How to Remove Giant Crankshaft Nut from L3710?

[Mr Haney]

I have to replace the front cover on my Kubota myself because the guy who said he would do it has disappeared. I got the radiator and other obstacles off. Now I have to remove the nut on the front end of the crank.

This appears to be a 45mm nut. My biggest impact socket is 23. My biggest crescent wrench is about 44.

How do I get this off? Are they insanely overtorqued like just about every other fastener on the Kubota?

I don't even know if I can immobilize the crank. This tractor has HST. Also, I'm not sure whether I could get the impact wrench in there if I managed to find a deep socket.

 

[Mr Haney]

It looks like the nut is really 46mm or 1-13/16". The manual puts the torque at 101-116 ft.lbs., and it says too much torque ruins the oil slinger, so I suppose Kubota must have taken the spec seriously.

 

[Vigo]

Well a sufficiently big deep socket would probably work as long as the wall thickness didn't interfere with the crank pulley. There may be a special tool for it, something like this tool which is for holding old Honda engine crank pulleys (though this is to hold the pulley, not the nut, but the shape gets you the idea).

An old trick for breaking loose crank bolts on cars (for doing timing belts/chains etc) is to just put a socket and breaker bar on the bolt/nut, let the breaker bar rest against the frame or ground on the side the engine spins toward (engines usually spin clockwise when viewed from the 'front'), and then use the starter to bang the breaker bar into the frame/ground and break the nut loose. It's crude but it does usually work. You still need a tool that fits that size nut.

As far as locking the engine up, diesels are a bit harder because pulling injectors and glow plugs is harder than spark plugs and the holes might be smaller, but you can actually put a piston near TDC and feed a rope down into a cylinder such that it wont be able to push upward, sort of locking up the engine. On a tractor if you have 'live pto' and depending on whether there is an internal electric pto clutch or overrunning clutch which would defeat this, just putting the pto in gear and then holding the pto shaft might 'lock' the engine even though it's HST trans.

Just some ideas from a car mechanic who's newer to tractors.

 

[Mr Haney]

Thanks for the help. I don't think I want to pull the head off the engine. I'm in pretty deep already. Maybe there is a way to rig up a strap wrench, or I guess I could put a Vise Grip on the shaft.

I found a 3/4"-drive impact socket which can be here in a couple of days for $60. Cheaper than the dealer's labor.

 

[PoTreeBoy]

Thanks for the help. I don't think I want to pull the head off the engine. I'm in pretty deep already. Maybe there is a way to rig up a strap wrench, or I guess I could put a Vise Grip on the shaft.

I found a 3/4"-drive impact socket which can be here in a couple of days for $60. Cheaper than the dealer's labor.

If you can get the socket and breaker bar in the right position, you might be able to loosen it with a sharp hammer blow and let the mass and friction of the engine hold it. If not, try rigging an old v-belt as a strap wrench on the crank pulley.

 

[JimmyJazz]

Applying heat is often used in these situations. Youtube may help. Good luck.

 

[Vigo]

you might be able to loosen it with a sharp hammer blow and let the mass and friction of the engine hold it.

Brings to mind another idea.. you MIGHT be able to get away with renting a fan clutch tool set and using it on the nut at an angle. Or if not, you might be able to rig a way to accomplish the same thing as a fan clutch tool designed to be used with an air hammer, if you have one.

 

[Mr Haney]

Thanks for all the assistance.

I found two Youtubes of different guys removing the same nut on different Kubotas. One guy was in a place like India or Pakistan, and he used a chisel and hammer to knock the nut loose. The other guy is in New Hampshire. He hit one side of the nut with an air chisel. He confirmed it's 46mm.

He said he had to split his tractor to get clearance to get his front cover off, but mine looks like it will not have that problem.

I have a big socket on order from Grainger.

The thing I really dread is cleaning the old gaskets off the block. I hope it's not too stubborn.

 

[ve9aa]

I did this on a Subaru (but I am farrrr from a mechanic). I held the crank pulley with a vicegrip type of chain-wrench . I took an old leather belt (the type you wear() and put it around the pulley so it wouldn't get damaged then wedged the end of the vicegrip in somewhere where it couldn't turn.

Then I had a breaker bar with a big socket with a 4' pipe I "reefed on".

Came loose first try.

 

[lugbolt]

I use a 46mm axle nut tool made for certain ATV's. It works awesome. Better than the Kubota tool ever did. This one I have is a Kent-Moore tool I think for the Yamaha Raptor 660 (could be wrong about the application), made to remove the nuts that hold the sprocket onto the axle. 1/2" drive. I want to say it was about $90 when I bought it in I think 2001.

