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

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 suspicion is the rings and / or pistons and / or sleeves
I also checked the valve clearance, it was 0.15-0.25; I adjusted it to 0.2 all.
I also did a filter-oil-strip service with engine rinsing (I have the impression that the belt is as old as the tractor, i.e.> 40)
I'm waiting for the engine to start, so I'm looking for a service for the Z650 engine with a capacity of 653cc and a source to buy / add rings and gaskets - a warm request for help in this regard.

There is a lot in the network for newer engines, but there is nothing specific about it.

Below are some photos and a link to the movie.

https://youtu.be/LvCyCOUdRxY

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.

eksploatacja wrote:

Your white smoke is rather a problem with the injector.

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

eksploatacja wrote:

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 ..

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]:

bearq wrote:

eksploatacja wrote:

Your white smoke is rather a problem with the injector.

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

This is correct, when I take off the head, I will give a report.

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

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

in this picture:
https://obrazki.elektroda.pl/6134927600_1598131246.jpg
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

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.

Put everything new

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 wrote:

I am wondering whether or not to replace the rings and bushings themselves.

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

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?

Tajfun211 wrote:

I am also looking for a grinder to assess what to do with bushings.

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.

bearq wrote:

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.

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:
https://www.malytraktor.pl/forum/viewtopic.php?f=35&t=1223&start=20#p12479

I wonder what could have caused my rings to break ...

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.

My pistons are not seized, can I use them?

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

Tajfun211 wrote:

My pistons are not seized, can I use them?

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.

Megawe wrote:

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

Why is that?

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.

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 ?:

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

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]:

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.

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.

michal_rybka wrote:

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

You can see elegantly that you lack knowledge about internal combustion engines and their repairs ...
And so totally .....

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?

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.

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.

bearq wrote:

They often break from overload / temperature.

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 ...

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:

PL_B700...pdf (2.99 MB)You must be logged in to download this attachment.
PL_B700...pdf (2.43 MB)You must be logged in to download this attachment.
PL_B700...pdf (2.2 MB)You must be logged in to download this attachment.
PL_B700...pdf (2.47 MB)You must be logged in to download this attachment.
PL_B700...pdf (1.77 MB)You must be logged in to download this attachment.
B5000-700..3).pdf (21.82 MB)You must be logged in to download this attachment.
- sleeve replacement and block planning:

- replacement of brokers (two of them were rotten and clogged with some kind of putty):

- replacement of the bushings, shaft checked, everything OK:

- making gaskets, replacing seals:




- replacement of rings


- replacement of guides and valve seals, milled seats and lapped, planned head and of course a new gasket:

- painting and assembly:


- starting the engine and first measurements:

https://youtu.be/zcr5NfJ-Y_k


https://youtu.be/nDrM_w1pgSs

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