Technical Smoking kills vs DPF and Cataclean

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Technical Smoking kills vs DPF and Cataclean

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Having recently fitted a £££ new clutch and flywheel, and a new camshaft sprocket (damaged woodruff key made getting the valve timing correct a bit "hit and miss") I'm intending to get at least one more MOT out of Gerrard, before sending him off to a well-earned retirement.

The biggest obstacle I can foresee is the exhaust emissions. No matter what I do with the beast, there's more and more smoke every year, under MOT test conditions.

During normal driving, it's quite innocuous .. but if I accelerate at big throttle openings, or during the MOT test (which is the same thing) then it does a passable impersonation of a fire at a tyre depot. It's a bit embarrassing and I can see why Dr Death the MOT man is a bit moody about it.

Last time (January) I gave it a new air filter, several tanks of the Premium doodah Diesel, a bottle of some trick (all the labels were in German) fuel system cleaner and a dose of Ethyl-Hexyl-Nitrate for good measure. After several attempts, the good Doctor let it pass.. but it was right on the limit.

I've planned to get it Catacleaned for a year or two... but just never had time to get round to it... and this sounds like a no-brainer now, bearing in mind there's not much to lose.

But the Younger Mrs S. did ask why I didn't just put a DPF on it, to stop the smoke.
Appreciating that the car doesn't have a DPF and one of those requires a shed load of supporting equipment to work properly.. if the MOT Pixies bolted a DPF into my exhaust system, without any supporting infrastructure (so just using the DPF as a "filter") and all the sensor holes etc. were sealed, what would happen?

I presume that eventually the DPF would clog up, so the Pixies would have to remove the DPF again after the MOT .. but as a theoretical prospect (DPFs cost more than the car is worth)... would this work? ​



Ralf S.
 
Yes,the DPF would eventually clog and choke the car within a couple of hundred miles unless, as you said, you remove it after the MOT, or drill a hole through the centre, which is a common way of stopping it completely clogging, again as this is an expensive part, you might not want to consider such actions.

Assuming here that a DPF was never an option on this particular car, you might have to adapt an off the shelf part to fit, and they're big heavy buggers so they'll need supporting.

If you're getting that much smoke, and assuming it's black, you might have a boost leak which is where I'd start looking, check the condition of your turbo hoses.
 
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I'm sure my hoses are good. I removed the airbox and all the pipework just recently to replace the clutch, and I spent a lot of time putting everything back carefully, mostly because there are so many pipes down there that they can touch something, or each other and make a vibration or rattle.

A lot of the rubber pipes are a bit hard and less flexy than when they were new but they still fit reasonably snug and the clips are all new, or in good condition.

I'll have a nose in a few miles to see whether there's any oil mist around the joins. I fitted a new crank seal .. though the leak turned out to be from the corner where the sump meets the bottom of the crank seal. That oil leaking out would eventually mist out over the front of the engine and the turbo pipe work, so I could never be sure whether the hoses were leaking or if this was oil from the oil leak.

I'll have to definitely geta Cataclean, since the inside of the inlet manifold looks nasty.. but having degreased all the pipe work, intercooler, little box under the airbox and all around the turbo, I can be sure the beast is smokey because it's smokey.. not because of oil in the pipework (which it suffered from when I bought it.. overfilled sump).



Ralf S.
 
What you describe is perfectly normal the smoke is actually soot blown out of the exhaust during large throttle openings not so much when driving but when in neutral and revving hard.

Find somewhere quiet and give it four or five foot to the floor revs and it will then rev smoke free for a while.

What you are doing is the same as the MOT guy does during the test the first rev will be very smokey and will get better with each rev until all the soot is blown out and it will run clear.

I usually do this on the way to the MOT centre each year, my emission results are always low.
 
As above, black smoke is generally soot caused overfuelling, white may be unburned diesel, normally associated with clogged intake, leaky swirl flaps etc, or water in the combustion chamber, and blue for oil making its way through the intake or bypassing turbo seals.

I've seen a few hoses bulge and split when contaminated by oil so worth checking for anything soft or feeling a bit thin. Are you down on power at all, or low down grunt,m
 
What you describe is perfectly normal the smoke is actually soot blown out of the exhaust during large throttle openings not so much when driving but when in neutral and revving hard.

Find somewhere quiet and give it four or five foot to the floor revs and it will then rev smoke free for a while.

What you are doing is the same as the MOT guy does during the test the first rev will be very smokey and will get better with each rev until all the soot is blown out and it will run clear.

I usually do this on the way to the MOT centre each year, my emission results are always low.

I did give the beast a few runs around the local steelworks (I thought the haze would be blamed on the factory.. :D ) over a few days. The special brew with the German label made a bit of a difference.. but mostly the more I booted it, the clearer it got.. although the smoke test result was right on the limit, so I'm not sure how it will do this time.

If I get some warm weather I'm almost tempted to MOT it early.. the depths of January probably isn't the best time to get perfect emissions.. but then if it fails I'm knackered (the new MOT would over-rule the old one).

I'll save up for a Cataclean just before the MOT (but not "just" before it, in case a load of residual gunk ends up in the exhaust). I'm curious to try it anyway, just to see whether it really works, or is just snake oil. :)

Otherwise, I'll start using the Optimax Diesel for a couple of tankfuls beforehand, rather than just for the test.. :D


Ralf S.
 
Perhaps the maf sensor is slightly over reporting air flow?
If you have the tool to turn off yellow engine light perhaps unplug maf sensor and see if smoke is reduced. Not a definitive maf sensor check but could help.
 
Just to be clear driving at high revs wont clear the exhaust, it needs to be in neutral with a foot to the floor for a few seconds rev at least 3-4 times.
The view in the rear mirror should turn completely black so make sure you are away from people.
It sounds brutal but as long as the cam belt is good it wont hurt the engine.
I have had probably 15 different diesel cars/ vans over the years and they have all had this treatment and it works.
I wouldn't waste money on doctor feel-goods snake oils they rarely do anything.
 
Not sure the degree of relevancy, but I also have an old Chrysler with a 2.8 Iveco CRD engine, and when it got over 100K it started smoking a lot when cold, so much so that my local MoT man didn't like it.

My solution for the last couple of years was to give it a good thrashing over 25 miles or so, to make sure it was really hot. After said thrashing it ran fairly clear, and has passed the last 2 tests :D.
 
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