D4600 Flywheel Positioning

You're right on the 120* out. No problem, lots better to be 120 out than 60, at least you have a mark to line up. Adjust the valves on the cylinder of each pair (1-6, 2-5, 3-4) that has NOT just had the exhaust close and the intake opening as you went to the mark.

Set injection pump lifter when you reach the mark (which is TDC). Do not back up to get right on the mark, only go normal rotation and stop on it, if you go past, go back a long way and come up on the mark again so you take out any wear/slack in the gears when you set the lifter. Make sure to set the lifter that has just risen or you will break things as you rotate it around to get the others done.

Timing dimension for D318 is 1.736, not sure about the D4600. there should be a flat on the top of the lifter yoke that the pump plunger engages. Measure from top of pump housing to this lifter yoke flat top. D318 book says that lifter should still be rising after TDC, not falling before TDC as you indicate. Are you sure you are rotating the engine the correct direction (clockwise standing in front of the tractor looking at the radiator). You may also have a mistimed pump drive gear or perhaps a worn lobe on the pump camshaft if they all don't show that same drop.

The 1.734 in. measurement is correct for the D4600.....measured from the top of the injection pump housing to the bottom of the yoke.

This measurement gives you the proper built in advanced injection point.

Cat finally wised up starting with the the D330 & D333 and other later engines at that time by positioning one of the flywheel bolt holes off center so you couldn,t get it on wrong.When setting the lifters they will just be starting up from the bottom position when your on the timing mark to set it. bboaz in your case your not on the correct marks but if it,s as you say with another set of marks the process is the same as all have suggested.

I finally gave up and pulled the engine back out of the frame. Pulled the heads, pan, and front timing gear cover. The flywheel is in the correct position. When 1&6 line up with the timing mark 1&6 are top dead center. In one position with 1&6 lined up the timing marks “C” on the crankshaft, and “C” on the cam gear are together as the picture shows in the book. Turn the flywheel one revolution and line 1&6 up again and the “C” on the crankshaft is back in the same place as before yet the “C” on the cam gear is 180 degrees opposite. Am I correct in saying when the “C’s” are together number one cylinder is firing and when they are apart number 6 is firing? With the “C” together as in the picture and the “C” and the “P” lined up on the accessory gear and the idler gear this motor should be in time. Should number 1 Fuel Injector Pump Lifter be coming up when the “C’s” and “P’s” on the idler gear and accessory drive gear get lined up or at this point shouldn’t the lifter be just about at the end of it’s upward stroke and starting to go back down? I still have to adjust the Fuel Injector Pump Lifters because they were adjusted thinking the flywheel was 120 Degrees out of position. Once adjusted as each timing mark comes up on the flywheel, the corresponding Fuel Injector Pump Lifter should be coming up. At what point in the upward travel of the piston on compression stroke should the Fuel Injector Pump Lifters start their upward stroke? What I am seeing now is the piston strokes and the Fuel Injector Pump Lifters are not matching up. The timing marks are lined up yet as number one cylinder is top dead center and the flywheel marks are lined up it looks like number 5 Fuel Injector Pump Lifter is at the top of it’s travel. Is there that much advance in the Fuel Injector Pump Lifters? Am I reading too far into this situation? I have put too much money and time into this engine for it not to run

WOW,
Sorry to hear you are having so much trouble.
Yes, when all the timing marks are aligned you are set to power stroke #1 cylinder which should be at top dead center. The lifter should start to rise on compression stroke and be at the 1.734 in. position at the top dead center mark. A check of the correct position is the lifter still rising as you turn a few degrees past the TDC mark.

Remember that the injections pumps are numbered 1 to 6 consecutively starting from the front but the actual firing order is 1-5-3-6-2-4

The camshaft turns at 1/2 crankshaft speed so your 180 degree would be normal.

Advance on the injection pump stroke would only be around 15 degrees. (D318 is 15) This would be around 3 inches travel on the outside of the flywheel rim ahead of the TDC marks.

I gave away my D4600 book, so I can't tell, but do you have a complete set of 4 marks between the accessory shaft gear, the idler gear and the cam gear which align all at one time?

The D318 book shows a one piece double gear on the cam with the accessory drive idler running on a smaller outer gear that does not mesh with the crankshaft gear. Also shows that the idler gear marks are not straight across from each other so that they would both align with the cam and accessory drive gears only at the 1-6 piston TDC.

No problems with these and no substitutions of gears etc, then the only possibilities are a sheared key or twisted accessory drive shaft.

Do you have any history on this tractor before you tore it down? Looks like there would be some evidence of prior attempts at repair or history of failure.

Or was it "running when parked"😄

Thanks OM and CCJERSEY for your comments. I have readjusted the Fuel Injector Pump Lifters Where I had thought things were 120 degrees off. As the piston for the firing cylinder approaches top dead Center and the timing marks on the flywheel line up the Fuel Injector Pump Lifter for that cylinder starts up. Here I set the 1.734 with a depth micrometer. As I turn the flywheel to the next mark (i.e. set number 1 turn to the next mark to set 5 in normal firing order) the Fuel Injector Pump Lifter for number 1 cylinder continues to rise through the power stroke of that cylinder. Is this correct. It seems the cylinder is firing late. The way this is set it makes the majority of the fuel injection process take place during the downward stroke of the piston in the power stroke. Maybe I expected to see more of an advance (BTDC). Does this sound right for the Fuel Injector Pump Lifter travel in relationship to the piston travel?

I measured one of the Fuel Injector Pump Lifters prior to readjusting and the measurement was 1.906. This would be .172 low. Would this make the fuel injection for that cylinder even later? If so could this be an explanation why there was lots of white smoke and would only fire once and a while.

Not much history on this tractor other than it set for about 20 years collecting water in the cylinders. There was lots of rust and corrosion to clean up. Don’t know if it ran when it was parked or if that was the reason it was parked.

If this all sounds correct, maybe it is time to put everything back together and see if it will run.

Thanks for your help.

Hi bboaz,
Yes, if your lifter setting is 1.906 your timing is way late.

Yes, the lifter should continue to rise from the 1.734 in. setting.

According to my fuel injection handbook for the D4600 the timing is 25 degrees before top dead center. (15 degrees on the D31😎

I'm including a picture of where lifter measurement should be taken as there seems to be some confusion and I just received a couple of PM's asking for clarification.

Did you actually pull an injector and verify TDC indexing, preferably with a probe and dial indicator??