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JD 455 Transmission Boiling need help

4082 Views 3 Replies 3 Participants Last post by  Mark777
Hi- i have a john deere 455 lawn tractor. I started noticing the problem when i would be cutting grass and the mower deck would stop, but the pto light is still lit. I then checked the level of the transmission fluid, and the fluid was boiling. I changed the fluid and the filter, and it is doing the same thing.. any thoughts?
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Welcome to the forum fixitjoe! :)

Maybe a brake hanging up or a bad bearing somewhere putting a lot of continuous load on the system? :confused:
I was not familiar with that tractor so tonight I looked it up at JD Parts. Looks like the engine radiator doubles as an oil cooler for the tranny and hydraulics? If so, if the engine is running on the hot side that would also heat up the tranny oil. Seems I do recall some mention in the past on forums of the radiators having a habit of plugging with grass on some models.

Might be something else to check if you have not done so already.
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Hi Joe, and welcome to MLMF!

I tend to agree with Mark / Ohio about 'chaff' plugging the radiator cooling fins. These models have the incredible Yanmar three cylinder, diesel engine and are tenacious, durable and reliable. But keeping them cool under heavy loads is a must. Even the weight of the engine oil can raise the temperature several degrees - Check this out: John Deere 455 tractor engine information

What you have, is not a typical LT that has a life expectancy of 5-6 years before contemplating the overhaul on other models with gasoline engines...but a diesel that will go decades before the top end might need rebuilding. This is, of course, based on a cool running Yanmar diesel. If it were mine, I would check all the hoses, belt tension, thermostat (if so equipped) and air way passages to make sure something isn't causing the problems.

Good luck and let us know what you find.

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