Kubta b7100 engine removal

[KubotaVT]

I'm looking for some experienced b7100 owners here to perhaps give me a little advice.

This winter I'm doing a rebuild of my b7100's engine (blowing lots of oil at idle and lots of blowby at any time when running)...and I'm wondering how to get the engine out. I've heard it's neccessary to split the tractor, but for obvious reasons I'd like to avoid that unless I have to do it. So..the questions:

-Is there a way to get the engine out without splitting the tractor? Maybe removing the front driveshaft to access the oil pan?

-If not, how would I go about splitting the tractor? I haven't done this before, so help on the process would be appreciated.

-Also, on a side note, how do I do a compression check?

Thanks!!

 

[dex3361]

Depending on the condition of the engine you could do some work without removing the engine. If you are going to do any crank work it has to come out. You can: replace the main bearings, remove the pistons. replace the piston rings, replace the crank bearings, remove the head and perform any head work that needs to be done. The problem is that you really don't know what has to be done until you tear it down. Then the condition of the components should determine what to rebuild/replace or how much farther to go. What series engine is it? I think that is a D905 3 cylinder if my info is correct. If you go to tear it down let me know I may have some reference material for that engine.

 

[Gator6x4]

If you do decide to try to rebuild without spliting, be very - very careful with the crankshaft. Protect as well as you can from grit and grime falling down on it, especially when deglazing the cylinder walls. I would also recommend washing everything two our three times with dishwashing detergent added to the wash water. Then using low pressure air. High pressure air will force small grit particles into some very small and later damaging places.

 

[dex3361]

If you do decide to try to rebuild without spliting, be very - very careful with the crankshaft. Protect as well as you can from grit and grime falling down on it, especially when deglazing the cylinder walls. I would also recommend washing everything two our three times with dishwashing detergent added to the wash water. Then using low pressure air. High pressure air will force small grit particles into some very small and later damaging places.

Great points.:thumbsup:

 

[Thomas]

Darn good advice has been given!
Take notes/photos also you may consider service manual,yes manual pricey but well worth the cost.

 

[brain55]

If you have the ability to pull the head and remove the rods and pistons you have the ability to remove the engine.

The way I would go about doing it is to remove the front axle frame assy. leaving the radiator attached. If it has a loader, I would raise it all of the way up, block it up with some angle iron cut to the proper length to hold it at the full height, remove the hood and side panels, which also means removing the muffler and air cleaner. Drain the coolant and remove the radiator hoses, put a jack under the loader frame or brake/clutch pedal shaft lifting it up just enough to take the weight off of the front end, loosen the clamp on the driveshaft cover and slide it up, then remove the 8 bolts on each side that hold the axle frame to the engine. After that you can just pull the whole front end assy. away from the machine. Now there is room to remove the oil pan.

Now if you find that you do need to remove the engine it is right there out in the open. All you would have to do is remove the hydraulic lines to the pump, the fuel line from the tank, and the bolts holding to engine to the clutch housing.

Odds are it will need to be rebored. I have just reringed them, but the proper repair would have been to bore the cylinders and replace the pistons and rings. On this size Kubota engine you can replace the rod bearings, but to replace the main bearings the engine has to be removed. The crank and main bearing assemblies slide into the block from the rear of the engine.

Let me know if you have anymore questions.

Brian

In order to do a compression test you will need the proper adapter to either screw into the injector holes or the glow plug holes and a compression gauge that reads at least 500 psi, intended for diesel engines.

 

[KubotaVT]

Thanks for all the great info everyone. This will be EXTREMELY valuable as I go further in the project, possibly next weekend. I'm doing it with a friend and we just want to be sure about what we are doing. One more question...is the Kubota b7100 engine a sleeved engine? You guys mention honing, but I was under the impression that it was sleeved and I could replace those...I guess not. I have the capability to hone with a drill attachment my friend owns. Unfortunately I'm not made of money, and therefore a honing, a ring replacement, a head gasket replacement, and possibly one new cylinder (if I find it's burnt one) is about as far as I can go at this point. Thanks again!

 

[brain55]

Yes, it does have liners, but they are dry liners and they aren't like wet liners where you can just drive out the old ones and slide in a new liner and piston assy. You can typically get at least one oversize bore out of the liner before it needs to be replaced. All of the liners I have had done, needed the liner machined out, the new one installed, and then it needed to be honed to size by the machine shop.

Brian

 

[KubotaVT]

All right, sounds good, at least they'll hold up to one light honing. Thanks again for all your help, it's great to hear from a bunch of people more experienced than myself. I'll be coming back once I get further in the project.

 

[charlz]

In the WSM manual they show the front wheel assembly comes off and then the motor. I think by removing the front wheel assembly you would have all the access you need to the motor without disconnecting it from the transmission. would have to figure out how to support it really well though.

 

[KubotaVT]

Thanks for all your help Brian, just one more question. Can I hone the cylinders without removing the engine? I haven't done this before, and my instinct would say all the crap I knock off the cylinder walls would fall deeper into the engine. How would I go about preventing this...if it's even possible. Maybe I'm just being stupid because I haven't done this yet and am forgetting something. Thanks again!

