubota and any Diesel engine really.
 
Auto Doc's said:
It is difficult to tell that this engine has liners. I'm used to larger tractor engines where they are more pronounced.

Sounds labor intensive just trying to get it all removed and torn down, but these machines are not cheap to replace either.
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Yeah, it will be compared to the typical riding mowers that I usually repair, but it will be worth the experience if nothing else and he has been waiting for another shop to even touch the loader since September with no work done on it since. I don't think it has liners from the factory but I really haven't inspected it that closely yet either. Either way it will be the machine shop's problem 😂.
 
I will about guarantee that 5 thousands won't even take the surface scratches out. I would guess the out of round and taper is more than 5 thousands.
 
Craftsman Garage said:
Well we did have to use starting fluid to get it started and off the trailer. He is looking to keep it and use it. We also found a crack from where the valve seats to the pre-chamber of the head, again on #2, so it's gonna have to be pulled, bored over to get the deep scratches out (machinist said probably 5 thousandths judging by the photos), and rebuilt. This will be my first time rebuilding a 3 cylinder Kubota and any Diesel engine really.
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Hello CG,

Read up on head gasket thickness and crush heights when torqued. This is critical because diesel engine rely on the high compression pressures to fire the fuel. If the machine shop is rebuilding the engine as a long block, it pays to mention it to them. I do not suggest trying to save money by doing your own assembly of the long block.

These are much more critical about head clearances than typical gas engines.
 
Auto Doc's said:
Hello CG,

Read up on head gasket thickness and crush heights when torqued. This is critical because diesel engine rely on the high compression pressures to fire the fuel. If the machine shop is rebuilding the engine as a long block, it pays to mention it to them. I do not suggest trying to save money by doing your own assembly of the long block.

These are much more critical about head clearances than typical gas engines.
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I was planning on just sending the block into them for honing and that was it. I was going to be the one doing the rebuild once I got the block back. I'm interested, what are you on about though?
 
ILENGINE said:
I will about guarantee that 5 thousands won't even take the surface scratches out. I would guess the out of round and taper is more than 5 thousands.
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It may have been 5 thousandths or 50 thousandths, I can't remember. None of this is final and will ultimately be determined by the machine shop and how much it takes to get the scratches out, even if that means putting liners in to get back to a standard size.
 
Craftsman Garage said:
I was planning on just sending the block into them for honing and that was it. I was going to be the one doing the rebuild once I got the block back. I'm interested, what are you on about though?
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Hi CG,

Okay, so you are just going with a basic "refresh" and not having the block machined and sleeves installed.

Like I mentioned earlier though, make sure to study the service information in case there is any mention of various thickness head gaskets. Some diesel engines were more critical than others.

I've rebuilt a number of Yanmar engines but am not that familiar with the smaller Kubota 3-cylinder diesels.
 
Auto Doc's said:
Hi CG,

Okay, so you are just going with a basic "refresh" and not having the block machined and sleeves installed.

Like I mentioned earlier though, make sure to study the service information in case there is any mention of various thickness head gaskets. Some diesel engines were more critical than others.

I've rebuilt a number of Yanmar engines but am not that familiar with the smaller Kubota 3-cylinder diesels.
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From what I've seen, the Yanmar and Kubota 3 cyl diesels are very similar. I've got a yanmar 3 cylinder diesel in a 6x4 gator here in the shop (not my project though) and they are built with what looks to be very few differences. Thanks Auto Doc's, I'll take all the knowledge I can get :D.
 
Auto Doc's said:
Hi CG,

Okay, so you are just going with a basic "refresh" and not having the block machined and sleeves installed.

Like I mentioned earlier though, make sure to study the service information in case there is any mention of various thickness head gaskets. Some diesel engines were more critical than others.

I've rebuilt a number of Yanmar engines but am not that familiar with the smaller Kubota 3-cylinder diesels.
Click to expand...
You're saying here if I do the rebuild and use a composite or head gasket other than an MLS like what was in here originally?
 
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