D8H

[peter82]

I have a D8H 46a31000 it runs fine idling but when throttled up engine sounds like it is surging up and down i put new spray nozzles in it and have changed fuel filters would like to fix this problem thanks
 

[Bob/Ont]

Peter. go to the front of the injection pump where it mounts to the drive housing.
Look for and take off the small oval cover where you measure the rack travel. With the engine running and surging, hold a short pencil or something like it against the end of the rack to stop it from pulsing in and out. Don't push the rack in, just stop it from pulsing outwards.
If the engine runs smooth, you need to replace the horseshoe spring and two dowels that connect the pump camshaft to the governer drive gear.
Later Bob
 

[jm.]

That is REAL CAT experience.. Explained well and I agree you are right on, Owned several of the old 46As.
 

[Mr. T. Minnesota]

Peter,
Had a 242 Ford diesel on a Tree Farmer that would surge at idle and seemed powerless when attempting to move. Got advice to remove a flat plate on the injector pump and carefully check the travel of the rack slide mechanism. Turned out to be varnished and sprayed carb cleaner on it and it ran fine after that.
Hope this helps!
Mr. T. Minnesota
 

[peter82]

i will take it off monday and see what happens
thanks i will post a follow up
 

[peter82]

I took the cover off and started dozer i could see the rack pin pulsating in and out and dozer would surge when it would go in and out how big of a job is this to fix how does this pump time? I have a parts engine that has a pump on it could i interchange the parts or would it be best to just order new thanks
 

[Bob/Ont]

Peter, if you want to get someone to do the work the pump is on an offset tang and doesn't require retiming when you remove and reinstall it. I would recommend going to the dealer and ask if one of their(OLDER)shop mechanics would do it for you. A fuel shop might want to do a complete rebuild. The drive spring will stop the surging. You could try using the whole pump from your parts engine. It's best to use new CAT parts, Talked to a guy with this problem on another engine that a fuel shop said they replaced the spring???? If you don't use the parts engine pump, practise on the parts pump first.Make sure you can always force the rack off when finished. Rack pulled back into pump from front. Come on back if this isn't clear.
Later Bob
 

[peter82]

does pump have to come off or can i just take the govenor housing off and put it in from there as long as i dont adjust the fuel bolts i have a cat service manual
 

[peter82]

you talk about rack going back into pump from front. the rack needs to go back into the pump towards govenor housing. i took the govenor housing off junk pump and i found the drive spring it looks good on the junk pump is there anything particular i need to check for on spring
 

[peter82]

any suggestions on removing dowell from cam
 

[Bob/Ont]

Peter I think you are doing okay with it.
Just make sure the gear is firmly attached to the cam.
I may have missed this pete but take a torch and heat the dowel in the cam red hot, let it cool and then it should pull out of the cam easily. If not reheat it and cool quickly with cold water, that will shrink it.
I think you should email me with your phone#
RBPlasma@gmail.com
Later Bob