PDA

View Full Version : Excessive smoke



bruceT
9th November 2006, 06:54 PM
Just lately I've noticed an increase in the amount of whitish smoke coming from the exhaust of my 300D when I'm waiting at the lights and running on veg. The car does not smoke when under load and cruising, just when idling for a while. The longer it idles, the worse it is. The smoke disappears if I switch back to diesel.

It's starting to embarrass me a little as it swirls around all the other cars waiting at the lights, and there's no guessing where all the BBQ smoke is coming from!

I'm just wondering if I should adjust my timing.

Any ideas?

I'm running on cold-filtered wvo (cottonseed oil). I have a 26-plate HE before the fiilter and a glow plug heater before the IP.

Captain Echidna
9th November 2006, 09:13 PM
Sounds like unburnt fuel. With mine I cant start on a blend, as it shoots great clouds of the stuff out when it (eventually) fires, but once warm, its reasonable.

Fitian
10th November 2006, 12:10 AM
Bruce,

Sorry to hear you are having some trouble. Could it be a bad batch of oil? Have you tried adding some injector cleaner or fuel treatment? I do not know how the GP heater works but this is the last part you added to your car conversion .. right? could it be related? when you say adjust the timing do you mean adjust the valves? if yes then do you think using vegy oil needs a different valves adjustment?

I hope you get on top of this quickly.

All the best

Fitian

tbird650
10th November 2006, 06:55 AM
When that has happened to me, each time it has turned out to be coked injectors. Cleaning the nozzles has become a monthly ritual, though I have my fingers crossed I've cured it by running hotter, thinned oil. My targets are 80c and 20% diesel/petrol. When I take the injector out it doesn't look too bad, but look in the hole where the injector seats, and it's almost completely choked off with carbon. There is only a pin prick of a hole through the carbon for fuel to squirt through!!
.....And what a difference a clean injector nozzle/port made to the power!!
It appears to me that your Merc is a bit more forgiving of higher viscocity oil than my rotary pump injected Toyota?
Another part of my puzzle is that it appears that the CAV296 filter won't pass enough vege on the open road, though heated to 60c, unless I thin with 20% petro-diesel.
I hope you get your problem sorted quickly as troubles of the kind are alarming and frustrating. Good luck.

bruceT
10th November 2006, 10:51 AM
Thanks everyone for your thoughts...

I have been wondering whether a higher viscosity fuel would require a more delayed timing setting, so that the burn occurs close to the instant the injector commences to spray?

The fact that I get no smoke from diesel would seem to indicate it's not an injector problem. However, I might remove one on the w/e to check anyway.

Fitian has also alluded to the GP heater so I might try disconnecting it to see if there is any change to the amount of smoke. It is possible that the oil is being heated more by the GP at idle because it spends more time in contact with the GP, and this may be causing polymerisation of the oil. I believe that this this would indeed cause more smoke.

I have recently insulated everything including the CAV filter, and with the onset of warmer weather, the fuel temp at the IP may have risen too much. I'll take some measurements to see. I have a 100degC thermostat on the GP heater, so I might have to try a 90deg one instead.

Fitian
10th November 2006, 11:31 AM
Bruce, I hope you can put your hands on the problem this week end.

I also want to share with you that I have just added a twin coil heat exchanger to the conversion of my 300D. One coil adds more heat to the oil before the valve and the other coil is working after the valve and right before the lift pump. I could have used the first coil for the return but I thought I'd be better with adding more heat to the 20 PHE.

With this twin coil HE I could switch to vegy oil a lot sooner than before. The smell is even nicer. I think this has done the trick for me.

Here is how things look right now...

http://www.members.optusnet.com.au/~cncbrog/Helton HE.JPG

Here is a link for where I got it from.

Biofuel (http://www.helton.com.au/biofuel.htm)


Cheers,

Fitian

Tony From West Oz
11th November 2006, 12:23 AM
Fitian,
A neat installation. Do you have a diagram that you could post here for us to see how it is connected?

Tony

Fitian
11th November 2006, 02:48 AM
Fitian,
A neat installation. Do you have a diagram that you could post here for us to see how it is connected?
Tony


Tony,

Thanks for your kindness you're the teacher.
I will draw how things are connected and post it soon.
What do you think is the reason for the white smoke in Bruce's car?

Fitian

bruceT
11th November 2006, 09:22 AM
Hi Fitian

As Tony has said, it's very neat, and if it works well, well that's the whole aim of the exercise hey?

All you need do now is insulate the hoses. Clark Rubber will have the stuff for that job. Try to get the type that is already split. Otherwise, just split it with scissors and glue it closed when installed. It's what plumbers use for hot water pipes.

For the CAV, a sleeve made from a stubby holder with the bottom cut off works well.

Good job!

Cheeky
11th November 2006, 09:46 PM
Hi Bruce,

I have had similar problems before with my Mazda Bravo and IMHO I wouldn't disregard your injectors, the problem I had was caused by cross contamination which occurs with the simultaneous switching of supply and return when 6 port Pollak valve changes switches back to diesel. It would worth draining a sample of your tank diesel and compare it with new stuff, if it looks more like veggie than diesel I'd suggest you change the way you are using your diesel tank i.e. shorter fills at higher frequency.

The other alternative is to change your valves to two 3 port and sequence them so the contamination does not occur and the pump and lines are purged with clean un-contaminated diesel every time.

