Hard cold starting

[abomb]

Hi guys, I have a 1983 D50 with the 4d55. recently replaced the timing belt, balance shaft belt, both adjuster pulleys, alternator, and glow plugs. also adjusted the valves.

The truck runs great, but starts rough in the mornings. I let the glow plugs go for about 5-7 seconds, then crank it. It fires right up, but then either dies or runs very rough. It sounds like maybe there’s a cylinder or two not firing, and there’s plenty of white smoke coming from the exhaust. Once warmed up, it idles perfectly with no smoke.
I know it’s an old diesel, but it seems like it should be starting easier in 70 degree weather. Could it be an injector timing issue?

[abomb]

I just realized the end half of the post is black. Copied it over from WORD. The last paragraph is below:
The truck runs great, but starts rough in the mornings. I let the glow plugs go for about 5-7 seconds, then crank it. It fires right up, but then either dies or runs very rough. It sounds like maybe there’s a cylinder or two not firing, and there’s plenty of white smoke coming from the exhaust. Once warmed up, it idles perfectly with no smoke.
I know it’s an old diesel, but it seems like it should be starting easier in 70 degree weather. Could it be an injector timing issue?

[drpbx911]

Hello Abomb, my experiences were similar when I got my first 4D55. For me I was unaware of the idle-up cable pull on the left side of the dash down near the hood release. Step on the throttle a little, pull the know out and turn the knob to the right to lock. Think of it as a choke, if you know what they were... HTH

[abomb]

my idle up knob doesn't seem to work. I usually stay on the throttle slightly while it's warming up, but it still smokes and runs rough until the temp starts creeping up.

[abomb]

well I got the idle up knob working, but it still smokes quite a bit on startup. is there a way to clean this up?

[royster]

I have no knowledge of first-generation OR diesel, but smoke on start-up is almost invariably valve seals...not a difficult operation, but time-consuming.

[geezer101]

What colour is the smoke? If it's white, it's indicating that it's not getting a full combustion burn (which is usually during a cold start)

[skullzaflare]

If i were to make a guess, id guess your compression is low, thus the unburnt fuel smoke and rough idle

[abomb]

The smoke is white on startup, and it has a rough idle. Once it warms up a bit it runs completely smooth.

[drpbx911]

FWIW, idle should be 750 +/- 50 once warmed up. I usually get my idle up to almost 1000 until it warms up then I can release the idle up. This takes much longer when it's cold out and it also runs worse when it's cold out - until it warms up. If you're uncertain of the maintenance history you might take a look at the valve adjustment and change the fuel filter. These are two areas that are easy to address and can make a big difference if they've been neglected for a while. The fuel filter is easy but a little pricey compared to a gasser. The valve adjustment might not cost you anything but an afternoon wrenching. All the information is available in the manuals that are available here online. If you haven't already checked out RockAuto.com for parts you should do that. They take a few days to show up but they have good prices and they have the correct parts for these trucks. Another thing you might check is ensure the glow plugs are working and they're all good. If they're all not working it might explain some of the smoke you see. Many of these trucks have converted the glow plug circuit from the stock timer to a push button in the cab. Before I found that I had issues with mine I was having starting problems and a lot of smoke once I got it started with a shot of gasoline. I installed the button and that solved the problem until I repaired it back to stock. I could hear the relays clicking and I waited until they un-clicked (?) before trying to start. I assumed they were working - they weren't. HTH