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Old 02-21-2004, 11:11 PM
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Location: rio grande valley texas
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Is this normal for a mercedes diesel?

Hello I am a new mercedes diesel owner, although I am not new to diesels. I just bought a 1986 300 sdl and the takeoff is extremely slow, I literally put the pedal to the floor and the car just gradually begins to build steam up until I get into the higher gears and then she just bolts. It feels as if I am pulling a trailer or something. I have had early volvo diesels and current vw and ford diesels and the takeoff performance is considerable faster. Any help on this matter is greatly appreciated

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Old 02-21-2004, 11:43 PM
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Join Date: Feb 2004
Location: Double Oak, Texas
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Welcome. I recently picked up my 84 300SD and do not find it that slow off the line. Just yesterday I got all over a Cat powered bulldozer from a red light. It was close for a few minutes but he finallly reached his top speed and I pulled away. Well, serioulsy, these do not have great 0-30 times, do they.

Actually, after fuel filter and air filter changes, and driving the car more, the accel. from stop keeps getting better. I have another week off before I start new job so I'll adjust valves maybe on Tuesday. The car had been sitting for some time before I bought it and I am noticing that the more I drive, the smoother the accel. and the tranny shifts get. It takes some getting used to the feel of the accel. pedal compared to my other vehicle. But a good strong push on the MB pedal gets the car moving out pretty well.
1984 300SD 326,997 miles and counting . . . No wait, my odometer is still dead

Last edited by RockinWagin; 02-22-2004 at 05:42 PM.
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Old 02-21-2004, 11:52 PM
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Join Date: Jul 2001
Location: Chapel Hill, NC
Posts: 321
Hello and congrats on getting a Benz.
Your SDL should not un-impress you at all. I would do extensive searches here and you'll come up with a lot of stuff about your slow accel. You will be happy you did as your car, in my opinion, is definitely not slow like you describe when it's functioning properly. Many would describe at as pretty fast, even if it were a gasser.
Have fun, Adam
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Old 02-22-2004, 03:26 AM
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Join Date: Jan 2001
Location: Wilmington, NC
Posts: 334
I had same problem with my 83D. Took it to my trusty trans man and he fixed it. Said it was a "low gear piston". To this day I have now idea if such a part exists, but he fixed it.. circa $150, I think.
Nello Tare

1982 300D (266,001 mi.) looking and running great

Previously owned:
1976 450 SLC
1983 300D
1976 300D
1982 Jaguar XJ6 (loved, but gone)
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Old 02-22-2004, 04:58 AM
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Join Date: Mar 2002
Location: Pacifica (SF Bay Area), CA
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Have you checked the throttle linkage to make sure you're really getting full throttle?

On my 300D, I found a while back that there was still 1/8" of arm travel at the injector pump with the pedal to the floor. I adjusted the linkage, and it was like a completely new car. I couldn't believe it...

Also, at least on the OM617, there's a plastic hose that goes between the intake manifold and the ALDA on the injector pump. This tells the ALDA how much boost pressure there is, and the ALDA then has the injector pump add fuel accordingly. If this plastic hose is gunked up (common, unfortunately, courtesy of the EGR valve), you can have power loss issues...also, on this line there's a 3-way electric valve, so that if a sensor on the intake manifold senses too much boost, the boost signal going to the pump is instead vented to thin air.

I don't know how much either of these will help with an OM603, but I hope it at least gives you some ideas on things to check. Good luck!
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Old 02-22-2004, 09:28 AM
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Location: eastern ND
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Wanna race (at least until you get things tuned up)? I can beat kids on their bicycles, unless it's downhill.

The Warden is getting you started. After lubing the throttle linkages, I'd adjust the valves, check the air and fuel filters, then do the vacuum line cleanout that The Warden suggests.
daBenz - 1970 220D
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Old 02-22-2004, 11:12 AM
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For the record......

My '87 300SDL is, is, is darn fast. Not an precise statment, but, I'm sure you get the point. Just follow The Warden's good advice.
Paul 1987 300 SDL; 2000 ML; '69 MGB; '68 VW Fastback
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Old 02-22-2004, 11:45 AM
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Location: rio grande valley texas
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thanks for the great info

I just want to say thanks to all who replied to my post, I have never seen a finer group of helpful and informed people. I will take everyones advice and see if I can get my "baby" up to speed.
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Old 02-22-2004, 02:00 PM
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Join Date: Oct 2002
Location: Bay Area No Calif.
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Some advise, such as adjusting valves is not applicable to this car. The OM603 engine uses hydraulic lifters. I have not seen the need to adjust linkage on this engine either.
Any comparison the W123 or pre-86 W126 diesels is unfair, the SDL should get up and boogey, for a diesel it is a class performer in diesels made up its time, although its on a relatively heavy chassis it is not sluggish when everything is proper. Just be certain the engine never gets overheated, search for info on this using the search feature and you will see the reasons why this is important.

