JD 755 CUT Governor Issues?

[DrBill]

More details, or links to more details?

Hi there,,, I know this post has sat for a while but it's going to come back up because I'm dealing with the same issue on my 755 and I have the same tenacity as the original poster to solve my governor pains..

I've spent the last two years, ( I travel a lot) remanufacturing my engine and radiator to fight and stop an overheating problem. During this time I've enjoyed a governor that was anything but...

I have all the books and technical data that like mentioned,, explain why all design engineers I've worked with have unpaid bills and cars that won't run... All of them..

At my time of rebuild,,, I cleaned and assembled the governor assembly without changing existing settings,, except I did back out the throttle stop screw so I could be my own governor..

I'm going to review this post carefully, and will be adding my comments and questions..

The 755 is a good chassis,, fun to operate, but the engine is too small for its potential as a tractor and has a 500 rpm powerband.. It for sure needs a sensitive governor..I'm going to have one.. Thanks for this thread...

 

[DrBill]

The adjustment explained toward the bottom of page 3 of this post topic by michahicks is correct, as well as his other comments about lack of information available.

Anyone with a Deere/Yanmar that appears to have low response to load should read the information..

It appears the information will hold true for most of the yanmars used by deere, for sure any TN series..

I hope this post will lay around for someone else to find later, as I'm sure someone will be wanting to know..

 

[Fred Sanford]

I'm having the problem and taking the advise here I removed the cap nut--1/2 off in pic.

I see a small bolt/threaded rod/shaft with 2 nuts on it.

It seems to move freely in that larger threaded piece. I didn't dare turn it but it does seem to pull out a bit and feels loose.
I'm confused as to what to do now.
Do I:
1. loosen the remaining large nut and turn the large threaded piece itself out one turn then lock that nut back and put the cap nut on while leaving the little rod and nuts alone?
2. loosen and back off the little nuts on that rod one turn?
I'd greatly appreciate replies from someone who's done this. Thanks!

 

[DrBill]

Fred,,,,, do not mess with the small nuts connected to the little rod... Leave that alone,,, and yes the little rod does move about,,cand all of that is ok......

The process is like you said in choice 1,,,,,, loosen the big nut and turn the threaded "cylinder" (for no better word), out about 3/4 to one turn,,, then tighten the big lock nut,,, and put the outer cup back on...

The end result of this is the governor should kick in faster and also allow the pump to deliver more fuel..

You can tell if it worked right away with more power and overall behavior..

Let me know how it goes
B

 

[DrBill]

I just now looked at the photos posted by Fred.. The big threaded piece shown in his photo is definitely screwed in too far. Based on what I'm seeing I think i would suggest maybe turning the big threaded piece out maybe 1 and 1/2 turns or possibly more.

It will be ok to trial and error this adjustment.. Back out and try,, then if needed or desired, back out some more.. If you get too much smoke at full power and start chocking out with too much fuel,, you know you went too far, and screw it back in some !

Because of work, I'm not near my tractor, but when I get home next week, I'll do an exposed thread count to see how far mine is backed out..

 

[Fred Sanford]

Dr. Bill,

Thanks a bunch for the quick response. If it's not raining tomorrow AM I'm going to turn the cylinder out 1 turn and see how that does--if you have an opportunity to check how many threads are exposed on yours I'd appreciate it but I don't want to inconvenience you as I can play with it a bit. I was just scared of messing up something delicate and important. This is the first diesel I've owned/worked on.

 

[DrBill]

Fred, On the topic of this being your first diesel, it can be tricky to adjust your thinking to the different quirks the diesel can have. There are thousands of posts here about the importance of clean fuel and unclogged filters and lines. Keep that in mind while working on your tractor, especially if nothing you do or adjust creates a positive change.

On your yanmar, remember it's running wide open from an air intake point of view all the time. Make sure your air filter is good, and that's about all you can do for air.

The only thing that controls rpm or power is the amount of fuel delivery. When you work on your tractor the first thing to check is free rpm. This means when warmed up for a bit, push the throttle wide open with no load.

If it's a something 55 tractor, The rpm should max out around 3200 to 3600 max. There is a separate adjustment for that if needed and I won't go into that now, but it has nothing to do with the governor adjustment we are talking about here. But, it is important to know about because if you don't have enough free rpm, that would need to be considered first.

