Hello folks. I'm reverse engineering the pump and governor on my Cat 951C. Engine number is 78P46777. Pump has 6N0275 among other numbers. I have manuals for 951 and engine, which covers the pump/gov, but pretty briefly. Troubleshooting hard to start (sometimes starts well). Half the time it won't run. I learned a new term - asphaltine. New injection nozzles, removed, cleaned and reinstalled the injectors, and problem still occurred. Got the governor off, and found it gummy with the asphaltine. My question is, is the governor housing expected to be bathed in fuel? I found no data on this issue. Likely I'm short some technical manual for the pump. Tomorrow I'll be cleaning up the governor housing and studying the chambers, seals, channels etc to see if I can figure it out. This one was full of fuel. And dirty. Reason I'm suspecting that this shouldn't be full of fuel is it seems the flyweights should not be in a bath. Oh, I have cleaned up the fuel system, lines and new filter.
Don't. If it starts well sometimes, then try priming it before you try to start it and see if that makes a difference. If it doesn't start better, then run some biodiesel or other snake oil through the system and run it longer. I would assume everything runs in diesel if there's not motor oil in it, but don't take my word for it, and don't try to fix it.
I have been running diesel cleaner through it, and I'm confident that the lines are clean through the filter, up to the governor. I've let it soak and run some more. Sometimes it starts and runs fine. Then it won't. Even primed just no go. Found speed control feeling sticky. Inside the pump and governor housing is/was a gooey mess. I've owned it since last fall. Ran ok at first, got progressively worse. That was the alsphaltine in the fuel. Pulled over a gallon of the sticky stuff out of the tank. PO said he kept the fuel fresh, but it seems unlikely. I'm a mechanic (rebuilt over 150 engines - mostly aircraft) among other things, and have no problems working on this stuff, just seems Cat leaves the theory out of their manuals. Thanks for your input.
If that is a sleeve metering injection pump and governor then yes they run filled with fuel and under pressure.
I was slightly mystified to find that the SysOp for the fuel system was not in the online version of the 951C engine manual. Are the attached of any assistance or do they contain more than the engine manual for your 951.? Taken from a) a different product line and b) a different machine but are still potentially relevant IMO.
You're overthinking it. You found the gunk, get rid of the old fuel, get rid of the old tank if you have to. Work it for a full day the way it's supposed to and see if it gets better. If you can't work it for at least a few hours, you'll fight this. I'd bypass the steel tank, use a 5 gallon plastic boat tank so you can keep the fuel fresh until you know it's running good, and have figured out a way to clean the old tank. I'm not saying you can't figure out the injection pump, or take it apart and clean it up by hand. I don't think that's needed, or the best way to go about it.
Thanks all for the feedback. I must say that I stumbled on to this site around the time I bought my cat. I have been soaking up all the info I can about this machine, and the accumulated knowledge on this site has been a godsend. I currently have six diesels in my stable, but haven't gotten into the fuel injection previously. Thanks Nige for the documents. It turns out that I did have some of the info. But I didn't notice it until I read the documents you provided. And Old Magnet, it is a sleeve metering system. It seems to be credible to me that a sticky governor could intermittently be my problem. I'll report how this all works out.
Aieknocker, I'm not an expert, but your suspicion that flyweights shouldn't be sloshing around in diesel is likely a good one. I've never seen a governor on anything that was submerged in oil or fuel. I've noticed the Cat boys get pretty cagey about giving out much info on their pumps. My D4D had some problems with what seemed either the injector pump or governor so I dealt with the governor and took the pump to a injector shop (NOT a Cat shop) They just test ran the pump and confirmed that it pumped to expected pressures and would meter properly. Didn't cost more than $100 for the testing. (been a few years; can't remember exactly the cost.) The governor was assembled wrong; I was able to fix that on my own with a couple of parts. Jon.
Delmer, I have done all of that. I worked it for a couple hours when I got it. The PO told me he had put a new fuel filter on it. I believe that my have been true, but I believe the asphaltine problem developed after he quit using it. Then, years later I start operating it and I believe asphaltine got sucked into the system. I removed the injectors and cleaned them up. They were coated with the sticky asphaltine. I never knew about asphaltine until this experience. Basically, tar insoluble in fuel. I'm using a product called Penray Total Diesel Fuel System Cleaner. With it, I cleaned out the injection pump housing. And cleaned up the injectors. Cleaned out tank. Put a high concentration of Penray and fuel in a can, and filled the fuel system using the primer. That sat for a day and then I pumped it out. Engine ran fine. Shut down and no go. I've got 30 lbs primary pressure. I'm convinced that the sleeve metering is sticking. I have the governor off, and it's pretty crummy with the asphaltine. And it feels sluggish. I do appreciate your concern, and I hope I'm not too overconfident.
Jon, Do you have sleeve or scroll metering? And if not submerged in the fuel, where does your governor get its lubrication? Do you have a shield over your flyweights? My sleeve metering system does, i.e., weights in a chamber.
My pump does not look like yours, so I think I may have scroll metering. The governor is covered, like yours, and I put a touch of grease on all the moving parts. Jon.
