Hello,

I'm troubleshooting my low fuel pressure / hard start issue on my 1942 D2 5J. I have low pressure while running the pony and it kicks up to mid/high caution when main is running. It's not starting easy, i usually have to give the big motor a small shot of ether and just as it fires I kick the pony clutch out and then it keeps running. I checked the pony and it's running a shade under 3300 RPMS. Should I set it to 3000 or is 3300 close enough?

When I remove the small bleeder from the side of the filter housing I'm getting so-so flow, it doesn't shoot out.

I'm working from the fuel tank forward. I've disconnected the fuel line, blew compressed air back in to the tank and checked gravity flow and that is good.

Next is the transfer pump. I have pulled the line adapter block from the bottom. Everything came apart easy and the spring and plunger look fine but there is no spring stop, if that is missing will that affect my fuel pressure? I don't have a parts manual that covers this engine yet so what I know is what I've been searching for on this forum. I've found info of others not having this also and when it was installed it did not increase fuel pressure.

My transfer pump spring is 3.25" long. I've read others stretch it to increase pressure. This spring looks in great shape, should I stretch it to be longer to see if that helps?




I've replaced one of the fuel filters as that is all I had on hand, will replace the other two soon also to eliminate that. Putting the 1 new in didn't make a difference.

Thanks,
Jordan

I found a thread that mentions the pony should be 3000 RPMS so I'll try that. In that same thread it mentioned that it is typical to have very low pressure with just the pony running and that some times just the gravity pressure from a full diesel tank is enough to start a D2.

Perhaps my starting issue is the pony running at too high of RPMS. I'll see if I can adjust the governor down some and see if that gets the main to start properly.

Here is the thread I referenced above;

www.acmoc.org/bb/showthread.php?19411-d2-starting-issues/page2

Once the machine is running it performs fine. I just spent 20 minutes running around and pushing some dirt in my field.

Thanks,
Jordan

The problem with your pony running 3300 is with it possibly breaking the crankshaft, especially if it overspeed even more when the diesel begins to push it.

Stretching the spring isn't going to change much of anything except go ahead and break it if it's corroded much. I would leave it alone. I think the spring seat just prevents asymmetric wear on the first coil of the spring where it rests in the adapter block. Not a big problem in my opinion.

Does the relief valve poppet have a nice soft lip on it? The newer ones on the 1960's age machines are a hard plastic but I thought the older style from the 40's and 50's had a rubber seal. Also need to check the surface where it touches is flat. Got into the 922b the other day and found the steel seat was pitted. That plus the hard plastic poppet equals lots of leakage. I resurfaced the steel seat plate and installed a new poppet, but just got up into the green with the diesel running. Still doing some investigation but the transfer pump was rusty inside too and i cleaned up the cover plate pretty well, but didn't have the patience to lap the body down to get the side clearance on the gears close to spec. Can still catch the edge of the pump body with a fingernail off the top of the gears, so that is some of my problem.

Hi Team,
from my yellow SRB (Servicemen's Reference Book) Specifications Section, the pony is rated at :-
10 hp @ 3,000 rpm Full Load Speed -- That is most likely to occur in reality when the pony is engaged to the main with full compression applied on a cold engine on a cold morning.

3,300 RPM would be the expected High Idle Speed--that is at No Load, free running--the difference is the Governor Droop.
These little engines are cold blooded and hard starters especially if the valve heads are pocketed into the head seats--lowers available compression markedly.
Cheers,
Eddie B.

Thank you very much for the info. The poppet is aluminum and it felt like the sealing washer on it was like hard plastic. To me, the poppet and the spring looked brand new so I assume it has been replaced at some point. If I take it back apart I'll inspect the surface that the poppet sits against, I don't recall it being pitted but I know I didn't inspect that closely.

What do you think about replacing that hard washer on the poppet with a soft o-ring?

I adjusted the pony governor and it's running at 3030 RPMS under load now. The weather was around 90 out and I let the main run under compression for about 5 minutes before trying to start and I still had to kick the clutch out to get it to take off, no ether though. I'll adjust the governor a touch more next go round. I should probably let the main warm up longer and see if that helps I was just a little nervous running the pony so long on such a hot day.

I'm sure the compression is down on the main, it has a reasonable amount of blow-by while running so that probably adds to harder starting.

While I had it running today and took it over next to my 1942 Chevrolet G506 for a "Class of 42" reunion, matching patina on them. Though someone shot the D2 with new Cat yellow, something I will likely change at some point;



Thanks,
Jordan

Oh I also noticed while changing the transmission oil tonight that the right side of the D2 has 3 rollers that have been replaced with a different style, do they look like they are from a newer 5U perhaps? They look pretty worn and that side is wearing on the pins so I might need to pull them to resurface. From what I've read the 5U roller seals (bellows?) are more expensive than the seals in the 5J.



The left appear all original though resurfaced at some point and are wearing fine at the moment.

Thanks,
Jordan

You wrote:

"The weather was around 90 out and I let the main run under compression for about 5 minutes before trying to start and I still had to kick the clutch out to get it to take off, no ether though."

This statement makes me think that you may have retarded fuel injection timing caused by worn fuel injection pump components/ drive gear train wear. Since it was so hot outside I think that would have offset the suspected low compression issue in regards to a timely start.

You might consider checking your lift setting on the injectors (spill timing) as a retarded timing seems to adversely affect the ability of the main to accelerate up in RPM when starting. The engines seem to be unwilling to pull themselves up in RPM away from the pony turning them over even though they have good heat and plenty of fuel (black/ thick gray smoke from firing but just won't rev up and away from the pony turning them over). My experience with this situation is that you have to disengage the pony from the main at just the right time to get the main to take off.

Thanks for that info! I'll do some research/troubleshooting to investigate that as a possible cause.

Thanks,
Jordan

Hi Jordan, you are right about the D2 bottom roller seal price, as I understand it the 3J/5J used a conventional style lip seal worth about $12 a piece while the 4U/5U used the bellow seal which if you were to buy from Cat would cost big money, I think around $70 a piece, there are aftermarket bellow seals out there and I was quoted around $29 a piece from FP Smith or one of those other Stateside suppliers recently but it still makes rebuilding rollers expensive when you add welding them up and possibly replacing the bronze bearings, far better to keep your eyes open for good used ones or ask in the Buy / Sell section.

FP Smith in San Francisco did use to sell complete rollers for around $200 but looks like they only have one or 2 in stock now, most their stock came to Australia a few years back, North West Tractor seem to have a couple, using D24U/5U part numbers 7F6398 (single flange) and 7F6399 (double flange).
Mike