Hey folks, Got a D6C that's been setting for probably 10 years. It will start and idle but won't speed up. I'm guessing the fuel rack is stuck but not sure. How can I be sure? I know there is a cover plate that can be removed to install the rack setting gauge. If I remove that, how much should the rack actually move? Any help would be greatly appreciated!
https://talk.newagtalk.com/forums/thread-view.asp?tid=485006&DisplayType=nested&setCookie=1 Does your pump look sorta like this one? That thread should help if it does. The rack should move enough that the individual injector pistons rotate most of the range of the gear teeth. I'm not the pumpguy, but if it's running on all cylinders then the plungers aren't stuck, so I'm not sure what else would stick on the rack? Have you already changed the fuel filter and blown out the lines before you take the cover off the pump?
Rack movement is 0.312" from 4th tooth of the gear segment in either direction. (5/8" total)
As always a full S/N and even better a picture or two of the injection pump will let people know what the style of pump you have and that will have strong bearing on what things may be causing the problem. Just had an idea. Do you have good oil pressure? Depending on the pump style many older Cat pump had a simple device that would hold the pump in idle position till oil pressure got to the right amount. I would try hooking a known good remote gauge to the engine and see what real pressure you have. It should only take a few seconds to jump up to 60 psi or more at idle. If you do not have good pressure in a few seconds I would shut down the engine and figure that out before running any more.
KMashburn , Just so you don't think I'm ignoring you I will be away from computer access after Tuesday morning for a few days. I'm sure others here will be able to help you if you come back with some more info or pictures.
D6c's 76Axxxx all use the compact fuel injection pumps.
Sorry for the delayed response, been away from computer for a few hours. Serial number in 76A 1543
Thanks Old Magnet! Ser. no. is 76A 1543
Thanks for the reply Delmer. My pump is a scroll pump I believe, no access cover. Filters have been changed, and line cleaned out.
Thanks kshansen, oil pressure is unknown, will get a good gauge and check.
Old Magnet will the rack move the 5/8" with the engine off. Does the oil pressure detent keep the rack from moving until oil pressure is built up? Thanks
Ken here not Old Magnet, But as I recall the lever on the scroll pumps will only move enough to get the pump out of the shut down detent position until oil presure moves the pin out of the way. Actually was thinking that if pressure from governor control linkage was putting pressure on the detent spring it could be not letting it pull back out of the way. Once you are sure you have good oil pressure I would start by disconnecting the linkage right at the pump and start engine and see if you can get engine to rev-up by moing lever by hand. I'm attaching the file with some information on the scroll pump governor. Below I also took a screen capture out of it and colored the plunger red that hold the governor from going past idle till oil pressure comes up. If it's not clear from the picture this plunger is under a cap on the block side of the governor, something like a 1 inch wrench to remove. On an engine that has sat for many years there could be some rust or other problem not letting this plunger move free. Good luck, like I said I will be away for a few days so hopefully you will have it figured out before I get back.
The speed limiter controls the governor, the rack can be set or moved without the engine running. The compact fuel injection pump is a scroll type pump but they were not referred to as a scroll pump at the time.
Hi Ken, Kenneth here. Thanks for that info. Will get a closer look at it this weekend.
Thanks Old Magnet. Are you saying I should be able to move the rack full travel with engine off? It would be great to know if the rack is not frozen, if not, I'll take a closer look at oil pressure, and the oil pressure detent assembly. The last time this Cat ran, it fired up ok, I revved her up a couple of times, then for some reason, it would not go above idle. Thanks
Update: Yesterday I removed the speed limiter cover, noticed the governor collar and bolt were free to move about a 1/2". I removed the fuel filter and transfer pump assembly, as well as the small cover where you install the rack setting gauge. With the speed limiter removed I was able to see if the rack would move it's full travel. No luck, rack did not move at all. I used a small socket on an extension and with a small hammer gently tapped on the end of the rack. After 10 to 20 taps it freed up. Now moves the full range of movement.
Figure out what hung up, fix that before you have it stick the other way, WOT.
If you decide to get brave and start it now I would strongly suggest you remove what ever you have to from intake side of engine to be able to use a plate of 1/4 inch or thicker steel to block off the intake if it does start to run away. Also make sure you don't get a finger caught between the steel plate and the intake of the engine. Safest thing might be to remove the individual injection pumps and inspect them very close for any corrosion. Then next thing might be to remove the rack itself to be sure that also is clean and free of corrosion. But it you are going that far might just be better to take complete pump to a pump shop to be gone through. Not sure if thepumpguysc works on Cat pumps but might be worth checking with him. He's only one state away from you. Just better to spend a few dollars now to save destroying a complete engine if it does run away!
Thanks Ken, I have the Cat tool to remove the individual pumps, but no other tooling. Not confident I can pull them out, inspect, clean, and re-install and keep everything in proper order.
Thanks DMiller, last thing I want is a runaway engine!