Now, the governor adjustment will not affect maximum rpm. What the adjustment will do is allow the amount of fuel necessary for the engine to try and maintain the rpm you have the throttle set to for whatever job you are doing.

Also, keep in mind that your diesel will have a narrow power band compared to gas engines. If your yanmar is a 55 series, this range for making useable power will 2200 rpm plus. For mowing, throttle up to 3200..

Good luck with everything..
B

 

[Fred Sanford]

Dr. Bill,

Thanks for all the help. I caught a few minutes this AM as it began misting and turned the barrel out 1 to 1-1/8 turns. I'd driven it down the road to pull a neighbor out a snowy ditch a few weeks back and it'd bog down going up hills and I'd throttle up and as I topped the hill and started down the other side it'd sound like it was going to run away. Today with the loader on for weight I put it at 3/4 throttle, full forward on the hydro in high range, and set the cruise control. Headed up the hill with almost no change in engine noise (no bogging, it really didn't act like it had encountered a load at all--no smoke or sound like it was working hard either). I also couldn't see where travel speed slowed any either. It might well be fixed--I'll need a bit more time in good weather with it and some real loads to test further. If real work causes it to bog I might unscrew it 1/4 more of a turn and try that.

Now if only we had that quick of a fix for the paint coming off in sheets. Well, that'll be a rattle can for me as it comes off I guess.

P.S. This is the first diesel I've owned and had to work on, I've operated a lot of diesel equipment before. But, I'm also not a diesel mechanic and thus my hesitation to get into a supposedly non-maintenance item like the governor. Before I started searching the web for answers I'd drained the fuel tank--it was clean except for the fuel inlet screen and several inches of pickup line which was disconnected and laying at the bottom of tank (no wonder it ran out of fuel with the gauge reading 1/4 full )--now it's installed and clean. I replaced the fuel filter, bled the system at filter then the injector pump, replaced the first stage air filter cartridge--the second stage looks mint, and the inlet hose was clear. The tach is broke and I don't intend to fix it.

 

[DrBill]

Fred,, glad to hear you got a chance to adjust some. It probably did help. I've had some PMs and emails on this subject several times over the years. About 7 out of 10 times it worked. The times it didn't were bad fuel lines and fuel in general. When I started on mine, my tank and pickups were so bad the screws broke off just trying to get the pickup lines out. I got so frustrated I bought new tank and all related parts, and that was before I knew if the tractor was actually any good or not !

In spite of our good exchange, I actually don't hang out here much. However, I do get an email anytime someone responds to this thread. I did so in case someone else needed info. I hope for sure that yours is another case where it helped..

PS,,, your tach problem is almost always a cable and fairly cheap and easy to replace.
Best Luck,
B

 

[Fred Sanford]

Thanks, it was so nice to find this thread and see other folks had the same problem. I really appreciate your replies. Hopefully my pics and your comments will further help the next person who has this problem.

For the next readers who find this thread: Dr. Bill is right that you need to check fuel system top to bottom before assuming it's the governor. They are strange beasts when they get air in the system. I know my tractor started loosing power on a slight hill shortly after I got it. After a bit trying to figure out what was going wrong I started to suspect it was low on diesel and the gauge was wrong. I added a couple gallons to the tank and bled the system. It would then start but it still did not have enough power to even drive. After sitting a couple hours while I thought things over I looked and 1/2 the fuel filter was full of air. I bled again and it was fine. With an electric fuel pump between the tank and bleed screws if it starts sucking air it apparently churns it into such a froth it takes awhile to settle out and come to the top so it can be fully bled--or so it was for me. I also found it sprays diesel everywhere when bleeding. What a mess and dead grass too. Plus if your tractor has diesel in the tank and is still getting air in the lines--remember my intake screen and the hose that connects it to the pipe leading out the tank had come loose and was just laying in the bottom of the tank thus the effective intake was several inches above the bottom of the tank--your might have too--my gauge was correct. I found this out later as I was checking everything before pursuing the governor adjustment. I took the hood off then the sender unit off the tank, siphoned out all the diesel and inspected inside with a flashlight.

PS I hate to get the thread off topic here for future readers but I'm betting it's the tach itself as the needle spins in circles constantly when running. I'm assuming the tach cable is spinning or it wouldn't do anything. Not going to worry about it now.