How I fixed a runaway L260 engine

[pejepscot]

I hate it when someone asks for help with a nagging problem and then doesn't let us know how it got resolved, so in the spirit of education, I offer this to my fellow L260 owners (and others!)

I thought I'd show how I (finally) fixed the sticking injector pump which caused my old L260 to "runaway" at near full throttle about a month ago.

The problem was a sticking fuel injector control rack which is part of the injector pump. This is the model injector pump used on my 1975 L260:



it is located right here in the RH side of the Z1300 engine:



The injector pump is integral with the governor (shown on the left side) and has a small inspection cover allowing access to the two pump plungers:



The governor and the pump each have their own oil sump and dipstick. the governor has a fill cap and a drain plug; the pump side appears to have neither (weird!?):



There is a sliding gear-toothed rack that slides side to side, turning the plunger adjusting pinions and adjusting the amount of fuel that is delivered with each stroke of the plunger. When the rack is all the way to the right, the plungers deliver maximum fuel (full throttle). My rack was sticking wide open on cold days and causing the motor to start and run at full throttle (very scary!) no amount of cleaning and lubricating in this area cured the problem:




Then I got an idea... notice the small cap or "can" on the left side of the pump casting. The rack extends out from the casting and into this "can" when at full throttle. Perhaps this "can" had moisture in it which froze on cold days and held the rack in WOT.



I went out one cold morning and opened the side cover. Sure enough, the rack was stuck in WOT position. I took a heat gun (i.e. a hair dryer) and applied heat to the "can" and in about 25 seconds the rack released and moved freely! EUREKA! it MUST be water in the can, but how to clean it out?

I stared at the can for a while and saw that it had two flats, so I put a 19mm wrench on it and gave it a tug - voila, she unscrewed and out dribbled about a teaspoon of water!



I thoroughly cleaned the end of the rack and dried and lubed it well:



I did the same with the can itself:




And now the problem is SOLVED. I have driven the tractor a few hours in cold rainy weather and started it in below freezing mornings and she seems to be fine!

I love the challenge of figuring out a problem and I am impressed with Kubota's engineering. To make this "can" easily removable is brilliant!

One question..should I fill the can with grease perhaps?

Anyhow I hopes this helps some other L260 owners!




Cheers,
Ren

 

[Daren Todd]

Great info and thread

 

[Dieselbob]

I REALLY liked the way you documented everything with the pictures. GREAT JOB!

 

[skeets]

Thats grand and I agree, ask a question at least post back and say what happen

 

[Tooljunkie]

Awesome How-To. Two thumbs up!

 

[sheepfarmer]

Thank you so much for the labeled pictures! Fabulous!

 

[Lil Foot]

Excellent diagnosis, description, & pics!

 

[CaveCreekRay]

Awesome!

What program do you use to make the arrows and labels? I have wanted to do that with some of mine.

More of that kind of quality write-up and the rest of us are gonna be out of business.

 

[Diydave]

drill and tap end of can for a grease zirk...

 

[D2Cat]

As easy as it is to remove the cap, I would only put a small amount of white lithium grease in and reinstall.

You put a grease fitting on the end you will eventually get too much in there and have the problem all over again.

 

[pejepscot]

Cavecreek, I used Adobe Photoshop, but there's got to be some free open-source software out there that will do it. I like the white lithium grease idea. I have some assembly lube I think I'll put in there, it is very non viscous.

 

[sheepfarmer]

Pejepscot, I also have Photoshop and have been wondering about image size and pixel resolution to make a picture to post here. Could you tell us how you got your images to post in the message so nicely? Are they in Photobucket or ? I saw the hints, but I am still not sure.

 

[pejepscot]

Sheepfarmer, once you have the image looking how you want I t in Photoshop, go to ADJUST and set IMAGE SIZE so the longest dimension is 850 pixels. Then I choose SAVE FOR WEB AND DEVICES and save it with a new name.
At this point I upload it to Photobucket. When writing the post here on OTT, I have Photobucket open in a second browser window and as I'm writing if I want to insert the picture I go to Photobucket, display the picture and to the right of the picture I click on the URL link, that automatically copies the URL code for the pic. I then return to what I am writing and paste the URL code where I want the picture to appear in the text.
Preview the post before submitting to be sure the pics ended up as you wanted.

 

[Apogee]

Excellent job both on the repair and documentation.

Thanks for taking the time to share with the rest of us.

Happy Holidays,

Steve

 

[wild bill]

Cavecreek, I used Adobe Photoshop, but there's got to be some free open-source software out there that will do it.

GIMP is a free open source clone of photoshop.
http://www.gimp.org/

 

[coachgeo]

.....
At this point I upload it to Photobucket. When writing the post here on OTT, I have Photobucket open in a second browser window and as I'm writing if I want to insert the picture I go to Photobucket, display the picture and to the right of the picture I click on the URL link, that automatically copies the URL code for the pic. I then return to what I am writing and paste the URL code where I want the picture to appear in the text.
Preview the post before submitting to be sure the pics ended up as you wanted.

NO NO NO NO NO....... unless what your posting will not be of value to any future reader a week, a year etc. down the road then always attach by uploading the picture to this site so it will get archived. If it is of a pic of no future value then why post it at all.... but that is a different topic.

Things change.. you might rearrange things in your photobucket account, Photobucket might change/upgrade servers orrrr?? Happens all the time and when it does the images put in as you describe go blank. These blanks make threads and post worthless to future readers. Blank pics show potential new members the board is obsolete and not worth joining. Old members find the board obsolete and not worth sticking around... Brain drain... board dies from lack of use

It is very easy to attach images on this site that will get permanent archival. This site is also a rare bird in that you can attach images from other sites like photobucket, another tractor site, a part vendors site, etc.

 

[coachgeo]

Awesome!

What program do you use to make the arrows and labels? I have wanted to do that with some of mine.

More of that kind of quality write-up and the rest of us are gonna be out of business.

there is free online pic conversion/resize sites. Nothing to download.

You don't need anything as big/complicated as photoshop. Way to complicated if all you want to do is add text and resize.

best easy FREE windows based image product is Paint.net Just enough features yet very simple and very easy to add more components; still at no cost, as you get more image manipulation savvy

 

[pejepscot]

Coachgeo, duly noted. I will strive to change....I'm an old dog and these new tricks sometimes pose challenges.

 

[RichardW]

I am looking at an L260. The owner says he replaced the head gasket, it requires a shot of ether to crank(maybe bad glow plugs?) and the engine tries to run wild and has to use the decompressor to shut it down.

It supposedly has less than 300 Hrs on it, sheet metal and tires look really good so hours maybe right.

So does anybody have any advice on what to look for as possible issues or should I just run!

 

[DanDan]

Excellent troubleshooting and repair; thanks for the detailed documentation.

You might change the thread title to "How I fixed L260 stuck in WOT" though; this does not sound like a true "runaway" where the crankcase oil gets drawn into the intake...