[MAnd]

Hi, I recently bought a 2018 855D, it has only done 250h. It has an issue with white smoke on start up. It only lasts for a minute of so. First thought was a glow plug. Found the faulty one and replaced it. Now the engine started clean, then about 15 seconds later it coughs, runs rough and blows white smoke for the next minute before fixing itself and running smoothly. Happens every time the engine is cool. Has me scratching my head. Any thoughts would be helpful.
Thanks Michael

 

[200mph]

Do you allow the glow plugs to cycle off before starting?

Could be another GP is weak or not getting full current to GP during on cycle. If resistance in wire circuit the GP will not reach full temperature. Wiring integrity or the ability can be tested along wiring circuit. Put lead on batter POST (not clam terminal) and other on GP. Voltage when on should be 0.2 volts or less.

also could be fuel related if you don’t turn over fuel or buy winter diesel in cold climates. Diesel is hydroscopic so it absorbs moisture.
Before getting too deep into this consider draining all fuel and refilling with fresh.

 

[MAnd]

Yes of course

 

[MAnd]

Do you allow the glow plugs to cycle off before starting?

Could be another GP is weak or not getting full current to GP during on cycle. If resistance in wire circuit the GP will not reach full temperature. Wiring integrity or the ability can be tested along wiring circuit. Put lead on batter POST (not clam terminal) and other on GP. Voltage when on should be 0.2 volts or less.

also could be fuel related if you don’t turn over fuel or buy winter diesel in cold climates. Diesel is hydroscopic so it absorbs moisture.
Before getting too deep into this consider draining all fuel and refilling with fresh.

Thank you, I replaced all the GPs, so would be surprised if it was those, but I'll will check resistance as suggested. As for fuel, it was changed and have since used a few tanks full. Also it has been summer here so warm weather starts 20-30º celsius.

 

[200mph]

It wasn’t clear by first post that all three were replaced, so agree they are not likely the issue.
The voltage drop test has helped in uncovering wiring issues with the GP circuit before and is easy to do. If unfamiliar with test, search voltage drop test for starters as there a number of good videos describing the intent and general process.
Keep us posted on what you find.

 

[dane]

How is the machine used? If it idles a lot or spends a lot of time with a light load the engine can load up with carbon deposits. These can get knocked loose during startup making white smoke. You can try taking it out and drive it like you stole it for at least 15 minutes but longer would be better. Put it under a load and give it hell. You want to make the engine work and get as hot as it will get. Then see if the problem still occurs. You may need to take the machine out every week or two and give it a solid workout.

 

[200mph]

FYI...

From GP product literature I happened to be reading...

Here's a link to the literature. It gives a good overview of modern GP's. All about Glow Plugs (d1c96hlcey6qkb.cloudfront.net)