SD22 injection pump timing - replaced worn out belt

[emptech]

Using the engine to drive a water pump on a water truck. Engine died, discovered all the teeth had finally worn off from the injector timing belt. The replacement has to be exactly 69 teeth, width 19mm, tooth pitch 9.525mm which all translates to 3/8" pitch, 3/4" wide. We found a new belt from Dayco,

Searching several manuals, they show two timing marks on the injector pump, A and B. They also show a photo of a timing mark on the injector belt cover. Also is shown is a timing mark on the drive pulley on the crank. We have no such mark on the cover but there is a round indentation like the photos show.

Taking the drive pulley apart, we found a mark, probably when aligned up with some other mark on the engine, might be TDC? There is no pointer or other timing mark on the engine where we might align the two.

The A and B, according to some manuals point to two IP advance timing marks, the A might be 15 degrees before top dead center and the B might be 20 degrees, 18 for California.

We have not found the factory timing procedure. Somewhere we read where one would count so many teeth on the belt from the A mark to the mark on the drive pulley, if so, how many teeth, if that's the method?

Another possibility, set the engine so #1 is on the compression stroke at TDC, then back the crank 18 degrees, open the injector line for #1, rotate the pump shaft until #1 squirts, then put the belt back on. I think this would get us in the ball park but may not be precise

I have not been able to locate the FSM which shows the FE section, so I'm asking for some advice on this. I've spent many hours searching and this forum seems to be the best source.

Thanks - Jim

[plenzen]

Are you sure you have an SD22 here?

SD 22,25,33's are all gear driven.

Do you perhaps have a CD or LD motor here ?

[emptech]

That's what I was told but I haven't actually looked at the engine for any identification. One thing for sure, the IP is belt driven. I just got the message they got the engine started today, but need to find what was done about the timing. I'll confirm the model number. I got brought into the job because the person working on it was unable to locate a belt, I did.

thanks for answering my post - Jim

[asavage]

With a belt-driven IP, and four-cylinder, look for LD20, LD20I, LD20II engines for guidance.

[emptech]

With a belt-driven IP, and four-cylinder, look for LD20, LD20I, LD20II engines for guidance.

The proper cog belt was obtained, had to be the exact number of teeth, was installed and the engine ran. I wasn't there when the belt was installed nor do I know how it was finally timed. All I can say is that the engine runs, don't know if and how the timing was optimized. I will still follow up on your suggestion as to what model it is. Sorry I can't provide a more intelligent answer as I wasn't the primary person working on the project. I can only suggest that the person who did install the belt, got it running purely from good luck, certainly not his knowledge of diesel IP timing.

I want to thank all of you for providing suggestions and recommendations.

Jim

[asavage]

The cogged belts don't stretch the way vee-belts do (actually, vee-belts change their effective length by wear on the sides of the belt allowing the belt to ride lower in the sheaves, thereby requiring a re-tensioning, but we call it "stretching"). So a straight replacement of the IP belt wouldn't affect the before-and-after timing much.

If the engine truly is an LD series engine (and not an SD series, which as pointed out has a gear drive for both types of IPs), the actual timing of the injection event is accomplished by loosening the three nuts that fasten the IP to the front housing, and rotating the IP -- very much like timing a distributor on an old-school gasoline engine.

However, the base timing of the Distributor style IPs (as used on the LD engines and many, many others) does not need to be checked or changed regularly; you only check it when you have to remove it for servicing, upon reinstall.

Sidebar: The Distributor style IP has an internal lift pump that pressurizes the internal housing of the IP as the RPM rises, and that rising pressure actuates an internal hydraulic timing advancing mechanism. As the IP ages, the lift pump cannot adequately build pressure, and therefore full injection advance never occurs. The result is black smoke from the relatively retarded timing. As the lift pump -- which is a vane pump -- wear further, it will eventually get to the point where it won't even pull fuel through the filter. Rebuilding the IP and replacing the lift pump's elements is the only effective solution. Installing an external lift pump to "push" fuel to the IP will allow it to run, but there will be no injection advance at all.

This is a very, very common scenario with the Distributor style IPs, both by Bosch and the design licensed versions by Kikki-Diesel and others.

The Inline style IPs, as used on (almost all) the SD series engines do not suffer this particular problem: their lift pump is a plunger style rather than vane style, and their injection advancing mechanism is a flyweight-and-spring arrangement that is external to the IP -- it is integral to the gear drive.