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  1. #1

    Default John Deere 750 Head Gasket Gone Again

    OK guys my dads friend has a john deere 750 with the 3 cyl Yanmar diesel with 800 hrs and like 25 years old. About a year in a half ago it puked out collant we tested the radiator for exhaust gases. Came back positive. SO we had pulled the head off and when we had pulled it off the last cylinder closest to the steering wheel was filled with antifreeze. We had started to inspect the head and it had cracks in that cylinder so we had went ahead and bought a new head for it witch was like 700 and some change along with new head gaskets and stuff. The other day he was using his bush hog and it had puked out antifreze agin and then stoped running cause one cylinder has filled with anti freeze. Now could have the head bolts strected due to that they were the old ones or what just trying to get a idea on why it blew the gasket again and maybe the head but not sure till we get the tractor to work on it. Also it happened when he was bush hogging the first time and did the same thing again. Any ideas would be helpful Thanks.

  2. #2
    Elite Member dfkrug's Avatar
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    Default Re: John Deere 750 Head Gasket Gone Again

    Did you check the block deck for flatness and cracks, or corrosion pitting?

    As for the head bolts, sure, proper torqueing is required, starting from the
    center of the block and moving outward. Some manufacturers call for
    re-torquing after the engine has been running for a while, but the reality is
    that virtually no new engine undergoes re-torqueing. I assume you did
    the initial torqueing correctly....they only take about 65-70 ft-lbs. I never
    buy new head bolts myself, though on some modern engines, new bolts
    are required because the stretching ruins them for re-use.

    Sorry to hear of your troubles.

  3. #3

    Default Re: John Deere 750 Head Gasket Gone Again

    Yes had went back with the factory head torq. No cracks or corroding on block. Head and black was stright had got a edge from are race engine builder to make sure before we put it back on. Could a cause be that the radiator is not getting good flow due to old age and getting hot and pushs the gasket.

  4. #4
    Elite Member dfkrug's Avatar
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    05 Kioti CK30HST w/ Prairie Dog backhoe

    Default Re: John Deere 750 Head Gasket Gone Again

    Quote Originally Posted by woodduck97 View Post
    Could a cause be that the radiator is not getting good flow due to old age and getting hot and pushs the gasket.
    You may be onto something. When you are starting to overheat, the
    cylinder farthist from the radiator will get hottest and fail first. That
    assumes flow is not compromised to one cyl more than another. On my
    older Yanmar engines (1996 vintage JD955), I notice the water passages
    are not very big, while the newer one (EPA tier 2) has much bigger water
    passages. On yours, can you see well enough in the water passages to
    verify no serious blockages or rust build-up?

  5. #5

    Default Re: John Deere 750 Head Gasket Gone Again

    Well we havnt had time to tear into the engine yet but thats the only other thing we can think of. But I do know when we get it off this time we are going to be cleaning passages if needed in the block and checking the radiator and if a lil stoped up its geting a new one.

  6. #6
    Super Member Scooby074's Avatar
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    BX 25, ZD 326

    Default Re: John Deere 750 Head Gasket Gone Again

    I probably would have changed the head bolts. Cheap insurance. Alot of bolts once torqued wont hold torque again.

    Overheating could have caused some issues. Did anybody notice if it was overheating before these problems?

    And your sure you checked both the block and the head in several places? Front to back, side to side, and corner to corner for flatness? Some just throw the straight edge down the centerline of the block and call it flat.

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