Veg oil - injectors noisy when cold, OK when hot - 4000 miles

[pcman_jh]

I have a 2 tank system (diesel for cold starts/ main tank with 90% veg oil) on my 1999 E300.

I got the injectors refurbished about 4000 miles ago as they were generally noisy.

I'm now finding they're getting noticeably noisy again with the first cold start of the day (on diesel, but you can smell there must be a residue of veg in the fuel still), but once heated up and turned to veg oil they're fine. Apart from the noise the engine runs fine, both hot and when cold.

Should I be too worried about this or is this just a winter symptom. When I was running on 50% with a manual mix at cold (before the 2 tank conversion) I didn't notice this 'louder' noise when cold.

I'd describe the noise as a light tappety noise (rather than serious knocking).

Any thoughts?

 

[Parrot of Doom]

I've just replaced the fuel line clips on the cylinder head. You can see them, follow the lines from the injector pump up to the injectors. Each clip holds 2 lines.

Mine were all broken/weak. They're only cheap, and it might be part of the noise.

 

[Glenn Smith]

I have a 2 tank system (diesel for cold starts/ main tank with 90% veg oil) on my 1999 E300.

I got the injectors refurbished about 4000 miles ago as they were generally noisy.

I'm now finding they're getting noticeably noisy again with the first cold start of the day (on diesel, but you can smell there must be a residue of veg in the fuel still), but once heated up and turned to veg oil they're fine. Apart from the noise the engine runs fine, both hot and when cold.

Should I be too worried about this or is this just a winter symptom. When I was running on 50% with a manual mix at cold (before the 2 tank conversion) I didn't notice this 'louder' noise when cold.

I'd describe the noise as a light tappety noise (rather than serious knocking).

Any thoughts?

Do you switch back to diesel before you switch off? you're probably starting on veg oil if not, could be the cause of more noise.

 

[pcman_jh]

I always switch back to diesel, otherwise you get really lumpy starting, not just noisy!

 

[Hibbo]

Are you sure the noise is the injectors? Could it not be the hydaulic tappets needing hot oil to operate quietly?

Does it sound like an injector 'nailing'? I think this happens when an injector doesn't open properly and a standing pressure wave is developed in the pipe. This can easily be felt by holding each injector line in turn.

Try cracking each injector union in turn to see if the noise stops.

Try a dose of injector cleaner, although I wouldn't expect it'd need it after so few miles since reconditioning.

Who did the reconditioning and what exactly did it entail?

I am still not sure the noise is from your injectors though...