RD4 main engine starting problem

[R4pat]

my brothers and I have a RD4 that we have a hard time starting, when we bought it the engine was stuck, since then we have put new sleeves, and piston rings in, had the head rebuilt with all new valves in, had all the injectors lapped, and set to pop at 1500, our pony cranks it over really good, has lot of compresion, the main engine tries but never takes off and runs unless we give it a little starting fluid, after its running, it does't really run real smooth, but pretty good, i'm not really satisfied, we have pulled a plow with it probably 20hrs getting it good and warm getting everthing seated, I think it main engine should bust right off as soon as the pony egine is engaged, but it doesn't, could it possibly be the injection pumps, and is there a simple way of setting them

Thanks Pat

[SJ]

There isn,t any setting for the inj. pumps themselves but you could take them to a Cat dealer or fuel injection shop to have them checked out but what you can do is check the lifter screws that lifts the pump plungers & they have a setting with the flywheel marks on their particular cyl. There is two different camshafts in those engine but the setting is only a couple thousands apart so with the engine on TDC of the cyl.you want to set the lifter screw will just start to move up from it,s bottom position & with depth mikes set them at 1.733" which is .001" higher than specs but it will make up for wear.Turn the crank to the next cyl. & so on till you set all of them. Firing order is 1-3-4-2. This might help your starting problem if the lifters are low in specs.

[ccjersey]

SJ,

While running a leakdown test on our D69U, I found that the flywheel marks apparently are not TDC marks, because the engine always turns when you put air pressure a cylinder when it's set on the mark. They must be special injection timing marks that are advanced ahead of TDC to get the proper injection advance.

Anyway, he should use the marks on the flywheel to time each lifter, not be looking for TDC. Also always turn the engine in the normal direction of rotation up to the mark, if you have to back up, back up a lot and turn back up to the mark again so you don't have any slack in the gears that affects the timing.

As you say, the lifter to set will just be starting it's stroke when the mark comes up to the pointer. If it isn't moving, then the other cylinder listed at that mark should be the one to set. For example 1-4 on one mark and a half turn later should be 2-3.

Another thing to check is the loaded rpm of the pony motor. I believe EDB posted the rpms of the diesel, but the pony motor is rated at 3000 rpm under load, so if it isn't turning that fast, it may be holding the diesel back. The 212 grader we have is like that, you have to disengage the pinion clutch to allow the diesel to take off on it's own. Then it kicks out the pinion latches like normal and runs great.

[R4pat]

wouldn't you think it should start right up without starting fluid, we've adjusted the lifters enough to get it running, but maybe they are still a little out of adjustment, and as far as I know, Cat does'nt have parts avaible for the pumps,

our pinion also won't always stay in, but like you said, i have tried letting off of the clutch to lett it take off, but still it won't quite take off,

[Old Magnet]

The D4 pony is rated at 10 hp@3000 rpm (D6 is 15hp)
The governed high idle speed is 3350 rpm.
The pinion release rpm (factory set) is 3515 rpm.

You are not free from drag until the latches release.

[ccjersey]

Nothing says the pinion latches are tight enough for 3000 rpm. That would be the place to start in my opinion. Check the pony rpm turning the main engine under compression, throttle closed on diesel. Set it to 3000 by tightening or loosening the governor spring and get the latches adjusted to stay in at that speed. Each turn on the latch spring adjustment screws is worth around 100-150 rpm. You have to adjust both springs equally each time you adjust.

On the pumps and injectors, you can take the lines off the pumps and take the injectors out and then reinstall the lines turned out over the track with the injectors pointing down (or just remove the injectors and turn them upside down on the lines so they are over the PC chambers, just pointing up)

then start the pony motor, engage the pinion, open the diesel throttle and use the clutch to start and stop the diesel as needed to observe the spray pattern. If you see one that's not doing well, you can swap it with another one that is doing well and see if the bad spray follows the injector or stays with the pump.

You want a fine, even spray with no drips or stream of diesel. Sometimes an uneven spray pattern can be fixed by using the correct sized drill and cleaning the carbon out of the nozzle bore. I expect someone here can tell you what is the correct size if you need it and you can find a drill somewhere to use in a hand chuck, not a motorized drill.

BE CAREFUL, the fuel will go right through your skin if you get too close to the spray. If you get fuel injected, it is a real emergency, get competent medical care immediately.

[gauntjoh]

At risk of asking the obvious, how long are you cranking the diesel against compression before you open the rack to start the diesel ?
With my own, and my brother-in-law's D4s (one 7j, one 2T), we need to crank against compression for 5 minutes at least, until the (diesel) cylinder head is almost too hot to touch, before opening the rack to start the diesel.
If you try before this, it just won't fire, (but would probably do so if you sprayed ether in the intake).

[SJ]

CC those marks on the flywheel for each cylinder is TDC for the pistons but say it,s on 1-4 mark then # 1 will be TDC firing stroke & the # 4 TDC will have cleared the firing stroke or vice versa, which ever one your on for the firing stroke. Always make sure the flywheel is on the correct position & the marks then will be right in relation to the piston.

[R4pat]

I have not been using ether, just a starting fluid with a small percentage of ether made for gas and diesel engines, I know my injectors are all working right, I going to try checking the rpms on the pony motor, and if thats not it, i'll try adjusting the lifters, we had heck getting running after we first got it all together, and we did some adjusting on them, because they were way off for some reason, i do know the some of the lifters are worn pretty good, but i can't find any new

[catskinner]

You have to let the pony motor turn the diesel engine over for a time in order to warm the diesel engine up for it to fire. You can't just engage the diesel engine and open the throttle and expect it to start right up like that. Once it has been run that day, and is warm, it will start like you are trying. catskinner