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.

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, 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.
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, so I assume the heater is working.
3. Confirmed that the fuel stop solenoid activates upon start up and releases upon key turn off.

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.

 

[beenthere]

Welcome to TBN
Help from the knowledgeable members will be along in due time.
Sure sounds fuel related, but I'm a novice to help further. A decayed fuel line or some stray dirt would be my suspicion. Hope you get it back to the normal quick starts.
Which Yanmar model engine?

 

[Roadworthy]

Check the air cleaner and path from there to the intake manifold. An inadequate volume of air will cause black smoke due to incomplete combustion.

 

[MTGreen]

When if ever have the valves been adjusted?

 

[D&D]

Load test the battery, slow cranking speed can cause Headaches too.

 

[Harry in Ky]

Next time you go out there try the air heater again, only this time put your hand on it. Hopefully you can reach it and the key at the same time. With power applied you should feel the area around the heater start to get warm after twenty seconds or so. You know the circuits work but you don't know (yet) if the element itself works.

 

[Hillwalker]

Answering Q's in-line below:

1. Engine model: Yanmar 3TN75RJ 1.0L diesel
2. Battery: I forgot to mention I replaced the battery first with a new one as I thought that was the problem
3. Valves: Unclear when they were last adjusted
4. Air cleaner path: Will check and report back.
5. Air heater temperature: Will check and report back.

 

[Hillwalker]

Reporting back that the air heater works and air clearer path seems clear.

 

[Harry in Ky]

I think you've pretty well covered the basics. I do question the part about black smoke while cranking. I must assume it never did that when it was starting better? Typically when attempting to start diesel engines the smoke is grey while cranking. What is your memory on that from past usage?

 

[Hillwalker]

Well, I just tried it again and it took 4 tries to start it and lots of black smoke. But once it had been running, I could turn it off and on at will no problem and the smoke seemed normal. If I wait a few hours, it probably will be hard to start again with the black smoke.

Does this sound like fuel de-priming to you? Again, I changed the fuel filter....so is it cranking a lot to pull fuel back into the system? I just bled it at the fuel bowl and pump again but still have not tried bleeding at the injectors as the instructions seem a bit unclear to me.

 

[Harry in Ky]

Fuel de-priming? I'm not sure that's a word, but I don't think that's the case here either. Did you change the filter BEFORE or after you attempted to start it this last time? Personally, when given the choice I never change fuel filters on a cold engine. I always start and run it for a few minutes, shut it off and then change filters. Engines always seem to start better the second time around and the system is all primed, injector lines are charged up, and all that.

If it were actually "de-priming", the first attempt to start it would produce no smoke at all, or just a few puffs then go away entirely before coming back and eventually the engine starts. I doubt that's the case here, or is it?

As for bleeding the injectors, my experience has been where that only becomes necessary when the engine won't start at all due to lack of fuel in the injector lines. (for whatever reason) If it starts and runs at all, then bleeding injectors is USUALLY not needed unless there is a pump problem. That's not a typical concern with this style pump. I'm not a pump specialist so that's a personal observation only.

 

[D&D]

Well, I just tried it again and it took 4 tries to start it and lots of black smoke. But once it had been running, I could turn it off and on at will no problem and the smoke seemed normal. If I wait a few hours, it probably will be hard to start again with the black smoke.

Does this sound like fuel de-priming to you? Again, I changed the fuel filter....so is it cranking a lot to pull fuel back into the system? I just bled it at the fuel bowl and pump again but still have not tried bleeding at the injectors as the instructions seem a bit unclear to me.

How cold is it where you park the tractor?

 

[gstrom99]

Welcome. I bump the throttle up a little, whenever I start mine, especially when cold starting. If I leave it at base idle, it is not happy. I've always had some black smoke at startup. Once it (yours) is/has been running, there's really no point in bleeding it more - unless there is a cracked/leaking line (filter seal?) somewhere letting air in.

 

[MTGreen]

I'm leaning towards it not being a fuel problem. Black smoke means too much fuel.
Since your preheater works, the tractor runs fine once it starts so that rules out injection pump timing or gross injection pump problems, that leaves compression or not spinning fast enough while cranking.

From my perspective you should adjust the valves -always makes a noticable difference with starting easier, starts at lower rpm, and quiets the engine down as well

 

[Hillwalker]

@Harry - I changed the fuel filter in September and this problem just started in November/December
@D&D - It is 32 degrees at night and 55 degrees in the day time here
@grstrom - Yes, I've tried multiple throttle positions
@MTGreen - It does seem like it is not spinning fast enough, that's why I changed the battery. Even on the fourth try, have to use the starter to help it spin faster (Hold it for too long, frankly). Is adjusting the valves something that a layperson can do with the manual?

 

[MTGreen]

Starter speed is voltage dependent and assuming a good battery voltage is resistance dependent. You could try to minimize resistance by wire brushing both ends of both battery terminals and reconnecting and verifying that you have a solid ground to your starter by running an extra ground cable to your starter mounting bolt (not the + battery connection lug).

Adjusting the valves is simple with feeler gauges and a wrench and socket set.

 

[Hillwalker]

Got it, I will give both of those things a try. One more question: If the valves are out of adjustment, is the thinking that it would be creating too much compression, which is therefore slowing down the starting speed?

 

[D&D]

Got it, I will give both of those things a try. One more question: If the valves are out of adjustment, is the thinking that it would be creating too much compression, which is therefore slowing down the starting speed?

Page 2-119

http://www.wfmfiles.com/download/manuals/CTM3.pdf

 

[D&D]

@Harry - I changed the fuel filter in September and this problem just started in November/December
@D&D - It is 32 degrees at night and 55 degrees in the day time here
@grstrom - Yes, I've tried multiple throttle positions
@MTGreen - It does seem like it is not spinning fast enough, that's why I changed the battery. Even on the fourth try, have to use the starter to help it spin faster (Hold it for too long, frankly). Is adjusting the valves something that a layperson can do with the manual?

Can you park it someplace warm or use a heater before first start?

 

[hosspuller]

Got it, I will give both of those things a try. One more question: If the valves are out of adjustment, is the thinking that it would be creating too much compression, which is therefore slowing down the starting speed?

Out of spec Valves would mean losing compression. Leading to hard cold starting.