Kubota B7000 Tractor: White Smoke, Pneumothorax Blowing, Z650 Engine Issues & Solutions

Question

Hello, Recently, I have owned the Kubota B7000 tractor. When loaded, it smokes white quite profusely, takes a long time to spin when firing, and has gusts of pneumothorax. Compression 1 cylinder 22 Bar; the second cylinder 25 Bar, while after the oil test 30 and 32 Bar respectively. Also...

eksploatacja · Accepted Answer

These twin-cylinder tractors ignite badly. The first firing requires 15 seconds of glow plug heating.
I have a L 180 with such an engine only reamed to 750ccm. The engine has a pressure similar to yours, also with a smaller one on one cylinder. When heated, the candles fires on a shot. Hot, it fires practically without heating.
White smoke in your case is rather a problem with the injector. Under load it has black smoke. If it smokes white, unburned fuel from one cylinder goes to the exhaust and evaporates there. This may be due to lower compression pressure on one cylinder but it should be on speed and not during operation. Something is wrong. Are you sure it is running on both cylinders? You let go of the tubes on the injectors. They can run on one cylinder. Wono is going to turn, but it does.
I have a service for the B 6000 and L 180 with such engines and boxes, but with a capacity of 550 and 750cc. as if you were interested.
Parts on ebay without a problem., Traktor.com.pl and - www.kubota.pl here I bought heads, valves and rings. Good quality and trouble-free shipping.
I would just wait with this engine demolition in your place.

bearq · Accepted Answer

This tractor should have 30-32 bar compression pressure. 22-25 bar is a padaka.

LENIWIEC_PL · Accepted Answer

Hello. Something this head gasket does not fit very well. Original?

michal_rybka · Accepted Answer

in this picture: you can see elegantly that the cylinder on the left is taking a lot of oil, the cylinder on the right is much better if there are no scratches on the cylinders you can feel under the fingernail, go ahead and put on new rings and put them together. Of course, the planning head, valves to run in and it is good to check the injectors at least, although they will probably need regeneration

bearq · Accepted Answer

Put everything new

bearq · Accepted Answer

If you like to do twice, why not. At this stage, I would dismantle this engine into its first parts, wash everything, seal everything ...

Megawe · Accepted Answer

The problem is to choose the right piston rings for the inserted bushings,

kkknc · Accepted Answer

Your engine is totally worn out. Shaft for measurement. You can see worn cylinder liners with no traces of honing. For this seizure scratches. The pistons have a worn adaptation layer. And no one knows what the clearance is on the shelves and you want to put them back on. You can see elegantly that you lack knowledge about internal combustion engines and their repairs ... And so totally .....

pietervanbaekel · Accepted Answer

Hello, I cleaned up the manual and merged it into a printable file!

Tajfun211 · Answer

I would like to read it, please send it to piotr.zawierucha211(_at_)gmail.com The engine works with two cylinders, but it has blow-throughs, which explains the low pressure, so I will not avoid the renovation, but the question is how big it will be ... Added after 1 [minutes]: This is correct, when I take off the head, I will give a report.

Tajfun211 · Answer

After unscrewing the head, it looks like this, tomorrow I will remove the pistons, today there was no time for more:

Tajfun211 · Answer

There is no scratch under the fingernail, but the inferior sleeve has a small threshold and pitting, so it is rather impossible to sand or replace the sleeve:

The gasket is original, I just put it a little crookedly.

Tajfun211 · Answer

Update after removing the engine, the first ring cracked on both pistons, the rest does not look bad, I wonder if I should replace the rings and shells ...:

Tajfun211 · Answer

The engine will be dismantled and sealed. I am also looking for a grinder to assess what to do with bushings. What else would you advise to check and possibly replace?

bearq · Answer

Replace because how else? The shaft still needs to be removed, check its dimensions, polish the oval if it is within the standard. To check the seat of the bushings, cranks, all wheels in terms of fabrication, not only teeth but also bearings. You really need to check everything that is spinning or moving.

Tajfun211 · Answer

I will do it, it seems that I have also found a grinder who has already made such motors, I will also choose bushings and rings, here is an example of his work: I wonder what could have caused my rings to break ...

bearq · Answer

They often break from overload / temperature.
Such an engine will make you a better bet, but I recommend that you first check the availability of parts for this engine and then return the engine to the factory. If you do not find anything, let me know, I will look for something in my catalogs.
There will be no problem with bushings because their availability is so large that you can easily fit something from another motor and there is no problem with shortening or extending it to a different size.

Regenerating pistons after seizing will not even comment, no self-respecting plant does such a sculpture.

Tajfun211 · Answer

My pistons are not seized, can I use them?

bearq · Answer

You can do anything, but take into account that it will either be okay or not. Since you have already put in so much robots, it is better to add a few pennies and do it as I write the book. Then you will console yourself with this tractor because it will be different. Why is that?

Tajfun211 · Answer

With this random bet, it's not so easy in my neighborhood, as if I was sure that it would be done well, I would return and pay.

Tajfun211 · Answer

I finally found time to dismantle the engine. Do you need to knock out the wedge to remove the shaft because there is a flange that blocks it ?:

bearq · Answer

Rather yes, you have to take everything apart one by one.

Tajfun211 · Answer

Shaft removed, this is how it looks:

Added after 3 [minutes]:

I just don't know what is used where the shaft enters from the clutch side, I thought that the bearing would be there, but after removing the sealant it looks like this:

Added after 39 [minutes]:

bearq · Answer

You can see that the acetabulum is already peeling. Without measurements, nothing can be said about a shaft. In the shaft you have a sliding sleeve instead of a bearing.

Tajfun211 · Answer

The plan is this:
1. The engine block will be put into bushings under the current pistons and new rings will be selected.
2. Shaft to be checked, new main and crank bushings.
3. Head - valve seats / valves for running-in / milling check.
4. All seals and shaft / valve seals new plus this new sleeve bearing.
5. Seat shells and all wheels to be checked.

What else needs to be done / checked?

bearq · Answer

Look for new pistons, you still have to do connecting rods, injectors, pump, check the plane of the block and probably the shaft for grinding. Get the repair manual even from another tractor and although you read it, you will have a picture of more or less what else to pay attention to or check.

Tajfun211 · Answer

So far, I have not found a dedicated manual for the Z650, but I have the Z482, this is the closest engine for which I was able to find documentation.
The manual helped me a lot in understanding the structure, but I can't really be guided by the tolerances and values given there.

In the attachment, the instruction I am writing about.

Tajfun211 · Answer

It is possible that it has overheated, this engine has no water pump or thermostat. The heat exchange takes place passively on the principle of a thermosiphon, while the signaling of high temperature is a whistle mounted on the overflow pipe, but the copy I have does not work ...

Tajfun211 · Answer

Hello, I finally found time to assemble the engine so I would like to share some information about what has been done:
- I found documentation for this model on Japanese servers, which was very useful when assembling: