Kubota MX4800 lost all coolant

[big bubba]

if you drop pan, you can also check rod/main clearances w/plasti guage while you're at it. plus cond of crank journals
best regards

 

[5030]

Can you drop the oil pan and see if the rod is loose if you don't have
a warranty? Maybe you just need to tighten the rod bolts or replace
the rod bearings? Just a thought


willy

I don't think so. Kubota uses insert mains and you don't 'tighten them up' to restore operating clearance. Besides, hammering like it it is, it's hammering the crank throws as well. Why it's imperative to get it apart NOW. A set of mains is a lot cheaper than a crank.... and, once the rod bolts are torqued, they cannot be reused because they stretch and have to be replaced with new ones. Just like an automobile engine.

That ain't piston slap, that is rod knock.

 

[dodge man]

Unfortunately I think 5030 has the problem pegged.

 

[5030]

Unfortunately I think 5030 has the problem pegged.

Hate to be the bearer of bad tidings but the more times you run it, the worse the damage becomes. I guess if you have Kubota Insurance or a warranty on it, don't matter because at some point it will get terminal. Terminal is usually a locked up motor or a hole in the block. Then it's reman time.

 

[gbward3]

I dropped the pan yesterday and the piston rod bearings looked factory new. When I checked the valve clearance to the rocker arm they were all within spec.
If the noise is a tappet, connecting rod, or valve would the gap still be within spec?

I called the Kubota dealer and they said they don't rebuild engines they only replace them. Cost $15k. The tractor was $22k new with $5k loader which means the tractor new was worth $17k new.

I have rebuilt tractor engines before but can't find anything that is damaged.

 

[ruffdog]

Hmm, where did the coolant go? Did it over heat and boil over? Did it leak internally and burn it (out the exhaust)? Is it in the oil pan? Many times a rod issue gets real loud when you throttle it and the rpms are climbing (under load). Is it still losing coolant? Did it suck debris into the cylinder and the head/piston got pounded? If so, a piston can expand and crack the cylinder or the head can crack. There are lots of things to check before you tear it apart.

 

[gbward3]

Hmm, where did the coolant go? Did it over heat and boil over? Did it leak internally and burn it (out the exhaust)? Is it in the oil pan? Many times a rod issue gets real loud when you throttle it and the rpms are climbing (under load). Is it still losing coolant? Did it suck debris into the cylinder and the head/piston got pounded? If so, a piston can expand and crack the cylinder or the head can crack. There are lots of things to check before you tear it apart.

The coolant leaked out of a hole in one of the coolant lines which has been replaced.

 

[5030]

Do whatever you want to, it's your dime. I told you what to do, whether you heed that or not, I really don't care. I just know what the end game is. Late model Kubota engines are parent bore thin walled castings so collateral damage happens quickly and it's usually terminal. Not tappets not valves, not anything but rod knock. You ran it dry (of coolant) and now you get the end result. Your video proclaims that quite nicely.

Like they say, poop happens. in this case, it happened to you. You cannot ascertain insert damage without removing the rod cap, unless it's so bad you can wiggle the big end around on the journal. Not that bad yet, but it will be. Once you cut through the Babbitt, it's all downhill from there. Impossible to maintain a boundary layer of oil on an insert with compromised bearing surface.

Did you physically grab the big end and try to wiggle it? bet not.

 

[gbward3]

Do whatever you want to, it's your dime. I told you what to do, whether you heed that or not, I really don't care. I just know what the end game is. Late model Kubota engines are parent bore thin walled castings so collateral damage happens quickly and it's usually terminal. Not tappets not valves, not anything but rod knock. You ran it dry (of coolant) and now you get the end result. Your video proclaims that quite nicely.

Like they say, poop happens. in this case, it happened to you. You cannot ascertain insert damage without removing the rod cap, unless it's so bad you can wiggle the big end around on the journal. Not that bad yet, but it will be. Once you cut through the Babbitt, it's all downhill from there. Impossible to maintain a boundary layer of oil on an insert with compromised bearing surface.

Did you physically grab the big end and try to wiggle it? bet not.

I removed the rod caps and all the babbit looked like new. If the babbit looks good do you think it's the main crank bearings?

 

[ruffdog]

Over heating like that....I'm wondering if a cylinder liner is loose???????

With the pan off, can you reach up in there and move the liner at all? A loose liner will eventually break the flange at the top, will slide down to the crank, and will take the rod and block with it.