JD 855

[Stevo5]

Looking for some advice. Bought a JD855 about 1 yr ago although it was a bit smokey started ok and ran ok until I put a rotary hoe on it.engine ran hot. has has been very hard to start since. Lots go smoke coming from breather hose (greyish smoke). doesn't use a lot of water have topped up oil a couple of times but doesn't seem too bad. I did run it out of fuel one time and I bled it. I'm planning to drop it off to a John deere shop, but very nervous at the potential cost of repair. Any advice much appreciated here

 

[bmaverick]

This has a YANMAR engine correct. Your best source of info should be the Yanmar section here on TBN or on the YTOG.

There are ways to remedy the problem without extreme costs like an upper end engine rebuilt in the thousands of dollars.

 

[gengine]

I hate to say it, but what you say, my gut tells me you have a loss of compression. Could be as simple as rebuilding the head, but my gut says an injector failed, and burnt a hole in a piston. Some of those Yanmar engines had a crank pulley that was actually a clutch, so to speak. Eventually they slowly start failing, so you lose the speed needed for the fan and the water pump to keep up with demand, creating your over heating, which may be a blown head gasket.. A bad injector can also do this when it fails. Instead of the injector atomizing the fuel, it shoots a stream, creating gray smoke, and eventually burns a hole in a piston. Its also possibly that there has been too much idling of the engine, where the engine wasn't burning all the fuel, so it built up in the piston rings, and when it was finally worked to get hot enough, that fuel started burning, which melts the top of the piston, creating your exact symptoms. You may be looking at an engine rebuild.

 

[bmaverick]

How to keep the soot and smoke away and ways to prevent having the head warp and crack on these Yanmar engines.

- Do not let the engine idle below 1200rpms for longer than 10mins max at a time. And the time is with 1hr between.
- Do use 10W30 summer and 5W30 winter for engine oil. Do not use the heavy thicker 15W40 as it will hold the heat longer in the engine. Yanmar makes engines to JIS standards, not SAE. So the cooling oil passages are narrower in metric.
- Do keep the air intake filter clean. A clogged filter makes the engine work harder and heat builds up within the engine.
- Do keep the radiator and the screen clean.
- Do check the coolant. Do not use extended life coolants in these vintage machines.
- Do start the tractor slightly above idle.
- Do not race the engine from slow to fast and fast to slow.
- Do slow the engine speed down gradually, idle for 15 seconds then turn the engine off.
- When parking and doing the engine shut-off, be on level ground, take and place the gear in neutral and if equipped, the PowerShift in neutral.
- Diesel engines, especially the 2-clyliner types will cause a lurch-back on the last 2 piston firings. To prevent the energy going to the drivetrain, be in neutral.

Some of these tips are from Deere, some are in the Yanmar USA bulletins and some came from the Yanmar JP website before 2018.
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