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Cat 920 Wheel loader

bam1968

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I have an issues with a Cat 920 S/N 62K12538. It has a 3304 engine in it. It has a manual fuel shut off that has (for lack of better words) lost the detent in the foot feed. So basically when I take my foot off of the accelerater peddle the engine dies. Initially I thought the detent was incorporated in the throttle linkage though I can't see anything in the linkage that would indicate that. So, I'm assuming if it's not in the linkage it must be a function of the injection pump. If so, is this something pretty simple and easily accessible? Digging deep into an injection pump is over my "pay grade" so to speak. Thanks in advance.
 

kshansen

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Guess it depends on your skill set.

I have had similar problem with 3306 engines that use basically the same governor arrangement.

Been a few years since I have been inside one but seems it was pretty basic stuff. The Detentes are just inside the cover the linkage connect to the governor shaft. In the picture below the shaft is marked with Green and the four bolts holding the cover on are Red.

I think the main thing is to make marks or notes of how the linkage arm is positioned on the shaft it the "off" position. When you remove the four, I believe 1/4 or 5//16 bolts note there is a spring under the cover. Not something that will take your head off but it is what holds pressure on things inside that gives the detente feature.

I don't think the shaft will come out but just to be safe hold in on it while removing the cover the four bolts go through. Once the cover is off you will probably understand how it works and also why it doesn't right now! Spring holds pressure on a couple plates that are also connected to internal linkage. My experience is two things happen. First where the pin between the two plates works it will cause wear on the plates making the detente less firm over time. Second water gets in past the seal and things get a bit rusty and sticky. Sometimes a good flushing out wit WD-40 or some such will get things working again.

Cat is not nice about showing the parts of the detente but the second picture below shows a view from the back with the shaft green and the same bolts red. Note the item #7 there a two of those and they are what the spring holds tension on to work the detente not shown or clear is that there are some pins between them that also are part of the detente system.

I know this is not the best description but like I said it's been a few years maybe someone else can do a better job of walking you through it.

920 gov01.png 920 gov02.png

One other thing is part #10 and part #13 are seals and gaskets and a good idea to replace but in a pinch you can reuse them as this area of the governor is not touched by fuel and you could just stick it back together to get going and replace them sometime later.
 

bam1968

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Ok Good. That is what I was hoping for (something fairly simple). For about a month I have been putting a little piece of wood under the pedal so the engine stays running when I take my foot off. So it's not a real big deal. It's just kind of aggrevating. Thanks for the reply.
 

crane operator

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For about a month I have been putting a little piece of wood under the pedal so the engine stays running when I take my foot off

With repair skills like that, you would fit right in with my operation. Actually this is a great example of how equipment has become way too complicated, and not easy to repair.

If this was a 2007 loader, you could have a bad electronic pedal, wiring issue to ecm, ecm bad, any one of a number of sensors or wiring issues. And you wouldn't have been able to run the loader.

Instead you've been getting by with a board under the pedal, and will be able to maybe stare at it long enough, to figure out what does what, from a drawing, and fix it.

Instead of having to call the cat man, pay him a hour drive time to your yard. Stand around while his computer "boots up". Listen to him bit#% about how the computer is so slow while he's on your clock. Then it will be some problem that has never been seen before, and he'll have to call the engineers at the factory. They'll put him on hold, or he'll have to email them, and then come back when he knows what the updated reboot magic solution is.

