Really loud on cold start

[Bob H]

'84 M1009 60k on the clock

Apologize in advance if there's an easy to find thread on this issue, I searched, because I know it must have been covered here.

On cold starts, this things is scary loud clanking.
Quiets down after the fast idle(<-- wrong terminology) kicks off. Once warm it runs just as smooth & quiet as can be. (it is a 6.2)

Been a gasser guy, fairly new to this diesel stuff. Could this be an injection timing issue?
or should I be on the look out for a rebuild/new engine.

 

[firefox]

I would check all the glow plugs first, before worrying too much. If the truck
is new to you, then I would just replace all the glow plugs with AC60Gs just
to keep from visiting that problem in the future. Even if that doesn't turn
out to be the current problem. Check the CUCV stickies for further tips if you
haven't done so already.

 

[m38inmaine]

In the cold start cycle the timing is advanced so it sounds "knocky" until it kicks down off high idle.

 

[rsh4364]

I remember my first coldstart experience,scared the heck out of me.I turned it off thinking I blew it up.I have learned a lot since then.I now run Rotella T-6,starts are much quieter now.Wait til you start it at -10 degrees.Really loud.

 

[Barrman]

Fast idle is the correct terminology. Two things happen when the coolant is below 95° in a properly working system.

The green wire at the IP has two ends. One of those ends goes to a solenoid inside the IP. That is the cold advance solenoid. It advances the timing to aid the engine in starting.

The other end on the green wire goes to the fast idle solenoid which is the round thing stuck up in the air next to the IP. When the driver turns on the ignition, the system is below 95° and pushes the throttle down an inch or so. The fast idle solenoid will hold the throttle open just a bit. Factory numbers on the air cleaner say 650 rpm warm and 800 rpm with fast idle.

The loud noise is almost all due to the advanced timing. The manuals don't state this, but driving easy until the advance turns off it probably a good idea.