I know that clatter at start up is normal. And cold engine clatter is normal. But, I noticed that I still have quite a bit of clatter even under a load with a warm engine. I've had my truck running next to other IDI's and mine is always the noisy one. should I mess with timing? The truck runs great! no smoke, good mileage and all that. What do you think?
Thanks, Justin

 

i wouldn't worry about it if it's running good ..

might be you are hearing wrist pin noise ..

sometimes mine is extra clanky and i used to get concerned but after years and years .. i just realized it's just a clanky mechanical diesel ..

i do also add just 1/10 of a bottle of stp oil treatment to quiet it down a little on startup .. at least i think it make an improvement .. these motors seem meant to be run warmed up .. when i start mine it's clanky and i can hear the internals gradually expanding .. ie pistons .. rings .. bearings .. that big motor seem loose to start and expands to run perfect when she's warmed up ..

 

I always adjust mine - chances are that if you play with it and get it 'perfect', you'll have better power(less fighting itself) and fuel economy(same reason).

I just tweak it to where it has a very slight clatter at highway speeds in high gear, which stays the same when I floor it under load. If you have a turbo, you can then retard it a little more. NA engines like it slightly more advanced.

Remember, if it /feels/ more responsive and powerful, it probably is.

And, at this point, your IP and injectors are probably nowhere near the 'factory' timing due to wear.

 

What is your timing currently set at?

Mine is about 9* and it's very loud when old cold advance. When that comes off it's a little noisy at idle but not very noticeable at higher RPM. When I got the truck it was at 6.5* and sounded like a SBC. I've wondered if it's too much timing and could be detrimental long term but I disregard that and figure if it's in the generally acceptable range of 6.5*-10* there's no harm. I've read some have run more than 10* and reporting improved performance but it kills glow plugs.

 

Going to show my ignorance here but what does timing have to do with the life span of glow plug?

 

Not sure myself. I've always found electrical issues to be the cause of fried glow plugs.

I mean, if the thought is higher combustion temps, well, what about a turbo motor with boost? That will definitely create some serious combustion temps even at 'retarded' timing.

As far as what degrees, I gave up on using my timing light about 3 trucks ago. I've got it, but I just do it by ear and feel now.
Because even if my light told me "6 degrees" or "8 degrees", but it sounds off to me? I'm going to fix it.

As it is, I'm pretty happy with the performance of my trucks with these timing adjustments -- lots of power, no smoke except black at WOT, relatively quiet and not sounding like it's about to throw a rod.

 

I'm not even sure what my timing is set at. Its been a good runner since I bought it that I haven't even checked. I'm getting the feeling its about due for adjustment. Just got 150k on it now.

 

I'm not sure exactly why more timing kills glow plugs but I've read that from a couple people who have experimented. Maybe higher pressures when it lights off or more turbulence or shock to the plug.

More timing advance should generally result in improved power and economy so long as the flame front doesn't start exerting significant force on the piston before it passes TDC. What is ideal depends on combustion chamber design just like a gas engine. Inefficient heads need more timing, efficient heads less. Not sure how precombustion chambers and early vs late precups put the IDI heads. I haven't done any experimenting with different static timing or curves, I just know my truck went from 8.25 MPG at 6.5* to 10.5 MPG at 9* with no other changes. Macrobb has mentioned slightly less timing at full advance is best for max power and the light load advance cam can be adjusted to keep more advance at lower RPM/accelerator travel and retain low RPM torque and economy.

Regarding clatter and sounding like it's gonna throw a rod. My engine only sounded like that once, I think an injector got stuck. It was the loudest most horrific sounding noise like a rod was about to come through the block. Immediately pulled over and shut it off. Nothing obviously wrong and was fine when I fired it back up. Best I can figure is some small trash got into an injector and held it open so it fired way early.

 

Like I said before, the truck runs pretty good. I know the pump and injectors aint spring chickens anymore so, I'm thinking about playing with timing. Any tips on doing so? I havent messed with it before and don't wanna screw it up

 

See where it's set now and make a note of it. Set it to 9* at 2000 RPM and see how it compares to where it was, try 8* and 7* as well if you want a more thorough comparison. If the clatter is loud you may already be towards the more advanced side of the generally acceptable range.

 

Exactly! It sounds advanced already. What gains or losses will I encounter if I retard the timing a degree? More high end torque? Worse fuel mileage? Or should I just leave her be until I start seeing smoke and poor performance? I don't wanna fix what aint broke, just hoping to learn where the sweet spot is or if it's already there.
Thanks!

 

It's pretty darn hard to actually hurt anything, even 4+ degrees off, but when you get that far you'll /know/ it.
Just advance or retard it a little, see how she does.

If you want to just make really fine adjustments, see this:
https://www.youtube.com/watch?v=v6suazqvU_E
It seems to work pretty well overall; The timing curve changes if you use this method to adjust more than about 6 degrees off, but small changes it works great for.

 

Sweet! Thanks!

 

Perhaps advancing the timing is causing hard starts and therefore more glow plug run time is required to get things hot enough?

Just pondering at this point. I know mine is a bitch to start right now in the cold and it's partly due to whacked out timing. As such, I tend to run the glow plugs a few seconds longer (manual button) which seems to help. That could just be in my head though...