Smooth idle on WVO / Vibration at idle on B20... Why? - PeachParts Mercedes-Benz Forum

Blevinsax · #1 10-25-2006, 01:29 AM

The title pretty much says it all...

Fortunately *knock on wood* everything in my 350SD seems to be running well now and I've been driving the car everyday. I start the car in the morning, let it warm up to about 70-75C, then switch to WVO and drive. It runs pretty much perfectly on WVO all day - I do notice that it vibrates a little bit at idle when the temp gets up around/above 80C. When I get home in the evening, I switch back to purge and I can clearly feel the change back to B20 because the idle changes - I can feel it start bumping/vibrating/generally running a little rougher than it did on WVO. Nothing extreme - not nearly as bad as it was when I got the car back in June - but it is a noticeable difference because it runs SO smooth on WVO with virtually no vibration/rough idle (except a very little bit when the WVO is really hot - around/above 80C.)

Any ideas why this happens? I'm guessing it has something to do with the viscosity of B20 vs. WVO. What could I do to get it running as smooth on B20 as it does on WVO? Injectors? New Nozzles? Is it even something I should be concerned about - especially since I'm only running on B20 about 10-15 minutes per day?

Blevinsax · #2 10-25-2006, 01:28 PM

Any ideas? (Sorry for the bump)

F18 · #3 10-25-2006, 01:58 PM

Quote:

Originally Posted by Blevinsax

Any ideas? (Sorry for the bump)

My only thought...for what its worth.....is that the fuel viscocities are different, which would have some effect on fuel delivery pressure to the injectors. B20 would have a thinner viscocity than cold WVO so it flows easier at a lower delivery pressure. It might be indicating a problematic injector ( one that is carboned up).
Cheapist thing to do first is run Diesel Purge through the system and see if that has any lasting improvement on the way it runs on all fuels.
Good Luck!
Cheers,

Old300D · #4 10-25-2006, 03:25 PM

WVO will mask worn injectors. I had a '78 300D that ran fine on WVO, but would knock and rattle like crazy on diesel too. I believe the injectors were not in good shape.

Blevinsax · #5 10-25-2006, 10:09 PM

Quote:

Originally Posted by Old300D

WVO will mask worn injectors...

So, do you think this is something I need to address sooner rather than later? Is the 'masking' of worn injectors something that will cause major problems somewhere down the road? I've been enjoying driving the car since it has been running so smoothly but if it is causing harm to the motor, I should do something about it, right?

Mistel · #6 10-25-2006, 11:24 PM

I have a truck with a 2 tank WVO system and a 300td that I have been running 80%WVO/20%gas. Sometimes I will use straight diesel in the Benz and I notice that the car shakes more than with a blend. I believe it is because diesel contains more energy per volume than WVO and this causes the rougher idle. My observations after many miles in two vehicles is that diesels just run smoother on WVO

Peter

Knightrider966 · #7 10-25-2006, 11:33 PM

Quote:

Originally Posted by Blevinsax

The title pretty much says it all...

Fortunately *knock on wood* everything in my 350SD seems to be running well now and I've been driving the car everyday. I start the car in the morning, let it warm up to about 70-75C, then switch to WVO and drive. It runs pretty much perfectly on WVO all day - I do notice that it vibrates a little bit at idle when the temp gets up around/above 80C. When I get home in the evening, I switch back to purge and I can clearly feel the change back to B20 because the idle changes - I can feel it start bumping/vibrating/generally running a little rougher than it did on WVO. Nothing extreme - not nearly as bad as it was when I got the car back in June - but it is a noticeable difference because it runs SO smooth on WVO with virtually no vibration/rough idle (except a very little bit when the WVO is really hot - around/above 80C.)

Any ideas why this happens? I'm guessing it has something to do with the viscosity of B20 vs. WVO. What could I do to get it running as smooth on B20 as it does on WVO? Injectors? New Nozzles? Is it even something I should be concerned about - especially since I'm only running on B20 about 10-15 minutes per day?

It also has something to do with the fact that D100 (Dino diesel) has about 124,000 BTU energy release per cubid centimeter and WVO has about 115,000 BTU enegy release at same volume! Dino diesel has a flash point temp range of 175 degrees and WVO has a flash point of 300 degrees at the same operating conditions! Will make any Benz diesel rattle a little more! check out your injectors too if for nothing more than piece of mind!

pawoSD · #8 10-25-2006, 11:49 PM

When I ran my car off fry oil for a little while, I couldn't even feel or hear that it was running when at idle.

It was amazingly smooth and quiet...

tomnik · #9 10-26-2006, 02:14 AM

VO is burning slowly compared to diesel, at least if not heated up near coolant temps. This will be the same as retarded injection timing –> smoother. Also the burning time is increased. Heated VO can atomise similar to diesel and you should not have this difference.
Do you heat your VO? Where is your injection start?

Tom

Blevinsax · #10 10-26-2006, 02:37 AM

Quote:

Originally Posted by tomnik

Do you heat your VO? Where is your injection start?
Tom

Yes, I do heat my WVO with a GreaseCar system, but I'm not sure what you mean by 'Where is my injection start?' My coolant temp rarely goes over 80C - I saw it up to 90C last week when doing 80mph up the mountain at the Red Rock Canyon area of the I-215 beltway around the northwest side of Las Vegas - but other than that, it runs right around/just under 80C all the time since I had the cooling system overhauled back in August/September.

I am thinking of adding a VegTherm to my GreaseCar system to help bring the WVO up to temp sooner. That way I can burn more WVO/less diesel and I can be sure my WVO is not too cold going into the motor. What do you think? I am really happy that my engine temps are down, and I would like to keep them at/around 80C all the time if I can - especially since they were up around 110C earlier this summer before I had the cooling system work done.

It sounds like some attention is perhaps due for my injectors. I am not sure which way to proceed, however. The Bosio nozzles seem to be pretty high quality and consistent - and from what I've read here it seems the Bosch's are pretty hit-or-miss depending upon where/when they were built. Would the Bosio nozzles help my situation - or would I need complete new/rebuilt injectors? Can anyone recommend somewhere that I could purchase/order a set of new/rebuilt injectors with confidence that they will be really good? Approximately how much would a new set of 6 for the 350SD cost?

I understand that running on WVO *should* be the same and diesel/biodiesel if the viscosity (WVO temp) is where it should be. But am I doing any long term damage running on WVO now - and is that potential damage being masked by an illusion created by my 'extremely smooth running' motor???

tomnik · #11 10-26-2006, 04:00 AM

Yes, I do heat my WVO with a GreaseCar system, but I'm not sure what you mean by 'Where is my injection start?'

I do not know the GreaseCar system. I mean injection timing. Did you advance the timing of injection when converting to WVO?
Do you use greasy stuff or clear oil? In my opinion a set of new/rebuild injectors (pop pressure and spray tested) is the choice.

Tom

Blevinsax · #12 10-29-2006, 02:37 AM

Quote:

Originally Posted by tomnik

I do not know the GreaseCar system. I mean injection timing. Did you advance the timing of injection when converting to WVO?
Do you use greasy stuff or clear oil? In my opinion a set of new/rebuild injectors (pop pressure and spray tested) is the choice.

Tom

No, I did not adjust timing at all.
I use clean (triple/quadruple filtered to 2 microns) used canola and rice bran oil.
I am looking into a set up pop-tested and balanced rebuilt injectors as we speak (or type, as the case may be.)