John Deere 855/856 hard starting

[Hillwalker]

Hope all is well! I have a 1987 JD 855/856 compact utility tractor that has recently begun to be very hard to start first time in the day. It has 923 hours on it and a known history back to 2001-ish and has always been maintained well. It has the Yanmar 3TN75RJ 1.0L diesel.

The tractor was used all summer for some general property upkeep and then I elected to do a full service on it in September of this year where the hydraulic, oil, coolant, and all filters (including fuel) were changed with all JD parts and JD fluids.

Current behavior is that first time in the day it will take nearly 4 attempts to start and it will blow a lot of black smoke while it is cranking. Once it has been started, it will stop and restart at will even if not fully warmed, unless around ~2 hours elapsed. Current weather is 58 degrees and it just exhibited this behavior again after resting for a few hours.

My suspicions as to root cause are either fuel-related or heat-related (32 degree nights versus 80 degree nights over the summer).

Here is what I've tried so far:
1. Using the tech manual, I have bled the fuel system at both the bowl and pump and did not see any bubbles. Have not yet progressed to the injectors as the instructions are a bit unclear.
2. Bought a test light and confirmed power at the preheater grid (this unit does NOT have glow plugs) when the light is on the dash and I also confirmed to the touch that the pre-heater is working.
3. Confirmed that the fuel stop solenoid activates upon start up and releases upon key turn off.
4. Replaced the battery with new.

This tractor has had a history of effortless starts up until now and I'm hopeful I can restore that. Thank you in advance for any and all tips.

 

[Dan in Ohio]

I have a later progression of the 855 CUT, the 2520, at least I think it is a newer model. The 2520 has several diodes in the electrical system that can reek havoc that are referred to as V4 diodes. They can and have caused many of us to battle problems similar to what you are having. I am going to recommend another site that has dealt with this problem extensively and mean no disrespect to this site. Maybe they can help you as they have others. Click below.

GTT

 

[bmaverick]

Hope all is well! I have a 1987 JD 855/856 compact utility tractor that has recently begun to be very hard to start first time in the day. It has 923 hours on it and a known history back to 2001-ish and has always been maintained well. It has the Yanmar 3TN75RJ 1.0L diesel.

The tractor was used all summer for some general property upkeep and then I elected to do a full service on it in September of this year where the hydraulic, oil, coolant, and all filters (including fuel) were changed with all JD parts and JD fluids.

Current behavior is that first time in the day it will take nearly 4 attempts to start and it will blow a lot of black smoke while it is cranking. Once it has been started, it will stop and restart at will even if not fully warmed, unless around ~2 hours elapsed. Current weather is 58 degrees and it just exhibited this behavior again after resting for a few hours.

My suspicions as to root cause are either fuel-related or heat-related (32 degree nights versus 80 degree nights over the summer).

Here is what I've tried so far:
1. Using the tech manual, I have bled the fuel system at both the bowl and pump and did not see any bubbles. Have not yet progressed to the injectors as the instructions are a bit unclear.
2. Bought a test light and confirmed power at the preheater grid (this unit does NOT have glow plugs) when the light is on the dash and I also confirmed to the touch that the pre-heater is working.
3. Confirmed that the fuel stop solenoid activates upon start up and releases upon key turn off.
4. Replaced the battery with new.

This tractor has had a history of effortless starts up until now and I'm hopeful I can restore that. Thank you in advance for any and all tips.

It's a Yanmar.

If the engine oil is 15W40, then to crank the engine over, the starter gets weak and wanting to draw more current. Yanmar engines love 10W30 diesel oil summer and 5W30 winter. And the 15W40 will not relieve heat fast enough in the engine, so the heat gets hotter in operation.

Next, The Yanmar engine has an oil pump with alright suction. Using a WIX oil filter cases the pump to work harder and making the starting harder too. Purolator filters are in the right micron rating for Yanmar machines. 26 - 38 microns.

BTW, on several other tractor sites, people are moving away from the Deere OE oil filters. They are now smaller, cheaply made and now cost more. Some insight here, https://www.greentractortalk.com/threads/the-new-smaller-m806419-oil-filter.226738/#post-3991593

Do not let a Yanmar let any Yanmar engine idle for more than 10mins. Soot builds up atop the pistons and values and all in the exhaust ports thru the exhaust pipe.

Old Yanmar starters were made by Hitachi, Denso and Mitsubishi. These are the solenoid 1.2Kw types. As they age, voltage is applied each time and all, the coating on the windings goes bad. Then the solenoid is not working to its prime. Now, the modern replacement is the OSGR type we find in many of the modern vehicle after 1986.

Ah, your machine has the air-intake pre-heater. A nice device.

 

[buickanddeere]

Plug in the block heater prior to attempting winter starts . This is normal procedure .

 

[dieselade]

I would recheck the orings/gaskets that you replaced during your maintenance especially the fuel filter.

 

[Hillwalker]

@buickanddeere - it does not have a block heater and it never had this problem last winter. live in DFW so winter isn't exactly harsh here

@dieselade - will do

@bmaverick - thank you

 

[Scott 730]

And the 15W40 will not relieve heat fast enough in the engine, so the heat gets hotter in operation.

??? Care to expound on this??

 

[buickanddeere]

@buickanddeere - it does not have a block heater and it never had this problem last winter. live in DFW so winter isn't exactly harsh here

@dieselade - will do

@bmaverick - thank you

Had to google DFW .