 

[brain55]

Thanks for all your help Brian, just one more question. Can I hone the cylinders without removing the engine? I haven't done this before, and my instinct would say all the crap I knock off the cylinder walls would fall deeper into the engine. How would I go about preventing this...if it's even possible. Maybe I'm just being stupid because I haven't done this yet and am forgetting something. Thanks again!

If by honing, you mean clean-up the cylinder walls and deglaze them. Then, yes you can. If by honing you mean correcting out-of-round, or taper, or open them up for oversize pistons. Then, no you can't.

There is not that much "crap" to worry about. You have the pan off anyway. I go through several cans of Brakleen getting all of the residue from honing off of the cylinder walls, crankshaft, and crankcase. I know some will say that the honing grit will get down into the main bearings. I haven't seen this happen or if it did it never was enough to significantly reduce the life of the crank or bearings. By doing an "in frame" rebuild like this, you are cutting corners anyway. Will you get several more years of operation out of the machine? More than likely, but there is no guarantee. If you are looking for 6000 hours or more of operation, the correct way would be to completely disassemble the engine and have a machine shop bore it.

Brian

By the way, if I was doing this I would take the head apart and inspect the valves. Many times you can get away with just lapping the valves. But if you don't check the head out, and just put it back on, then you might have just wasted your time doing a ring job.

 

[KubotaVT]

Alright, I'll make sure to check the head out too, valves and all. And yes, I was only planning to do a quick deglazing, basically a polish. I know it won't be perfect by the time it's done, but hey, it's blowing a ton of oil now, so a few little things might go a loongg way. I just want to stop that dreaded blue smoke at idle and under load. I don't have time or money to do a crazy ground up rebuild at this time, and this is basically an educational project to get a good working tractor that'll last me a while. Basically a simple restoration. Thanks again for all your help.

 

[czechsonofagun]

Don't you think that engine swap would be cheaper and better solution in a long term? It would save you work, time and profesionally remanufactured engine should last several thousand hours.

 

[Argosy]

Another vote for a swap, even a high hour in fair condition. If the cylinders are out of round and tapered deglazing is a waste of parts. Same for the valve guides and stems, that could be the source of the oil leak. Changing rod bearings but not cam and mains without knowing clearance could leave the rods oil starved.

You could put a few hundred dollars into this and end up with more problems than you started with.

 

[brain55]

Don't you think that engine swap would be cheaper and better solution in a long term? It would save you work, time and profesionally remanufactured engine should last several thousand hours.

Do you have a source for a remanufactured engine for this machine with pricing? If you do, I would love to have it for future reference.

Another vote for a swap, even a high hour in fair condition. If the cylinders are out of round and tapered deglazing is a waste of parts. Same for the valve guides and stems, that could be the source of the oil leak. Changing rod bearings but not cam and mains without knowing clearance could leave the rods oil starved.

You could put a few hundred dollars into this and end up with more problems than you started with.

Having done this several times for people that could not justify the cost of a full rebuild, it works out fine. Yes there is a line where it shouldn't be done. If the engine was severely dusted or has many hours on it then yes it could be a waste of parts. But with a slight taper or out of round he will get many more hours of operation out of it before it has to be done properly. I think for a guy doing the work himself it is worth the $500 risk. I agree that the head needs to be looked at and repaired as needed. As far as cam and main bearings, first of all this engine doesn't have cam bearings, secondly Kubota's nearly never have bearing issues at all. In 23 years of working on primarily Kubota equipment or equipment with Kubota engines, I have seen one bearing failure.

Brian

 

[petes]

I agree with Brain55. Although I opted for a swap (marine generator D950 into my B7100) because my $500 tractor came with a cracked head and I lost patience trying to find a head for what I though to be a reasonable cost), I first started checking out the guts of my D750 in prep for a rebuild. ~1750hrs, air and fuel filters looked like they'd maybe never been changed. Cylinders liners were worn and stepped, the middle liner pitted and piston damaged from a cracked/leaking head. Despite the abuse when I tore into the bottom end found the bearings and journals in perfect condition. Plastigauge'd right in spec, no scoring or wear. Buttoned it back up fully intending to put in liners, pistons, rings and a valve-jobbed head if I could find it.

Oh, and to the original question... just split the tractor and get the engine on a stand. You can't "get the engine out" without splitting since the engine block is what holds the front and rear of the tractor together. Although it sounds daunting, it's not hard at all and does not require any special skills or tools. The 2-4 or so extra hours to clean, remove the loader and subframe, split the tractor and put it all back will be well worth the improved access and ability to really check things out and work clean, plus you'll be able to get a look at the clutch while it's split. If just pulling the head to do valves of a gasket, I'd definitely do it in frame, but if you want to pull the pan and have a look at anything, especially removing pistons/honing looking at bearings, etc. you'd be cursing the limited access and dirt. You'll be glad to have the engine by itself on a stand or bench.