jdemaris- got a question

This M1008 truck I bought has a little glitch in the injector pump I think..After start-up , I drive the truck down the street and it will "cackle" loudly for about 3 to 4 seconds after 1st to second shift..Only does this after cold start-up..My thoughts are the advance is sticking from 23 years of sitting around not being used..I got a bottle of Stanadyne fuel additive/lubricant..Gonna try that.. Any thoughts ?? Thanks , Roy

Those 6.2s are known for the fuel advances being the first thing to wear out or get weak on the DB2 pump. With military rigs, they wear even faster because of the JP8 military fuel. So, if anything, I'd suspect the advance of being worn and not moving enough. I doubt it's sticking, more apt to have low fuel pressure or leakage.

Funny thing is - when those pumps are used on most farm tractors (IH, Deere, Ford, AC, Oliver, etc.) they have a steel cylinder with a piston riding inside with a sealing ring. But . . . on the 6.2s, they use a piston riding directly in the soft aluminum bore of the injection pump housing. The setup tends to wear.

A very general rule-of-thumb is this. When you first start it cold, and rev the engine up in neutral (i.e. no load), does it rev smootly, or does it break up? If it breaks up no-load, but tends to smoooth out when you actually drive it, the advance is probably too retarded.

Easiest work-around is just unbolt the pump and physically move it 1/16th or 1/8th of an inch to advance. Yes, this will also change the static timing, but it usually does not hurt a thing. In fact, it will often improve cold starting.

There were many service bulletins for your engine posted by the US Army and the wear problems associated with the thin JP8 fuel.

If you really want to know for sure, and don't like guess work - you're going to have to get your hands on a timing light. Either powered by a Piezo microphone that hooks to an injector line, or the more pricey luminosity probe that screws into a glow-plug hole.

Starts easily and revs good , no stumble or miss..Do you think it would be worn/leaking at 2400 miles???? That's why I thought it might have been sticking...I have to believe the mileage is correct due to condition of truck..Interior floors painted olive drab with nearly no wear marks in the paint , and a bed floor that isn't even scratched....