Help! Slight knock in bison II.

Thetester

New User
Hey guys, I've lurked around here for a couple years mostly finding answers to a lot of my tractor conundrums.

I find myself back to ask a few more. I recently got a bison II 25 hp diesel tractor basically free. When I got this tractor it had water in the tank but the fuel line was not attached to the pump. It had sit for a few years never cranked.

The plungers were stuck. I did unstick them with light tapping of a brass rod. I am a master machinist and understand tolerances so I did nothing more than wipe them with solvent, oil then reinstall.

The tractor is a two cylinder as I had not mentioned. I had to pull the tractor off with a truck as I suspect the rings were lightly stuck in the pistons. At first I had tons of blow by but after five mins of run time it is basically steam from oil fill.

It starts and runs well with no smoke. However the exhaust is mildly warm to touch after five mins of runtime.

My question is this, it sounds like I hear a slight knock toward the front cylinder. very faint.

What exactly would you all do to make sure this tractor is field ready.

How would you inspect the knock?

Since the plungers were stuck maybe the knock is pump timing?

It is hard to get parts for this tractor so I want to make sure I don't overlook and do something entirely stupid and end up with trash. I do what I have to based on risk reward and worth of the ole tractor but would like to get it to work in the field.
 
The knock could be caused by an uneven spray of diesel, but I would expect it to be a bit uneven at idle.
 
Yes it seems to go away mid throttle toward full throttle. At least it seems to hush up to where I can barely hear it.

Is there a fix here? The plungers are adjustable on the rack. I am saying this as maybe the fuel delivery could be altered.
What's the best way to confirm this as the prob??
 
I am not an expert on that engine, but have heard the knock at idle when injection is not even, others will pipe up.
 
Thetester,You might double check the injection pump timing to be certain it is correct for that engine.
 
See this tractor "import" don't really have manuals that can be found. If so they are prob in Foreign. I'm not even sure how to slightly adjust this pump timing.

I can post pics would this help discern if I can helped on this matter?

I keep thinking of the uneven injection comment. Are you talking uneven crack pressure of the injectors, uneven delivery from the plungers or the injector timing??

Could the pump be slightly tweaked without indicators to measure to the thou or am I gonna have to get specs on this thing which is impossible?
 
(quoted from post at 22:22:05 03/02/15) See this tractor "import" don't really have manuals that can be found. If so they are prob in Foreign. I'm not even sure how to slightly adjust this pump timing.

I can post pics would this help discern if I can helped on this matter?

I keep thinking of the uneven injection comment. Are you talking uneven crack pressure of the injectors, uneven delivery from the plungers or the injector timing??

Could the pump be slightly tweaked without indicators to measure to the thou or am I gonna have to get specs on this thing which is impossible?
ou might want to have the injectors tested.
A stuck open or closed injector does sound like a bad rod bearing and yes it can be intermittent and clear up with increased RPM as a proper spray pattern is more critical for start and idle and less noticeable at higher RPMs
 
is there timing marks?can you spill time it to at
least see where on the marks it is injecting?can
you pull the injectors and have them tested for
spray pattern and crack pressure. even if you dont
know specs they should both be the same.
 
Everything on this thing looks to be dead nuts easy. Everything is adjustable and easy to get to. Very nice to work on but just no literature to speak of to be had.

That said yes I think I will look it over to see if there are timing marks. I think I remember how to spill time. However keep in mind, nothing on this tractor has been altered or tinkered with since I've got it. The tractor was running perfect a few years back when the lifting mechanism broke. It was parked and abandoned where it sat.

Now i did tapp the plungers loose as I said they were stuck and reinstalled. I'm sure they are back EXACTLY as they came out and I did not effect the quality of the plungers.

It seems to run good with only a couple things to question.. One it is sluggish to catch up if you throttle up quick. It slowly increases engine speed to catch up. Of course the the knock for the second.

What I've tried is cracking the line at the injector. I can't tell by this as it's a two cylinder and it wants to stall if I do. It does show both cylinders are firing and chuggin.

Please tell me about the ATF in the fuel?? How much to fuel ratio and what might this cure ?? I've heard of it in oil to prime up old collapsed lifters in gasser engines.


