B7000 Z650 engine

[finchrat]

Hi All,

I need to replace the engine in my B7000 kubota.. Cracked block etc..this one is hopeless..It uses the z650 but I cant find that engine anywhere. Does anyone know if another 2 cyl engine will fit in this tractor?


Thanks,

Damon

[Service Dept Vic]

Damon, Are you kiddin me! You've been up and down the block with that Kubota!

The problem with a replacment engine is dimensions and transmission integration, the B6000 eng may work, let me investigate a little more but that would be my first guess.

[finchrat]

Vic,

My neighbor had the kabota field tech over to fix his tractor so I had him look at mine. He knew a few things I didnt. He said there is some water in the engine oil..not just water in the radiator like I had thought. He says most likely its a cracked block and I might as well look for another engine. I wish it was just a freeze plug but he didnt think so. I may still check that but its not looking good. Im lost without my kubota!


Damon

[Service Dept Vic]

Ya, I'm not sold on that guys 15' casual observation/evaluation that it's a "cracked" block.

Water gets in oil of your Kubota from normal condensation, that's why there is a breather tube on the engine. As the oil heats up, it burns off that condensate.

Are we talking about a "massive" amount of water in the oil, or cloudy/milky looking oil?

Is the radiator full of oil as well? Have you done a static pressure test on the cooling system. Have you pressured up the system, started up the tractor to see if the pressure rises on the test guage? These are critical tests to evaluate the problem.

Read our article on "Water in the Cooling System, watch our video on this exact situation.

Here's the good news: I doubt the block is cracked.

If a frost plug popped it won't be one you can "see".

You've got some homework to do. Report back and let me know what you find!

[Mr. K]

Agreed. There are frost plugs all over your engine block - some in really hard to get at places (ask me how I know!). There is one in the cylinder head, one behind the gear case cover a few on the sides of the block, etc.

[finchrat]

Guys,

The oil color is cloudy and its about 1/4" above the full level of the dipstick. The radiator has alot of oil in it but I know it floats on water so dont know just how much but if you stick you finger in the fluid it comes out pure oil. The tractor doesnt have more than 10 minutes running since I rebuilt the head and changed the oil as well. Running the tractor does not increase pressure at the radiator opening. I was able to pump it up till I could pump no more..the gauge isnt working on my old stant radiator tester but it held the pressure. There is a pulsating pressure at the dipstick hole increasing with rpm.
I did watch the video on this problem but wasnt really able to get the pressure loss at the cap you discribe.

Somehow I dont think this sounds good..


Damon

[Service Dept Vic]

My wife, Service Department Char, recently read a few of my posts and thinks I blabber on too much. So I'm going to try something I don't do very often here on Orangetractortalks.com, and that is to give a two word answer:

Frost Plug!

[finchrat]

Ill start dissasembly tomorrow and report back.
I truly hope that is what it is!

Damon

[Service Dept Vic]

Start by looking at the plugs in the head first. Pressure up the radiator to 15psi max and soap up the sides of the head where they meet the block, look for bubbles.

[finchrat]

Ok I did those tests. No bubbles at all around the head/cyl area under pressure. The glow plugs have some fluffy carbon on them but thats all. No sign of oil or water.
Is a compression test in order? Would have done that but I dont have that size adapter for the plug hole. Can get it though.

Once started the tractor idles just fine..nothing out of the ordinary. It is hard to start..much harder than before I had the head rebuilt by the kubota people. WHen it does start it blows out alot of diesel smoke. Once cleared out it runs fine. Its like it piles up in the chambers while sitting.


Damon

[Service Dept Vic]

Pressure test is done through the glow plug hole, you'll need a 10MM adapter if you decide to do a compression test.

Since the head was rebuilt and re-installed are you sure that you followed the correct head bolt torque tightening seguence and spec?

Looking around the bench there, are there any parts and pieces left over from your overhaul? Some of the head bolts may be "wet holes", in other words they tighten into either the oil galley or the water jacket. Did you notice if any of the head bolts when you removed them had a "white" looking sealer on the threads?

Did you put the head bolts back in exactly where they came from? did you install a new head gasket?

The smoke that blows when you do start it up, is it "white" at first, and then clears, or is it black, like a locomotive under load?

Did you have this water in the oil situation before you peeled off the head?

What event or diagnosis had you rebuilding the cylinder head?

Did you have anti-freeze in the coolant, block and radiator while the head was being done? If so, did you leave it outside or inside a shop?

Usually if the block cracks, something else cracks as well. The water neck at the thermostat housing, the rad splits. Do you see any signs of that?

The oil/water issue may have more to do with the original cylinder head repair/re-installation than a block that "just cracked".

We'll get that Kubota fixed!!

[finchrat]

Wow I know I must have got some of this right :)

-The reason for rebuilding the head was this oil in the radiatior problem. I noticed it blowing oil STRONGLY out the overflow tube. Thats what got all this started. Talked to the kubota shop and they said most likely blown head gasket. So I took the head off and had it gone through anyway ( they said it was a mess inside) It did the same thing afterwards with the same intensity.. pressure in radiator and oil out the overflow.
-I did torque the bolts in sequence. New gaskets used. Didnt see any white sealer on the bolts that I recall. I could be wrong though.
I did put the bolts back in the right spot. I photograph everything and every step as I dont trust myself. No I didnt save the photos unfortunately.
-The smoke is black/grey and diesel smelling. Takes about 2 minutes after prewarming to get it going and it clears in about 15 seconds. As I said this was a definite change from its previously easy starting.
Could the valve clearance have changed after settling in?
I could have set that wrong too...but like I said it runs like a champ once its started.

-I didnt have any coolant, water etc in the block after head was removed as the lower rad tube was off. Im in california too with the mild winter temps.
- The water neck was not cracked but badly corroded.
- The radiator always leaked. The shop had to recore it.

I cant find an adapter to fit the glow plug hole in my stuff unfortunately. I have 10mm but the thread pitch kubota uses is different. I also have a leakdown tester but again no adapter that will match the thread pitch.
I hope we can get this problem isolated its really bugging me. I havent taken the tractor apart yet in case there are further tests we can do Rechecked the radiatior pressure at 16lbs..holds solid for 3 min or so. Starting the tractor did not vary the pressure at all and I lowered it to 6 lbs.


Damon

[mawest]

Hi Do you have a WSm for the z 650 I need the crank spec,need to get my crank turned. Any help would be welcome, Thanks Mark

[Service Dept Vic]

Sorry, I have all the crank specs for everything except a Z650 in a B7000.

Anyone else???