smoky diesel

[ELAN+2]

I've got a 2.4td VW (LT28) six pot in my Volvo, after a period of cruising it chucks out gouts of smoke if accelerated beyond 3000rpm under load, it will do this a couple of times then be fairly smoke free for a while. It only happens at 3K and not all of the time, it doesn't make any difference if its on straight pump diesel or veg oil mix, regardless of ratio. I wouldn't bother normally, however I've been flashed a few times by other motorists when I've enveloped them in a huge cloud of smoke!

any ideas?

BTW new airfilter/fuel filter and running 15w40 oil, changed every 5000miles

[stevieturbo]

black smoke or blue smoke ?

They seem to ingest a lot of oil from the breathers, thru the turbo, into IC, then inlet manifold.
Well...mine does, although I dont have any smoke problems. I try to avoid going above 3000rpm though. It sounds bloody horrible !!!!!

You could maybe try blocking up the EGR too

[ELAN+2]

Steve, I've heard of the egr being blocked up on grey import Jap diesels but not on these, whats the benifit, if any and or the side effects, I know that on a petrol engine the egr allows the engine to run leaner on light throttle loads, hence reducing emissions and improving economy, the only benifit i can assume for the diesel is nox reduction?. As for over 3000 rpm, I get a glorious multi cylinder thrum and it goes like stink..........well considering its bulk and the fuel type!!LOL

[stevieturbo]

ELAN+2 said:

Steve, I've heard of the egr being blocked up on grey import Jap diesels but not on these, whats the benifit, if any and or the side effects, I know that on a petrol engine the egr allows the engine to run leaner on light throttle loads, hence reducing emissions and improving economy, the only benifit i can assume for the diesel is nox reduction?. As for over 3000 rpm, I get a glorious multi cylinder thrum and it goes like stink..........well considering its bulk and the fuel type!!LOL

Basically it allows stinkng crud into the inlet manifold, as thats all that comes out of the exhaust on a diesel !!!! lol

Yours sounds glorious ???? must be a different 2.4tdi than is in my Volvo lol, and mine sure as hell doesnt go like stink. I even went to teh trouble of fitting a smaller exhaust housing, and tinkering to make it respond better low down ( its an auto too ).
It all helps, but its no rocket, and I hate revving it !!!!

[ELAN+2]

mine really tramps on, its a manual and really pulls well from 2500 as the turbo spools up(you can even hear a faint whooosh) it revs all the way to the cut out at 5000, en route at around 3000 it dumps a cloud of muck black/grey coloured smoke out the back though!! Could that be the egr opening? I guess it is either operated by vacuum or boost/ combination of the two?

[stevieturbo]

On mine, I simply fed a boost signal into the top of the EGR, so it will never receive vacuum to open it.
Although of late, I removed the link pipe, and bolted a plate to the exhaust manifold. Mainly as I wanted to stick an EGT probe in there for a nosey.

Black smoke defo sounds like excess fuel.....cant say why yours is doing it though. After I adjusted the screw on the pump a little to give me more fuel, mine would give a puff of black smoke occasionally on a hard accel from standstill, but generally, it runs very cleanly given its a crappy old diesel.

I think mine is actually redlined at 5000rpm...dont think Ive ever ventured that far though !!!
Before I changed the turbo etc, mine was very laggy down low. Nasty pulling away from junctions with the auto. After the mods, it is far far better.
With hindsight, I probably should have sourced a GT15/17 type turbocharger for it, instead of retaining a T3 based unit, although the GT would be a T25 size flange, and have required downpipe mods.


God Im sad...I cant believe Ive modified a diesel volvo !!!!

[ELAN+2]

stevieturbo said:

Black smoke defo sounds like excess fuel.....cant say why yours is doing it though.


God Im sad...I cant believe Ive modified a diesel volvo !!!!

I don't think you are sad at all! I'm running mine on used veg oil that i get for free! now that is very pikey and there fore sad!

I had a play with the fueling screw on the pump and have eliminated the smoking, it's a bit lumpier on idle but seems to still pull well and no more smoke, it's not so keen to rev out now but i rarely take it beyond 3500 any way. According to the tech sheets the auto should be even more economical than my manual, I'm getting around 38mpg average (43 on a long run if i drive like a nun!)on a mix of used veg and derv, so I'm quite happy. These are lovely old motors, I'll be sad to see mine go when I've finished with it.

Mark

[760TD]

I definitely get the 'thrum' with our 760td (auto), but I'm pretty sure I'm not getting 38mpg... maybe too much thrum!

[ELAN+2]

760TD said:

I definitely get the 'thrum' with our 760td (auto), but I'm pretty sure I'm not getting 38mpg... maybe too much thrum!

according to the official govt figures the auto 940 diesel is more economical than the manual! Not sure of the 7 series though.

sadly mines got to go as I've got another company car, I'll really miss the old girl.

[stevieturbo]

ELAN+2 said:

760TD said:

I definitely get the 'thrum' with our 760td (auto), but I'm pretty sure I'm not getting 38mpg... maybe too much thrum!

according to the official govt figures the auto 940 diesel is more economical than the manual! Not sure of the 7 series though.

sadly mines got to go as I've got another company car, I'll really miss the old girl.

Id say I average about 31-33mpg at best. By no means an economical car. But it is comfy

[ELAN+2]

stevieturbo said:

ELAN+2 said:

760TD said:

I definitely get the 'thrum' with our 760td (auto), but I'm pretty sure I'm not getting 38mpg... maybe too much thrum!

according to the official govt figures the auto 940 diesel is more economical than the manual! Not sure of the 7 series though.

sadly mines got to go as I've got another company car, I'll really miss the old girl.

Id say I average about 31-33mpg at best. By no means an economical car. But it is comfy

You guys must have heavy clogs!! On a round trip to Leyland from Daventry the old girl did 36mpg and regularly sat at around 900 leptons or whatever! As for comfort, old Volvo's knock most modern motors into a cocked hat, it seems that todays cars have a too firm/jiggly ride and a lot more tyre noise (i blame low profile rubber for this). Theres not a great deal on the road that can with the carrying ability, Double bed? no probs, 8'x4' sheets of plaster board? a dozen at a time? no problem(ok, 18" hang out the back!), And for the disposal of old kitchens,bathrooms and other building debris? Perfect! With the added advantage of not needing permission/a special license from the local council to tip, unlike a van/pickup!.

[wwwfairness4fans]

Did you manage to solve your problem re: blue smoke at 3000 revs?

• maybe its worn valve stem oil seals
• Throtle body
• or fuel filter?

My Ford Fiest Zetec is doing the same.
It has failed MOT for emissions - a large cloud of blue smoke at 3000 revs.

yet...
Oil level is ok
its ok at 2000 revs and 4000 revs
it is fine whilst driving at 3000 revs

its just at 3000 revs when idling (after 30 secs - blue smoke commences)!

I'm not sure what it is - anyone any other ideas?

[BB-Q]

Blue smoke is usually due to the turbo seals. Black smoke is the engine running slightly rich. Diesels have the same stoichiometric ratio as petrol (14.7:1), but belch out black smoke if they ever get anywhere near that ratio.

[ELAN+2]

problem was solved by turning down the fuel pump a bit, being and older style diesel its still a bit smoky but not horsing out great gouts of choking black stuff as it was before!! I've not noticed a decrease in performance but it does seem to be a tad more economical!