heavy blue smoke on start up !

[jpliddy]

happy new year to you all !
my D24 1995 has a lot of blueish smoke on start up theses wet and damp mornings in the UK , it does go away after a short time ,my engine seems ok when its warmed up, im back to thinking its the injectors need changing and the timing needs to be checked when the cam belt is changed in a couple of months ,
all comments welcome ,
regards jim

[ngoma]

Big cloud of smoke at startup at cold temperatures seems normal. You never noticed this beflre?

[jpliddy]

the car really juggs for a minute or so then it clears up assist its the cold damp mornings here as the car goes out most days ,

[ngoma]

Are all 6 glowplugs good and have you tried energizing them 2x before cranking?

[v8volvo]

Glow plugs for sure the right place to start with diagnostics, as even one dead one can make cold starting rough and smoky for the first 30-60 seconds. Two dead will make a real smoke show and three dead may prevent the engine from starting at all.

If you have access to an inductive ammeter (like the kind you can clamp around a wire), you can use one of those as a quick-and-dirty diagnostic step for the whole glow system. Nominally the "fast" Bosch glow plugs should draw about 12 amps each when running. So if you clamp your meter around the red wire that goes from the GP relay to the GP bus on the engine, then energize the glow plugs, you should read ~72A while they are running if all 6 plugs are good. If you read ~60A then you have five running and one dead. If ~48A then you have 4 good ones and 2 dead.... and so on.

It doesn't tell you WHICH plugs are working or dead but will at least help you determine if that is the right cause to pursue, without having to do the work of disassembling the glow plug bus and test each plug individually which can be labor intensive, especially for the back two. If your current readings indicate all plugs are functioning, then you can head in a different diagnostic direction unless you have already ruled everything else out. It is theoretically possible for a glow plug to fail in such a way that they still draw normal current but don't produce heat correctly, but that is fairly rare.

[jpliddy]

thanks for all the input , i replaced the glow plugs 2 years ago , but its possible that thats the area of the problem . the car fires up 1st time even in this sub zero weather we have here ,i energise the plugs twice as you suggested , it feels like its a glow plugs /wire issue , but it settles within a minute , and away it goes
diesel cars of this age and milage will have this sort of issues in this sub zero weather then?

[ngoma]

Your description seems pretty normal. Mostly it depends on the status of cylinder compression, glow plugs, IP timing and tune, and cold start mechanism.

[jpliddy]

hi thanks for your valued input, im stating to think about cold start device , i swopped this for another second hand device good few years back , i have a sore one on a spare injection pump , reason being im thinking this i started car this morning and outside temperature was 10 degrees C above yesterday it was 2 below C yesterday today 8 C not as much smoke plus I've noticed rev counter only goes up to about 900 revs on cold engine start up perhaps wax stat is shot too , i can test this in a saucepan of boiling water and see how far the wax stat plunger goes out in the hot water , is that correct ?

[ngoma]

Yes correct but much easier would be to take a clear photo of the cold start lever after the engine has been running and fully warmed up, and take another photo after the engine has had an extended cold soak. Or vice versa. Compare the lever position, that should tell you if the waxstat is functioning.

BUT: Doesn't a waxstat failure cause an "always on" condition? If the waxstat fails it will never allow the CX timing adv./idle speed increase lever to move to "warmed up" mode? So the IP will eternally be stuck in "cold" mode.

That's why those of us with failed waxstats have to disengage the end of the cable stop to let the engine run normally.

Properly tuned, the greenbook states there should be a 200 RPM difference between hot and cold idle speed.

[jpliddy]

thanks NGOMA
i have checked the travel of the cold start start cable i guess it travels about 9 mm , forwards and backwards so to say , but thats all i really know about this device