It's raining here in bama but I will still try to spill time and report back. I will also upload a short clip of it running if you all care to take a look see and listen. Thank you all so far for the help.
 
could be leaking injecter causing slight pre ignition if setting long time may clear up on its own
 
I would not mess with the timing as it was running fine before it set. I think your problem is, like the others have posted, your injectors misfiring or dripping.

Are you using the fuel that was in it or did you drain it and put in FRESH fuel??? I don't care what some say, old diesel will make engines run rough.

Put in fresh fuel. Add a quart of transmission fluid to 10 gallons with a full can of Sea foam.
 
(quoted from post at 21:05:14 03/02/15) Hey guys, I've lurked around here for a couple years mostly finding answers to a lot of my tractor conundrums.

I find myself back to ask a few more. I recently got a bison II 25 hp diesel tractor basically free. When I got this tractor it had water in the tank but the fuel line was not attached to the pump. It had sit for a few years never cranked.

The plungers were stuck. I did unstick them with light tapping of a brass rod. I am a master machinist and understand tolerances so I did nothing more than wipe them with solvent, oil then reinstall.

The tractor is a two cylinder as I had not mentioned. I had to pull the tractor off with a truck as I suspect the rings were lightly stuck in the pistons. At first I had tons of blow by but after five mins of run time it is basically steam from oil fill.

It starts and runs well with no smoke. However the exhaust is mildly warm to touch after five mins of runtime.

My question is this, it sounds like I hear a slight knock toward the front cylinder. very faint.

What exactly would you all do to make sure this tractor is field ready.

How would you inspect the knock?

Since the plungers were stuck maybe the knock is pump timing?

It is hard to get parts for this tractor so I want to make sure I don't overlook and do something entirely stupid and end up with trash. I do what I have to based on risk reward and worth of the ole tractor but would like to get it to work in the field.

Could you take the injector lines off the injectors and slip a piece of clear plastic tubing on each one, leaving the upper end open of course, and hold them vertically and turn the engine over till a fuel level appears in each tube. A difference in column height would indicate an imbalance in fuel delivery. I have replaced barrel/plunger units in the field and successfully set the new plunger delivery to match the others. Not as precision as a test stand where the pumps fire through an injector but close enough to let you know what you are dealing with.

mEl
 
I've never seen a Bison II, but from your description it sounds like it's nearly identical to the S630, Satoh Bull. I had one, very good little machine. Uses a 25hp Mitsubishi diesel, while the Bison (650g) used a Mazda gas engine, also common on some forklifts.
these were made for the North American market, so English manuals are available, at least for the Bull and Bison, Not sure of the Bison II.
For engine work, I'd search for a Bull manual. Looks like several are being sold on the net. Maybe if you used the model number (650, 630 or whatever is on yours) it would help.
I will tell you that the little two cylinder diesels are noisy at lower speeds, but smooth out at working speed. Much more noise and vibration than the later 3 cylinder versions from Mitsubishi, and Yanmar.]]

As others have stated, use the additive of your choice, ATF, etc.. Then work it, not just run with no load, but really work it, get it up to operating temp and run for awhile.

I'll bet it gets better.
 
I would like to thank each one of you have tried to extend help to me!! It's hard to find folks that are willing to extend advise and knowledge without compensation. Again thanks!!

To follow up it's I am neither lucky or fortunate in this situation. I just didn't feel like trusting what I heard after I cranked the engine up today and ran it for ten mins or so.

I took a wood pole and stuck it to my ear and prided the motor like a stethoscope till I found the knock. It was coming from the top rear of the valve cover.

GOOD THING I TOOK OFF THE COVER. No oil to the top. I never noticed the oil pressure was low. It is a weird gauge and figured it up to be old and flawed. I was getting about ten pounds converted.

Don't look like I can pull the pan without splitting the tractor. So I took off an access plate on the side and found two pcs of bronze bearing type stock. I have NO idea what or where it came from. I found two small nuts and a broke set screw.

One rocker are had over 1/8th inch clearance.

HOW THE HELL THIS THING RUN I HAVN'T a clue. Ran great though!!

I will share pics. Please tell me what you think these parts are and what you would do to investigate further.
 

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