The Smoking MAN

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Spong

Spong

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Location
Surrey / Hants border
No, not the one from the X-Files, but our horsebox......hopefully this is a good place to post this appeal for ideas and suggestions.
The Vehicle
1994 MAN L2000 / 8.153, which is a 4.6l 4-cyl turbodiesel.

The Problem
A few months ago it started smoking from cold. Starts readily and at idle there's 'thin' white smoke, not a lot but it's there, but bring the revs up a little (say, 1500rpm) and there's thick, opaque white smoke which will sting the eyes if you're dopey enough to stand in it. If you take it out for a run and get it warm, it stops smoking (it has just passed it's plating in this condition!).

What's been done so far
Replaced turbo - we suspected the smoke was caused by oil ingestion at first, so started with just an inspection, but found the compressor blades were badly damaged by nut/bolt/stone getting in the intake and, as the exhaust end was rusted beyond belief, we replaced it.

Injectors removed for testing - found to have no problems, other than showing their age a bit. The idea is to do a compression test before the injectors go back in.

That's about all we've done that's relevant to this problem. Now, from what I've read, I believe this smoke is unburnt diesel and not oil (but happy to be corrected). If that's true, I just can't think why it would be overfueling until it got warm. Any ideas?
 
Now nowt about that engine or that lump but I had the same symptoms on my motorhome.
Mine was also very lumpy on cold start for 20secs or so. Getting the injectors refurbed cured it a lot but the issues you are having were still evident. Turned out to be a badly out of adjustment cold start thing on the side of the pump. Still does it a bit which does get progressively worse if left idling, drive off straight away and it's fine, no problems after that for the rest of the day.
I had fuel dripping out the tailpipe before the work was done and 18mpg, now 23mpg.
 
Is there a form of cold start on this engine? not glow plugs.
This may add more diesel on start up. This may be sticking

Try @lynall I think he is a trucky tecky(sorry if I'm wrong ;))
 
Never knew MAN made a diesel that small, but you live & (hopefully) learn.
Whatever you do don't use spray cans (ie Easystart) on it, no matter how difficult it is to start :eek:
 
has it got a thermostart going into inlet manifold idont expect it has don't know this model if it has some times they can leak diesel into inlet manifold if it has the bes way is to block fuel feed to thermostart and see if smoke improves ithink I spelt thermostart wrongly
 
Thanks for the replies - sorry I didn't get back on sooner...
After more prodding about we think the cold start auto advance thingy on the injection pump (Bosch VE4) might have something to do with it. It's not one that senses the coolant temperature directly as it has no pipes to and fro. There is a stud and nut type terminal on the rear end, but no wire attached. There are, however, two wires floating about nearby that could reach it - one has 24V on it, the other 0V.
So how does this work? Is there a normally closed thermostatic switch somewhere that supplies 24V to the solenoid until the engine temperature comes up, them opens and let's the advance go back to normal?
I'm loath to dab the 24V wire onto the terminal in case I stuff it up further, at least not until I know it supposed to be there! I'll put a pic of it up later...
 
So here's a pic of the back half of the pump. The top cylinder is the pneumatic stop cylinder, and the lower, mostly black one is the 'cold start advance control' (or KSB as Bosch call it). You can see the terminal on the end, and just see the two loose wires in the bottom right hand of the pic - the only electrical connection nearby that either of them would reach is that terminal...

pump1.jpg


8ha said:
has it got a thermostart going into inlet manifold idont expect it has don't know this model if it has some times they can leak diesel into inlet manifold if it has the bes way is to block fuel feed to thermostart and see if smoke improves ithink I spelt thermostart wrongly
Click to expand...
Yes it does, and we did wonder about that. Do you think it would leak continuously until warmed up, or just enough to cause a puff of smoke on start up and then clear?
 
@Flossie , @Hicap phill , @Bobsticle , Yes, cold start advance is currently my prime suspect for this environmental crime....
Al2O3 said:
You're not losing coolant then?
Click to expand...
Doesn't seem to be, we've checked both that and the oil, doesn't seem to have changed levels of either.