 

[Motion]

An impact wrench will pop it loose, clean the threads and apply penatrant first. The problem will be properly touquing the nut on reassembly. Another thought would be once you have the correct size socket cut it long enough to cover the nut then take a piiece of 3/8x2" flat bar drill a hole and weld it to the socket, then get a yoke of the correct diameter and number of splines and put a piece of pipe through the "U" joint holes.

 

[Mr Haney]

Yesterday, I placed an order with Grainger, and today I received an impact socket. It's a Proto 46mm deep socket, model J07529L. It fits the nut perfectly. It's labeled 1-13/16", which is within 0.04mm of the Japanese size. This may help other people, because that nut is used on other Kubota motors.

I paid over $60 because I wanted something that would arrive fast, but there are other ones out there for less.

It's a 3/4"-drive socket. I didn't have any adaptors to make my 1/2" impact wrench work with it, or at least I don't think I did, so I hit Harbor Freight and grabbed a set of adaptors and some universals. I already had a 1/2"-3/4" adaptor for a socket wrench, but I figured I might as well get impact-rated stuff, since I may need it for other things. And because I like buying tools.

I also picked up an Icon 24" 1/2"-drive breaker bar and a Bremen chain clamp

I believe I can get the socket and a universal on the nut, so the impact wrench should knock it right off. Failing that, the breaker bar should make short work of it, given the modest torque figure. I should be able to put the chain clamp on the pulley to lock it up well enough to get 101 ft.lbs.

 

[ve9aa]

Great job Mr. Haney !

 

[Mr Haney]

Great job Mr. Haney !

Thanks. Unfortunately, it appears I can't get at the lower two screws on the front cover because the front axle is in the way. I am afraid the engine has to come out. That's too deep for me.

 

[Mr Haney]

Is there any possibility I could plug this hole with epoxy so I could run the tractor long enough to get the loader off? I don't know a whole lot about engines. When I discovered the hole, the engine was idling, and a little oil was squirting out, but it didn't appear to be under pressure.

There is a tiny chance I can repair this thing with the loader off, but with it on, there is no hope. Removing the loader without hydraulics is not possible with this model, and anyway, I would have to back the tractor away from the loader.

I've seen people talking about grinding engine block holes and then applying some type of epoxy, but that would shoot bits of aluminum into the oil pan. I would only be able to clean it with solvents and jam something in there.

 

[PoTreeBoy]

Is there any possibility I could plug this hole with epoxy so I could run the tractor long enough to get the loader off? I don't know a whole lot about engines. When I discovered the hole, the engine was idling, and a little oil was squirting out, but it didn't appear to be under pressure.

There is a tiny chance I can repair this thing with the loader off, but with it on, there is no hope. Removing the loader without hydraulics is not possible with this model, and anyway, I would have to back the tractor away from the loader.

I've seen people talking about grinding engine block holes and then applying some type of epoxy, but that would shoot bits of aluminum into the oil pan. I would only be able to clean it with solvents and jam something in there.

JB Weld Steel Stik is an epoxy paste. You knead it in for hand to mix it then stick it in the hole. You can get it at auto parts or big box stores. That should slow it down enough to get your loader off.

 

[Russell King]

Just check the oil level run it for a few minutes and see how much is spitting out the hole and determine if you need to do anything for the hole (while removing the loader). Then check the oil level again. The oil is probably not being pumped out under pressure where the hole in the cover is at so it will just be splash and spray leaking when running.

You can probably just shove some plumbers putty in the hole and it will stay long enough to get the loader off.

The epoxy mentioned above would be “better “ but more permanent if it gets on the wrong thing.

 

[lugbolt]

if the axle is in the way, you can loosen all of the front frame bolts while supporting the ENGINE (or transmission near the clutch housing), and let the front frame just pivot downward a little. That way you won't have to totally remove it. They're not too hard to get off really (the whole front frame).

 

[Mr Haney]

The oil pan is under the engine. Is it safe to put a jack on the pan, or will it crush it?

 

[Mr Haney]

I just took a look at it.

I can't access the screws by removing the front axle, because the frame itself obstructs the screw heads above the axle. It looks like the only answer is to remove all the fasteners attaching the engine to the front frame, which go all the way back to the rear of the loader, and move the front frame forward.

To do this, I have to have the loader off. To get the loader off, I have to have hydraulics. To get hydraulics, I need to seal the hole in the cover.

I don't know what would happen if the engine were detached from the front frame, held in place by whatever fasteners are at the rear, and then jacked up. I assume it must be possible to jack up the oil pan and engine without breaking the engine loose from the transmission.