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+--- Thread: New to Mercedes Diesels (/showthread.php?tid=1690)
New to Mercedes Diesels - cbryan0222 - 09-02-2010
About two months ago i bought my first Mercedes diesel car. It was a 79 300d non turbo car and since then i bought an 82 300d turbo car. It has 172000 original miles and is a really clean car inside and out. I'm not very familiar with any mods on any diesel. i am only 20 years old. My 82 doesnt seem as it runs the way i thought it should. its a little doggish. not quite as bad as my non turbo car but not where i thought it should be. I'm sure it has sat many years without being drove. i was curious as to any maintanance tips to help it run better. I've replaced all of the filters but thats about it. Any ideas would be greatly appreciated.
RE: New to Mercedes Diesels - willbhere4u - 09-02-2010
check and make sure your fuel tank screen is not blocked with junk!
RE: New to Mercedes Diesels - cbryan0222 - 09-02-2010
Thanks. Where is the fuel tank screen? I wasnt aware they even had one.
RE: New to Mercedes Diesels - Captain America - 09-02-2010
(09-02-2010, 09:26 PM)cbryan0222 Thanks. Where is the fuel tank screen? I wasnt aware they even had one.
Well its in the tank haha. Mine is jammed with shit.
-adjust the valves
-diesel purge
-EGR block off
-clean ALDA line that comes off of the back of the intake manifold
-Boost controller set to 12psi
RE: New to Mercedes Diesels - JB3 - 09-03-2010
(09-02-2010, 09:26 PM)cbryan0222 Thanks. Where is the fuel tank screen? I wasnt aware they even had one.
access is underneath the car above the passenger side rear axle. Basically a canister that unscrews and pulls out from there, drain or run the tank mostly empty first though, otherwise a big mess awaits!
For the interim to see if thats the full problem, you can swap supply and return in the engine bay and see how it changes performance. Return line extends to the bottom or very low in the fuel tank like supply, and the vehicle can draw fuel from that tube as well.
The other major thing like Captain says is to adjust the valves. NO ONE does this regularly except enthusiasts. I think the spec is something like every 10 thousand miles, but I have owned several cars where its hasn't been done in 30 years! That alone can make an enormous difference in power and performance.
RE: New to Mercedes Diesels - Captain America - 09-03-2010
There was a HUGE difference when I swapped my feed and return lines. I've been running off the return for a couple weeks now waiting for the tank screen to come in. I will be cleaning the tank out this weekend...
RE: New to Mercedes Diesels - ForcedInduction - 09-03-2010
I've always been running off the return line. I'd rather change the primary filter ten times than have to drain the tank once.
RE: New to Mercedes Diesels - Biohazard - 09-03-2010
It is a messy job, but I've done it twice. Luckily, it wasn't as messy the second time around!
I pulled it out the second time a year after putting in the new one just to be sure is was still clean (it was).[attachment=3506]
That effin filter cost me more time, money and headache than I'm freely willing to admit to right now. LOL If your car is dying or really low on power, and are getting air bubbles coming into the primary fuel filter, your in tank strainer could be borked. <---- Highly Technical Term
I really, reeeaaallly wish I'd have thought about swapping the feed/return lines when my car died in Texas, Kansas, Colorado, Utah and Washington. Meh. The previous owner may or may not have spent a small fortune on possibly un-needed repairs to this car due to a $20 dollar filter... FTW!!! 
RE: New to Mercedes Diesels - cbryan0222 - 09-03-2010
Awesome guys thanks for all of your help. I just bought a parts car that the motor is supposed to be good in and i cant get much fuel to the primary filter due to air bubbles. That'll be a big help in getting it to run.
I also believe that i need to adjust the valves on my nicer car due to the fact i doubt its been done in a very long time. (If Ever)
RE: New to Mercedes Diesels - JB3 - 09-03-2010
I did the same as forced, with the same rationale. Never had a problem at all with it, although I think both of us have 123 chassis, so perhaps biohazards 126 might not have exactly the same tank design? He'd have to verify or just cut the screens out of the screw in filter.
You still have two other filters on the fuel system without that screen getting in the way.
RE: New to Mercedes Diesels - Biohazard - 09-04-2010
(09-03-2010, 11:41 PM)dropnosky I did the same as forced, with the same rationale. Never had a problem at all with it, although I think both of us have 123 chassis, so perhaps biohazards 126 might not have exactly the same tank design? He'd have to verify or just cut the screens out of the screw in filter.
You still have two other filters on the fuel system without that screen getting in the way.
The W123 and W126 take the same fuel tank strainer. I just looked up the part numbers, they match. It sits just over the passenger side inner axle boot. When I did it the second time, I ran the car till the fuel gauge was on the empty mark then drained the rest out of the tank from the return line. Even after that, there is going to be a small mess so be prepared.
If you do the tank strainer, get the new o-ring and hose too if yours is at all old looking.I'd recommend doing like the others said and swap the feed/return lines first to see if that helps, then you know the tank strainer is plugged. Doing the primary (clear filter) and secondary (spin on) filters is also a great idea along with a valve adjustment. A little bit of maintenance goes a long ways with these engines. Hope that helps!
RE: New to Mercedes Diesels - cbryan0222 - 09-04-2010
Ya Thanks a lot guys. I'm still pretty new to these cars and i'm learning more and more everyday. The more i learn the more i love Mercedes.