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  1. #1

    Join Date
    Apr 2004
    Posts
    9
    Location
    SE Kansas
    Tractor
    Kubota B7200E

    Default Engine Woes

    I have a 1986 kubota B7200E with the D950LA 17hp engine.
    It was bought last year with 740 hrs on it. When I initially looked at the tractor, I started it up and a very small amount of White/Black smoke was noticed but I checked all the obvious areas you would check for oil in the water or water in the oil. Nothing was out of the ordinary. I just chalked it up to sitting for a while.
    As time went on,the smoke became worse upon start-up. But the weird things were ,it didn't always smoke on start-up and it always cleared up withing minutes of start-up if it did smoke.
    I decided to take my injectors in for rebuild. The guys at the shop told me 2 things. I had water in my center cylinder ( the center injector tip looked like a mine field)and the 2nd was my center injector had gotten so hot the tip had turned a nice shade of blue. I guess this means I was dumping alot of fuel in the cylinder. I tried to find a compression checker but could not find one that went up high enough for a diesel. I did turn the engine over and the center cylinder sprayed water like a fountain. I tried blowing the cylinder out
    with an air gun but it didn't seem to help so off came the cylinder head.
    When I got the head off and turned it upside down, it looked like someone had taken a pin punch and went to town around the valves of the center cylinder. The top of the piston #2 is just as pretty as the other two and the cylinder walls are not bad at all. I don't think anything solid has been in there knocking around so it must be water.
    I filled the water jackets with water last night and did not see any water seeping into the cylinder this morning. The head gasket, did not show evidence of water seepage but I don't have any experience at reading head gaskets. I don't have the time to tear down the engine all the way so I am looking for another way water can be getting into the cylinders. Any help would be appreciated.

  2. #2
    Super Member JerryG's Avatar
    Join Date
    Apr 2000
    Posts
    7,232
    Location
    Northwest Arkansas
    Tractor
    MF 1440-4 PowerShuttle

    Default Re: Engine Woes

    Take the head to a engine shop and have it magnufluxed. That will tell you if it is leaking water through a crack under pressure.

  3. #3
    Platinum Member
    Join Date
    Jul 2003
    Posts
    594
    Location
    mid-south idaho
    Tractor
    Kuota L3130, Ford 9-n, Allis AC, and a JD 4020 with powershift

    Default Re: Engine Woes

    The other way to check is to have the block and head put under pressure and "hydrotested" which will show if there are leaks in places the magnaflux might miss, although magnafluxing is very good at finding cracks.

    Dane

  4. #4

    Join Date
    Apr 2004
    Posts
    9
    Location
    SE Kansas
    Tractor
    Kubota B7200E

    Default Re: Engine Woes


    Can the hydrotest be done while the rest of the engine is still installed in the tractor frame?

    One other question. I have never been able to catch the water recirculating in the radiator no matter how hot the engine becomes. I actually took the thermostat out put it in a pan of boiling water and it did open up so the thermostat is ok.

    The water pump does not appear to be bad. Impeller is not damaged. Not much else to check in my opinion.

  5. #5
    Gold Member
    Join Date
    Sep 2002
    Posts
    411
    Location
    So. Colorado
    Tractor
    Iseki TS1610F 4x4

    Default Re: Engine Woes

    At the point you're at, I would do as has been suggested and have the head looked at and get a valve job done w/ new valve stem seals. Then I would install a new head gasket (and hope it was the head gasket that was leaking, although you should see a tell-tale track from one of the water passages to the cylinder). Then, after all is torqued down, get a pressure gage that reads to, say, 750-psi (McMaster-Carr Supply on the web has them) and put together the fittings you need and take readings at each cylinder. You can connect the gage to either the injector holes or the glow plug holes (which should be easier to find pipe fittings for). This would confirm whether it's fixed or not and wouldn't be too much extra work expended if you found that it didn't do the trick. Then, if no joy, it's engine tear-down time I'm afraid.

    Bill in CO

  6. #6
    Platinum Member
    Join Date
    Jul 2003
    Posts
    594
    Location
    mid-south idaho
    Tractor
    Kuota L3130, Ford 9-n, Allis AC, and a JD 4020 with powershift

    Default Re: Engine Woes

    If you have a good machine shop it is possible to hydrostatically test the block in frame. Many places will bolt a plate on in place of the head and test the block and the head as independant pieces. You will need to check your local shops. Find a good one, ask around who does the best job and talk t them.

    Dane

  7. #7
    Elite Member
    Join Date
    Mar 2002
    Posts
    3,846

    Default Re: Engine Woes

    Does your tractor sit out in the weather with an uncovered exhaust pipe pointing up? Otherwise, you can do your own version of hydrostatic test. Re-install the head, or fabricate a plate in it's place, get a bicycle inner tube, of approximate diameter size of your radiator hoses, cut out a section containing the valve stem and clamp in a hose position, fill with water, pressurize with air to normal rad pressure, 13psi or whatever, and see if it holds, and check for water leakage into engine. Never tried this, but it has been discussed and should work.

  8. #8

    Join Date
    Apr 2004
    Posts
    9
    Location
    SE Kansas
    Tractor
    Kubota B7200E

    Default Re: Engine Woes

    Just as I had susupected. After stripping down the head. I found a crack in the center chamber exhaust seat.

    Now all I have to do is find someone that can weld cast iron or find a good bare head. IF anyone knows where one of these beasts are please let me know.
    The casting # is KT2 D89 3627 S.

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