There is however a possibility that your car still has the trap oxidizer. The factory had a recall and this was replaced and I believe eventually they bypassed it and installed a cat converter. The symptoms of a plugged trap is a very sluggish engine.
Check out what is (or isn't) in place in the exhaust line from the turbo outlet to the muffler, and let us know what you have!
Last thing to suspect it possible turbo bearing failure, not a major problem but not trivial either (BTDT).
'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

Last edited by dieseldiehard; 02-22-2004 at 02:06 PM.
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Old 02-22-2004, 02:25 PM
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Location: rio grande valley texas
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I just checked the exhaust line and that on end of the turbo leading towards the exhaust there is an accordian shaped part it is sandwiched between what appears to be braces of some sort. I wish I could be more technical. The problem is encountered only on initial acceleration from a standstill, and to be quite honest I doubt I would beat a cat bulldozer off the line but after about 25 feet I will pass him. The car currently has about 217,000 miles on it and on initial purchase I drove it 400 miles home averaging about 70 to 80 miles an hour with no problems. I even averaged a cool 30 MPG. As mentioned the car is great past 40 miles per hour it is only during initial acceleration where everyone and their grandma on walkers get by me.
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Old 02-22-2004, 05:20 PM
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I had the same problem when i picked up my mercedes in Texas for the drive home to California. I remember one hairy situation in particular; coming out of a fuel stop in west Texas and getting honked at from all angles as i CREEP across 3 lanes of traffic...I thought I had room After I changed both fuel filters (which I brought on the plane with me in anticipation of such a problem) in El Paso, the Benz ran fine. After getting home a day and a half later to San Jose, I checked and adjusted the linkage, and cleaned the ALDA line. After that, it ran great and has been since.

BTW, A prize goes to whoever notices whats different about my sig first!!
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Old 02-23-2004, 08:43 AM
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Location: rio grande valley texas
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i repaired a broken hose that ran from the intake manifold to the firewall and back to the engine, it seems to have improved the acceleration times a bit. The hose is very dark as if dirty, it does allow air to flow through.
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Old 02-23-2004, 09:12 AM
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Part of your problem is probably turbo spool-up. These turbo engines need to be above 2000 or so RPM to begin making their power. If not, they'll go, but they will be slow. It may be your typical driving habits (if youre very light footed) coming back to get you.

Also, check that your transmission isnt shifting too early. Do a search on 'bowden cable' to see how to change your shift points. If you screw it out, the trans will hold gears longer. I have a problem where my shiftpoints are too close together, and sometimes are really low, so Ill be in 4th gear by 20-25 mph. If Im not hard on the throttle the car will be a slug at that point, especially if going up an onramp.

But my car has plenty of power under 30 mph, so long as Im not expecting v-8 performance, and keep the right gear.

Current Diesels:
1981 240D (73K)
1982 300CD (162k)
1991 350SD (113k)
1996 Dodge Ram CTD (438k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)
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Old 02-23-2004, 10:03 AM
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Location: Albuquerque, NM & Lakeside, AZ
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Based on your last post and others, I would check your boost line. It runs from the intake manifold to a valve on the firewall to the IP. On the IP it transmits boost pressure to a device called the ALDA. The ALDA will increase fuel delivery as boost increases. The valve on the firewall is to stop line pressure if an over-boost situation (i.e. stop you from melting your engine). If your EGR valve has not been blocked off (which most likely it probably hasn't) then exhaust gases entering the intake manifold can plug up this system. Plugged system will really effect preformance. Clean the lines and clean/replace the valve. You can check it by by-passing it for the test. The item that may need attention is the ALDA itself. Most are set too lean at the factory. If your has already been messed with the foil seal at the top may have already been broken. The ALDA should be adjusted so that in daylight you just begin to get light smoke at full acceleration and engine RPMs are around 4K+. Now this is only true with a clean engine so a few full power accelerations ("Italian" tune-ups)are in order before you adjust. ALDA adjustment is not best performed by a newbie on the OM603X as it is covered by the intake manifold. It can be done with the manfold inplace but not if the foil seal hasn't been broken. I managed to do it without removing the manifold using an offset screwdriver and small box-in wrench. CCW turns the fuel delivery up. Only turn about 1/2 rotation between adjustments. It has a locking nut with a screw adjustment. Do a search on ALDA adjustment and you should find a thread that Dave M. did with pictures. He is one of the OM603 experts on this forum. Hope this helps
D. Blake
86 300SDL 340K (for sale)
83 300SD 205K (gone)
06 Chevy K3500 LBZ CCLB 50K
94 Chevy K2500 6.5L TD 250K (gone)

Last edited by D.Blake; 02-23-2004 at 10:09 AM.
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Old 02-23-2004, 06:45 PM
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Location: Double Oak, Texas
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Originally posted by D.Blake
Based on your last post and others, I would check your boost line. ...
D.Blake, that was a very good post. Thanks. The more I drive mine, the more I get used to it. I haven't had a diesel since 1986 (when I sold my 82 Nissan diesel pick-up).

1984 300SD 326,997 miles and counting . . . No wait, my odometer is still dead
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