Anyway, your problem may be nothing like this, but I've experienced this before and it cost me a lot of time, frustration and at least $600 and thought my post might save you something.

Regards,

Cheeky :D

Fitian
11th November 2006, 11:00 PM
Hi Cheeky,

I am just wondering with many wvo users no one ever complained of such smoke even though most of them are using the 6 port Pollak valve!! You could be right ... I am here to learn.

I have a feeling that the GP heater is over heating the oil before the IP. The last few days the weather was warmer and I think this helped for the oil to stay hot and not to lose as much heat this is why the GP was an over kill. I noticed very little amount of white smoke this afternoon while idleing too and I think my extra twin coil heater is also doing the same thing but it is not as strong as the GP heater that Bruce installed.

I guess Bruce will tell us how did he go today.

Regards,

Fitian

Tony From West Oz
11th November 2006, 11:40 PM
I also have a car which has some white smoke when idling (and also while driving, but not as bad). I believe that the injectors may not be injecting correctly. I would also like to upgrade the nozzles to those used in my '84 300D as they seem to work better in each of the 300Ds we have, than the ones in the '78 engine.

It may be time to speak to an injector service technician.

Tony

Fitian
12th November 2006, 10:11 PM
It may be time to speak to an injector service technician. Tony

So you do not think over heating the vegy oil would cause a white smoke?

I will see where to find a technician near me.

Cheers

Fitian

Tony From West Oz
12th November 2006, 11:19 PM
No, I believe that overheating the veggie oil will cause it to decompose, resulting in the oil charring and blocking the fuel lines, injector pump and/or injectors.

Remove an inspect your GP heater. Is there a build-up of carbon on the GPs? Can it come off easily? Do you have a fuel filter to catch these pieces so they do not enter the IP?

bruceT
13th November 2006, 05:13 PM
No, I believe that overheating the veggie oil will cause it to decompose, resulting in the oil charring and blocking the fuel lines, injector pump and/or injectors.

Remove an inspect your GP heater. Is there a build-up of carbon on the GPs? Can it come off easily? Do you have a fuel filter to catch these pieces so they do not enter the IP?

I have a clear filter after the GP heater to catch any carbon, just in case. So far it remains nice and clear, so no nasties getting through.

I didn't have time on the w/e to do much on the car except check the GP heater. It was fine, with only bare metal and no carbon. I take pains to ensure that there is no air in the heater body for that reason, so really wasn't expecting to find anything but it's a relief anyway.

I'm inclined to do an Italian tune-up on diesel, but don't want to do this without inspecting the injectors first. I've got a noisy cv joint to attend to and some play in the font suspension to sort out this week (I think tie-rods), so I'll have to wait until this w/e now to check the injectors.

Cheeky
14th November 2006, 08:50 PM
Hi Fitian,

I'm not saying for sure the Pollak 6 port valves the problem but just that I have had a similar problem myself and only solved after understanding that cross contamination was occurring and modifying the use of my diesel tank to minimise the level of contamination. If you do a little searching and reading on some of the US sites, particularly Frybrid, you'll find a lot of those guys try to get almost zero veggie in their diesel.

Anyway, I'm not bagging the use of Pollak 6 port simply highlighting cross contamination, and I'm still using my 6 port at this stage. For the sake of the excercise it's worth draining some tank diesel and and comparing the colour with what you get at the bowser, also worth putting your samples in the fridge/freezer to see if it gels or worse still in my case, set solid......:eek:

Regards,

Cheeky

bruceT
16th November 2006, 07:55 PM
Hi Cheeky

Thanks for your thoughts. However, the Pollak valve would have nothing whatever to do with causing the smoke while running on veg oil. I don't have a problem when it runs on diesel at all. It will smoke while standing at the lights even after a good 30 minute oil run at 90km/hr, but the smoke disappears within 60 seconds of switching back to diesel.

While some cross-contamination occurs with any setup to some degree, with my system I can safely say it's so minimal that it's not worth worrying about. I fill my tank with diesel and it lasts me approx 2 months (About 4000km). The diesel in the clear filter is still clear after all this time.

While I'm suspecting the GP heater more and more, I'm looking forward to having a look at the injectors, although I did not check them before starting to run on oil, so I won't really know if they're any worse than they were. In any case they're probably due for a service anyway!

Fitian
17th November 2006, 10:24 AM
While I'm suspecting the GP heater more and more, I'm looking forward to having a look at the injectors, although I did not check them before starting to run on oil, so I won't really know if they're any worse than they were. In any case they're probably due for a service anyway!

Hello Bruce,

If your thinking is getting you to point the finger at the GP heater then how about placing a pre filter after it abd before the injectors? It will only cost you a $3 filter and a couple of clamps. Or change the thermostate so it switchs off at lower temp. Also if your engine runs perfectly normal on Diesel then the injectors are working fine. Don't you think?

After installing this new twin coil heater, I started to notice some white smoke at idling after a long run. It is not that bad though. It actually sends the aroma of fish n' chips all over the place :) .

Best of everything

Fitian

Captain Echidna
17th November 2006, 09:42 PM
I guess vegetable oil being harder to spray would be the reason it smokes on veg and not diesel. Perhaps as the combustion temperatures drop when the car idles, this causes the spray to burn worse, causing the temperatue in the combustion chamber to drop further.

I have no idea if my merc does this as it does not spend too much time in traffic. By the time its hot, I am out of town.