Here's a pic of the lump itself, the 'thermostart' (if that's what it is...) can be seen at the start of the intake manifold, with a white wire attached. Worth taking a look at that too.

lump.jpg
 
Spong said:
Yes it does, and we did wonder about that. Do you think it would leak continuously until warmed up, or just enough to cause a puff of smoke on start up and then clear?
Click to expand...

Thermostarts can fail any which way IME :mad::mad::mad: - the smoke is a good indicator - but your KSB needs sorting too, but Fuel consumption will increase quite a bit in the worst case scenario .... easy enough to block the fuel supply to it orft .... and see what happens.

I know nothing about trucks - but is there an online manual for this thing ?

I had a thermo fail on a tractor end of last year - failed fully open, and the thing turned into a smoke machine :eek: - actually half hydrauliced the engine at one point, all the diesel ran into the sump ..... its nice and clean in there now tho :rolleyes::D:mad:

If it is the thermostart, fit a decent quality one :rolleyes: - I know I'm preaching to the converted here, but the cheapo ones are cr*p :rolleyes:
 
Disco1BFG said:
but is there an online manual for this thing ?
Click to expand...
Frustratingly no, all I can find for the truck is a very comprehensive document detailing everything you might need to know about putting a body on the chassis, but sod all about how the truck itself works. I have found a Bosch manual for the pump, but it doesn't go into detail for the cold start advance.
 
Spong said:
Frustratingly no, all I can find for the truck is a very comprehensive document detailing everything you might need to know about putting a body on the chassis, but sod all about how the truck itself works. I have found a Bosch manual for the pump, but it doesn't go into detail for the cold start advance.
Click to expand...

Charming! :mad: How about ringing the likes of diesel bob - or similar ? I found him very helpful when I took EDC off me D1 ..... even though I didn't spend any money with him ...... yet ( might need a FIP rebuild in the non too distant :( )
 
Had another look at it last night, I wanted to confirm that moving the advance lever would affect the smoking. Started it up, brought the revs up a tad from idle, which is when it gets really smokey, and then moved the advance lever - and the white smoke stops (well, at least below major embarrassment levels anyway). Did it several times, so I'm sure now that's the problem.

What I don't know is how the actuator for it works. I have seen stuff on the net showing a unit just like it that works on a 'waxstat' principle, and gets 24V to a heating element while the engine is cold. This makes the wax expand and squeezes a rod outwards - when the engine is up to temp the supply is removed and it cools and contracts again. But the one I have needs to pull the lever towards it, so it's not a waxstat type.

Mine has a short length of bowden cable connecting it to the advance lever (under the rubber boot in the pic above), so I think it must be a solenoid that pulls the cable towards it. Checking between the terminal on the end and earth shows it to be open circuit, so if it is a solenoid, it's stuffed.

Supposed I'd better go and see what I can get from the dealers, but I suspect it will be 'you have to buy the whole pump mate'!
 
I can't find any info about it anywhere so far, including Bosch, at least the dealer will have the diagrams etc - I don't have to buy anything. if I can con the part number for it out of them I may be able to find it elsewhere..
I've no clue who Diesel Bob is....
 
when lorry starts from cold on a cold morning does it fire up on all cylinders or does it mis and smoke white smoke and graduly fire on all cylinders when fully warmed up take off engine oil filler cap and see how much blow by it has some times low compression can cause this have yoy tried when hot losing injector hp pipe one at a time and see if smoke is general or les evident when one pipe is losend I am not fimilar with this engine can you try moving injector to alter timing slightly how well does it pull have you puled off pipe from turbo to inlet manifold to see it is only slightly damp ithink you said you fitted a new turbo but even new ones can be faulty with pipe pulled off run engine and see if it makes any diferance to smoke there some other things most unlikely like cam lobe going flat tappets out of adjustment or injector pump a bit worn so the timing is slightly retarded broken piston ring bore wear if you can I would definatly try advancing timing slightly
 
Last edited:
We were going to do a compression test while we had the injectors out for testing, but my mechanic man didn't have the right adaptors for it. However, as I mentioned above, manually advancing the pump timing with the advance lever does stop the heavy smoking, so I think that would be my best line of attack.
 
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