Here is what it looks like. This is not rust. Penray wipes it right away.
That is a sleeve metering unit, sensitive to bad fuel, water, rust and deposits, anything that would cause sticking. Flyweights are enclosed behind that dome shaped cover. There should be a working back pressure bleed return flow to the fuel tank to help with circulation and venting of any air.
THAT gov. rides in FUEL.. Is there a flat plate thats bolted down across the top of the pump??
With a governor that looks like that I'm amazed you ever had it running! And I'd be a little nervous about starting it, if it can stick in the no fuel position and not run it can stick in the full fuel position and run away in a matter of a few seconds! How many years did this poor machine sit since it was last used on a regular basis? I'm thinking you need to start at the filler cap on the tank and clean everything nice and shiny from that point to the engine and back again to the tank.
Here is the set up. This was when I cleaned up the injector chamber. As far as I can tell, there is no return line nor bleed on this installation. I've concluded that with 30 lbs pressure in the injection chamber, plungers and sleeves clean and fitted nicely, lines purged to the nozzles, timing proven correct, and adequate compression that it must run. And sometimes it does. The only intermittent possibility has to be the sleeve position (governor). And as I dig deeper, I'm finding the gook (asphaltine) is worse than I thought. Looks like it has been accumulating for a long time. May have been in there for years, and the sitting it did before I bought it allowed it to stiffen up. Any one else experience this asphaltine?
And just to make it clear on the chance someone did not find this in the files Nige posted here is a out take on the fuel system for a 951C with sleeve metering pump 6N0275:
The history of this machine as it was told to me by the PO is that it was used to move slag in a NW Indiana steel mill. It's a 1979 951C. Company named Gray Co. I believe had a contract to do that work. Cat is (was) painted grey, and name Gray still shows on the right arm. Subsequently, it was owned by two different owners, who used it for personal property work. I suspect it has sat for a long time. And probably had fuel from the 90s or older. I've cleaned up the the system. All I have left is the governor chamber. I did reseal the tilt cylinders, including the front pins. Pulled the pistons and left the cylinders in place.
Kshansen, I had concluded based on what I learned from this site, and my observations that it was bathed in fuel, but your post makes it official. Thanks.
Well hope this does not muddy the waters or gunk up the pump any more but I'm attaching a fie of the first 39 pages of a SystemsOp I found while digging around on the 951C and the 6N0275 numbers. Not that it shows a few different versions of the sleeve metering fuel systems and it does appear that some do and some don't have return lines to the tank. A Full serial number off the machine might lead to more information on how this particular machine was built.
One more thing that may be of some help. The pages out of the Operation manual that shows where to find S/N's Not the clearest images but might give a hint as to where to look!
Here are the numbers: Cat 951C-86J5055-3V3020 Engine 78P46777-7N1521
OK, no tank return line on that unit.
Don't forget to bleed the governor when you get around to it. Don't think they tell you in the manuals
You've probably figured it out by now but.. in the pic on the 1st page.. the rod that goes from top to bottom..in the upper part of the rod is a "bell connector".. that links the gov to the pump.. THATS a straight link to the pump control rack.. Move it up & down & check for freedom of movement.. THATS whats moving the metering sleeves up & down on the plungers.. IF THATS FREE u wont have any problems.. U may hafta take the cover off the pump to clean that area{plungers}..again..??
Here is the governor housing. Believe it or not, that is not rust.
OK then what is it? Got bugs in there building a nest?
That gook looked like bits of soft plastic. Biological I presume. But the asphaltine coating cleaned up easily with Penray Total Diesel Fuel System Cleaner and a small bristle brush. Flushed it all with mineral spirits. I found the specific problem with starting. In this photo, see the partially pulled out shaft with a somewhat L shaped fitting. When the fuel control lever is moved to shutdown, that shaft is mechanically rotated clockwise (as viewed). This then physically forces the sleeve control shaft to move the sleeves down on the injectors, spilling the fuel, stopping the engine. It is a mechanical connection, and the sleeves must be moved, or something will bend or break. When the fuel control is moved out of the off position, the pin that rotated the above mentioned shaft moves away, allowing a "torsion spring" on the sleeve control shaft to move the sleeves up, and allow fuel to be injected. This spring is fairly weak. That shaft was so stiff from the gunk that although the mechanism could move it to spill fuel, the spring would not consistently move it back. I didn't tear it apart, merely cleaned it up, including the bore of the shaft, and reassembled, with new gaskets. Starts easy, and restarts easy. Thanks to all of you for your input.
This before cleaning.
Turns out the pump and governor are full of fuel. Since there is no return to the tank, the governor has a channel returning the pressure from the pump housing to the supply bore in the housing, thus the governor part of the housing, while kept full of fuel, isn't under pressure. This allows for circulation of fuel through the governor.
See post #14..
Would you please indicate where that channel/passage is on one of your pictures. Thanks
Not sure if this guy is still around or has figured out the problem. His last post was Feb 10, 2020 !
OK, I wasn't watching the dates when this post got referenced.