Smoke on cold start up.

We have a older DAF 12,6l engine.
This is the predecessor to the Paccar 12,9 l engine.
We had an issue with a bad batch of coolant.
This truck developed a leak on a welsh plug and and had a localized overheat on the one head.
We decided to just do a complete in-frame inline.
We had all the injectors done as well.
Truck runs good , as is the diesel usage.
The problem is that on early morning start up there is a lot of white smoke.
There is also a slight combustion knock sound at start up while it smokes.
After about a minute of idling it goes away completely.
It then wont do this the rest of the day.
If the truck is left till about 10am before starting and outside is a bit warmer no smoke at all.
It went in to the agents who said they found nothing wrond and it did not smoke with them.
I know it parked inside and they only looked at it after 10am so that does not surprise me.
Does anyone know if this engine has some sort of cold start unit?
If it does could this play a part in this?
I must add that it does not get very cold here.
Never under 32F .

 

White smoke.
Injectors just all redone.
I suspect there may be an issue with one of the new injectors.

 

That is what upsets me.
The truck was at DAF for 4 day's and they said they could not find a fault.
We don't have our own Davie , so sent truck to DAF.
I know they only looked at it after the day had warmed up.
I guess I will just send it back.
As for the injectors they were supplied by DAF so they should be OM.

The problem is we are just to busy to take trucks off work.
I just don't want to lose an engine , as I say only smokes for a short while.

 

That's true.
We don't have many experts here.
As I have said before , you could make a fortune here.