Oil for older MB 300SD?

[Tornado Red]

Originally Posted By: JHZR2
In MB manuals for those sold in the tropics, the manual states that palm oil is an acceptable substitute for diesel fuel.


It will work, but I would not describe it as a good choice. On the plus side, vegetable oil works okay in indirect injection engines, where the fuel and air are mixed before being blown into the combustion chamber. On the negative side, there is still the potential of contaminating the engine oil, so your fuel savings could be negated by the higher cost of oil changes.

 

[jmaster]

Originally Posted By: Tornado Red
Originally Posted By: jmaster
Originally Posted By: JHZR2
Nope, run a 5w-40 diesel spec. Youll need an older w123/126 with a 616/617 engine to do what you are saying.

Id highly recommend blends versus trying to run straight. You can do more damage than good sometimes.

whats the difference? the injector pump? the nozzles? why couldn't i run veg oil?

You would need a two-tank system, starting on #2 diesel and then switching back to it before shutting down the engine. If you try just pouring veggie oil in the regular fuel tank, you would be asking for some serious and expensive trouble.

i know i need to have a separate tank for the veg oil and to heat the veg oil, start on diesel fuel ect. i know the veg oil has a higher viscosity and glycerin in it. why would i "need an older w123/126"?

 

[Tornado Red]

Originally Posted By: jmaster
i know i need to have a separate tank for the veg oil and to heat the veg oil, start on diesel fuel ect. i know the veg oil has a higher viscosity and glycerin in it. why would i "need an older w123/126"?


You need an engine with indirect injection. All recent MB and VW diesels are direct injection -- so you should focus on the older MB models with the older injection systems.

 

[bullwinkle]

The TRUE danger of running vegetable oil, either new or used, is the glycerine content in the vegetable oil WILL eventually cause stuck piston rings-if you look into the biodiesel websites, you will find instructions on processing your own bio using methanol & either lye or potash to get the glycerine out. If I had more room like an old barn or well-ventilated building to set up the baby chemical plant I'd be doing it already! Personally I would be leery of any diesel vehicle that already has a 2-tank system-there are NO guarantees that the IP or rings are already damaged by unknown fuel!

 

[bullwinkle]

I would also agree that engines using the INLINE Bosch injection pumps such as the older MBs, '94-around '98 P-pump Cummins/Dodges, and tractors are the best candidates for biodiesel. The Stanadyne & other ROTARY IPs can be pretty much destroyed by ONE shot of water in the fuel-making bio risky-not impossible-but extra water separators/filters would be in order. Anybody who's ever had to pay to replace injectors in a CR or HEUI system knows what damage questionable fuel is capable of-buyer beware!

 

[Tornado Red]

Originally Posted By: bullwinkle
Personally I would be leery of any diesel vehicle that already has a 2-tank system-there are NO guarantees that the IP or rings are already damaged by unknown fuel!


That is absolutely true. The only thing worse than converting a perfectly good diesel engine so it will run on veggie oil, would be buying a car which someone else has already converted.

This is because the cost of replacing an engine in one of these older MB or VW cars is likely to be greater than the value of the car. So once you destroy the engine, you might as well just tow it to the salvage yard.

 

[jmaster]

is the inline 5 in the 300d direct or indirect injection?

i'll have to look into the negative effects of veg oil/glycerin. i researched every aspect of running bio and veg, everything from water washing to the freezing points, but i haven't looked into the bad after effects of the glcerin.

i am prepared to make bio diesel as well. thats what i planned on doing because it would be more simple than maintaining the 2nd tank system on the car dealing with heating ect. but heck if it lasts 50,000 miles on veg, thats 10 years of driving for me. and if i buy the car for $500 that is very little capital cost.

 

[Tornado Red]

Originally Posted By: jmaster
is the inline 5 in the 300d direct or indirect injection?

i'll have to look into the negative effects of veg oil/glycerin. i researched every aspect of running bio and veg, everything from water washing to the freezing points, but i haven't looked into the bad after effects of the glcerin.

i am prepared to make bio diesel as well. thats what i planned on doing because it would be more simple than maintaining the 2nd tank system on the car dealing with heating ect. but heck if it lasts 50,000 miles on veg, thats 10 years of driving for me. and if i buy the car for $500 that is very little capital cost.


If that is all you drive or plan to drive, then why even bother with veggie oil or home-made biodiesel, Assuming 25-30 mpg, a diesel MB will only consume 1666-2000 gallons over that time frame, or 166-200 gallons per year.... roughly one tank of fuel per month.

I do not see how you can possibly recoup your initial investment -- I suppose you can install a second tank for $1000 or so, if you do a fabricate a lot of the parts yourself and do all the labor of installation. I also think you are minimizing the hassle and expense and the damage that veggie oil can do to an engine. If uncombusted veggie oil gets down into the crankcase, you would have to tear the engine down entirely to clean it our.

 

[jmaster]

i know right now i am spending $100 a month on fuel, $1200 a year. i would cover the cost of the car and tank in a year or less.

and i know when gas and diesel rise to $9 a gallon i won't be buying any.

as far as glycerin damaging everything, i have heard nothing. i'm not calling you on anything but have you seen any cases of this happening? how could there be such a following and so many people with conversions if they ruin the engine no matter what?

 

[bullwinkle]

A 300D will be IDI, they didn't become DI until the "E" class days-trust me, do an online search, one of the MB forums I belong to is Peachparts (the former mercedesshop)-you'll see what I mean on the piston ring trouble! Another problem with the old turbo 300D motors is the tendency of the cylinder sleeves to get egg-shaped, causing blowby & low compression (which my '82 unfortunately has)-requiring sleeve replacement, new rings, and BIG MONEY new pistons!! Some of the newer W126 six cylinders are called "rod benders" because of weak connecting rods, combined with questionable aluminum cylinder head castings, cause bottom end problems!

 

[Oldwolf]

My 93 MB 300D has the 5 cylinder (OM602) engine. The injectors are in pre-chambers. I've considered this direct injection, correct?

 

[Tornado Red]

Originally Posted By: Oldwolf
My 93 MB 300D has the 5 cylinder (OM602) engine. The injectors are in pre-chambers. I've considered this direct injection, correct?


Nope, it sounds like you have an indirect injection engine (IDI). It is safer for veggie oil conversion -- not exactly safe, mind you, only relatively safer than direct injection.

 

[bullwinkle]

That is also the Bosch inline IP in the '93, very similar to the older 3.0 liter 5 cylinder (IMHO other than better power & MPGs due to the aluminum head & smaller displacement!).

 

[Gito]

If you get a 300 mb be sure to switch out the old injection nozzles and replace them with Monarch nozzles. You will use the old bosch injector but will replace the injection nozzle only. Diesel Giant sells them.

 

[jmaster]

some other good nozzles are bosio. they are made in italy too.