Timing won't advance?

[bmiszuk]

Today I checked my timing with a Snap-On MT480. I'm plugged into the #3 glow plug hole (2nd from the front on the drivers side), on the low RPM range on the meter with 99.5 degrees of offset. At idle (around 750rpm) I'm seeing 4 degrees ATDC. At 1300-1400rpm after the needle stops moving, I still see 4 degrees ATDC.

Is it possible the pump is not advancing at all? Around town it runs okay. On the interstate I have trouble holding speed up hills. If I press it too hard and it downshifts, I'll get a huge cloud of black smoke... and I mean HUGE! It's quite embarassing. Otherwise it only smokes black if I hammer it around town and even then, not a whole lot.

Any ideas?

[bmiszuk]

Everybody must be on vacation this week! Little traffic around the 6.2 forum lately.

Does anyone know if it's possible that the IP stops advancing properly? Would the truck still run if it wasn't advancing?

[BobND]

Yes, and yes.

Advance piston problems are COMMON with the DB2 pump, as some genius put a steel piston in an aluminum bore, and then put the whole thing in the bottom of the pump, where any dirt, debris, and waer particles will settle into it, leading to sticking, wear, and scoring.

[bmiszuk]

Can I fix it myself or do I need to have the pump rebuilt?

[bmiszuk]

<bump>

Do I need to replace the IP? Any harm in not doing it right now?

[5.7L oldsdiesel]

The injection pump can be removed and the advance piston can be cleaned very easily then.It's something you can do yourself.