755 issues

[DrBill]

I hope you end up with a solid tractor too.. I finally got a sturdy 755 but when I was getting mine going I read a lot about overheating, cracked heads and blocks, and low power issues...

Working on your fuel pick-up, I'm sure you noticed how packed in the radiator, oil cooler and fuel tank are in the front of the fan.. This has been reported by many, including dealers, as the eventual downfall of this series...

As you are fixing things, keep this in mind and keep the radiator, screens and all fins as clean as possible. If the plastic fan is worn, chipped or cracked anywhere,, replace it.. The total capacity of the cooling system is only 1 gallon, so with the above issues it's even more important to keep the coolant clean with no buildup inside the radiator..

After this, the next thing that completely changed my 755 and others too, was a governor adjustment. A lot of owners had complained over the years about low power. There was no information about how to adjust the governor or get more fuel. To date there are no TN engine manuals published by deere that cover this issue..

If you want to know about this, go to 455 quirks in deere lawn/garden forum,, and go to the last pages and you will find where beenthere and myself discuss this, and links to prior posts about it..

I wish you the best with your tractor..

 

[Mechanos]

...Working on your fuel pick-up, I'm sure you noticed how packed in the radiator, oil cooler and fuel tank are in the front of the fan.. This has been reported by many, including dealers, as the eventual downfall of this series...

I wouldn't extend this downfall to the entire series... just the 655, 755 and early 855. They moved the fuel tank to the rear of the engine early on in the 855 and it stayed there in the 955.

 

[DrBill]

I'm glad you mentioned the tank move because it shows that deere themselves saw the problem, and all the more important for us with the front mounted tank to be aware of the previous warnings..

Early on in my tractor build I considered moving the tank but could never come up with an idea that I felt safe with.. I did buy a new tank and pick up. When installing I noticed the new tank was shaped slightly different on the top half that gave a little more air gap behind it.

Did deere do this on purpose ? I don't know.

I also bought a new fan, and I noticed it had more pitch than the old one.. Did deere do this on purpose ? I don't know that either..

I rebuilt my own water pump, but I noticed that deere had changed part numbers on the replacement pump I had looked at first...

I'm just mentioning these subtle findings as it seems as if deere had taken some steps to improve this situation.. I would also like any new 755 owner to know some of it and not have to stumble upon all of it the way I did..

 

[wheeler01]

I have been reading about the cooling issues with them. I drained and flushed the radiator already. Ive notice that during operation there seems to always be a bit of coolant that spits out the overflow tube, even after changing the coolant. I just assumed it was normal since theres no overflow bottle on it.
And I also noticed how dirty and gimey the oil cooler was upon removing the tank. I cleaned it ou. The screen infront of the radiator was clean though. Everything got a good bath in degreaser, so hopefully itll stay a little cooler. It is a pretty poor design.
As far as the governor, I havent been brave enough to mess with it yet. I found a thread on a few days ago and read up on it. A lack of power is actually what caused me to tear into this thing. Seemed like it would bog down alot under load and smoke. I had a leaking elbow on the input side of the fuel filter housing, where the hose attaches coming from the fuel pump. It was leaking fuel bad around it, the previous owner had just put a zip tie around the elbow and filter housing to hold the elbow in. Lol. I figured this problem might have been causing the loss in power under load, but after researching, seems there could be other issues, which led me to draining the tank and looking into the pick up screen problem. I haven't had a chance to put it through the paces yet, after replacing the filter housing and cleaning the tank/fixing pickup screen. I hoping it will respond better. It seems to be revving better and not bogging down while using the loader, so im keeping my fingers crossed. I have some tilling to do this week so that will be the next test. The first time I ran the tiller with it, it didnt like it. Lol. Hopefully it goes better this time, if not im going to try the governor fix. Thanks for all the help and suggestions. This is my first tractor, bought it do small food plots, snow removal and odd jobs on the side. Just trying to get the quirks worked out.

 

[DrBill]

Wheeler01,,, I'm glad to hear that you saw all of this.. On a positive note it seems these tractors are one tough cookie once straighten out and the operator knowing what to watch...

I haven't heard from anyone who had a negative experience from the governor adjustment,, but it won't hurt to wait on it.. Just knowing about it is the main thing... When you start loading the tractor, start listening for the governor to kick in... When it does you will know.. If the engine is in decent tune, it kinda sounds like a old 4 barrel carb opening up ! (For no better words).

It seems a lot of these yanmars were set on the safe side and basically never opened up at all, or did so around 2000 to 2400 rpm,, and it was too late then as the engine was already off the pipe.. (Power curve)

As you might have already read,,, mine is now set to start working at any load that tries to pull it lower than where I have the throttle set... Even idle. (1500). And it's a completely different tractor than at any time I've owned it.

It also runs cooler than before... I think that's because it's not running in a constant bogged down condition..

 

[wheeler01]

One reservation I had on the governor screw, was I didnt see any witness marks on the nut, so I wasnt sure if some had already messed with it. I just didnt want to adjust it further and cause any issues. Is it possible to over adjust it?
Also, my fuel filter housing is in the way of the acorn nut because I had to mount it canted a little because of how close the corner of the battery tray is to the elbow fitting. I believe thats how the elbow broke free on the original housing. Almost like there should be a spacer between the filter housing and the mounting plate that bolts to the engine. Doesnt seem like theres enough clearance once the engine is running and vibrating. Ill attach a pic to better explain. I circled the in yellow the area that doesnt have enough clearance. Blue is the acorn nut that deals with the governor adjustment correct?

 

[wheeler01]

Pic didnt attach first time.

 

[DrBill]

I'm guessing, but I'd say no one has adjusted it before.. Yes,, the item circled in blue is the correct place.. Underneath the cap nut is the hollow threaded piece.. Actually the cap nut screws onto this threaded piece that is adjusted...

Could it be adjusted too much ?,,, well I don't know.. However, if you think your governor is not responding good enough,,, one turn counter clockwise at a time should be safe, and that's the same or less than anyone else has done... If for some reason you got a negative response,,, it could easily be turned back in where you started from...

I did have my governor apart, at the time I didn't mess with this screw because I didn't know about it..

It's actually just a limit bumper that limits the pump arm movement in the open (more fuel) direction of movement...

It's not something where a bunch of springs and balls are going to fly apart, or the governor break or quit working... The worst could happen I'm thinking would be too much fuel...

When I turned mine out, the only thing I worried about was if it was out too far, the cap nut might bottom out and not seal against the lock nut when I put it back on... (More threads sticking out that the length of the cap nut). I guess that could happen,, but it didn't in my case..

Like you said before,,, you can wait and see how the tractor is running first.. But if it's obviously underpowered and not trying to pick up the load,, (they act like they don't have a governor and they should act just like your lawn mower engine) then I'd look into making the adjustment...

 

[wheeler01]

Gotcha. Will give it a try. Ive got a tilling/grading job lined up this week with it, so Im trying to get everything up to snuff on it. Want to make sure itll handle what I throw at it. Thanks!

 

[DrBill]

Good deal... When you can, just let us know how everything went..