I'm not laying that fault on the mechanics, most of the ones I've been around are good at their work, its just the **** poor engineering that goes into this stuff, making things from plastic and tiny wiring, that won't stand up to 20 years of abuse.
 

bam1968

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Ok, so I took the cover (#9) off and couldn't believe the amount of rusty crud in there!! I cleaned it up and soaked it with penetrating oil and put the cover back on. It didin't seem to make any difference. So, back off with the cover. This time I took the bottom screw and spring (#4) out and the outside plate (#7) off. Noticing that it still needed more cleaning.... I then Pulled on the shaft (green). This is where I might have screwed up.... It sounded like a couple of things dropped further inside the governor when I pulled the throttle shaft. I'm assuming I now need to pull the entire governor to get things lined back up to put the shaft back in. My question is..... Do I have to get everything timed and pump pinned to pull the governor for any reason or is that not an issue as long as I don't go any deeper?
 

kshansen

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This is why I said to hold hold in on the shaft! I really don't know what to tell you now as the #1 part and maybe others have fallen into the governor housing. I believe, at least on some engines, it is possible to remove and reinstall the governor assembly with out removing the complete pump assembly form the engine. I did that job once maybe 15 years ago and I had a Cat pump tech go through the steps with me.

It is not something I would feel comfortable trying to explain over the internet! If you make a mistake and don't get the forks,#1 in the right position or the flyweights come out of position and you try to start engine there is a good chance of engine over-speeding and no way to shut it down!

Sorry to say but it sounds like you need to find someone local who has worked on these pumps. Best bet would be to find a retired Cat mechanic.
 

bam1968

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Earlier this evening I went and borrowed a service manual from a local contractor friend of mine. It looks pretty straight forward but I'm going to make a call in the morning to make sure before I go any further. Thanks for the reply.
 

kshansen

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Earlier this evening I went and borrowed a service manual from a local contractor friend of mine. It looks pretty straight forward but I'm going to make a call in the morning to make sure before I go any further. Thanks for the reply.
If this "friend" has the manual any chance he has a mechanic who has worked on these before? I'm pretty sure it can be done but it has been a few years.

I'm thinking the time I did the job I was replacing the two plates #7 in the second picture. As I recall there is a slot or hole in them that a detente pin latches in to keep it from going all the way to no-fuel. I recall that due to the rust and crap in there the plate was worn so the detente would not hold it's position, like yours is doing.
 

bam1968

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The two plates (#7) have grooves worn in them at the no-fuel position. But the detente pin also looks like it has some wear to it as well. I'm thinking the combination of the plate and pin wear is my problem.
 

kshansen

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The two plates (#7) have grooves worn in them at the no-fuel position. But the detente pin also looks like it has some wear to it as well. I'm thinking the combination of the plate and pin wear is my problem.

Not to sound too negative but that "WAS" your problem! Now the problem is getting in far enough to put those parts that went "clickity clunk" back where they belong and to do it so that engine does not over-speed on start up.

While it is not rocket science getting it apart and back together one has to be very careful and really understand how things work. If you are going to attempt this I would make the area around the governor as spotlessly clean as possible. It would also be a good idea to take lots of pictures and post some of them here.

Also might be a good idea to have a clean old bed sheet under the pump to catch any thing that might fall out.
 

bam1968

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Just an update of what I ended up doing...... I carefully pulled the governor off the back of the injection pump and was able to put the 'clickity clunk ' parts back where the needed to be (with help from the pics in the service manual). As far as my original problem.... I switched the two plates (#7) inside plate is now the outside plate and vice versa. Now everything seems to work as it should. Thanks for the help....
 

kshansen

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Just an update of what I ended up doing...... I carefully pulled the governor off the back of the injection pump and was able to put the 'clickity clunk ' parts back where the needed to be (with help from the pics in the service manual). As far as my original problem.... I switched the two plates (#7) inside plate is now the outside plate and vice versa. Now everything seems to work as it should. Thanks for the help....

So You are saying you have it back together and it's running?

I remember swapping the inner and outer plates on at least one of those governors myself, just could not remember with enough detail to try to explain it via text. Sometime you really have to be there.
 

bam1968

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Yes its up and running. Trust me I had a board ready to slap over the intake when I first started it just in case it decided to 'run away'. Thanks again for your help Ken.
 

kshansen

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Yes its up and running. Trust me I had a board ready to slap over the intake when I first started it just in case it decided to 'run away'. Thanks again for your help Ken.
Glad to hear of a success! There is another thread here that has gone the opposite way.
 
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