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  #1  
Old 07-03-2002, 02:17 PM
Don Atienza
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Unhappy Where's the 'diesel' climbing power?

Hi guys!

I had this rather embarrasing experience just the other day:

My friends and I decided to go to the movies in this new mall. The three of us (we're all light-built, you'll see the relevance of this info later) rode my old-reliable 1976 w123-200D. As with all malls here in our area, this one had a multi-level parking space. As I entered and had to stop to get the parking ticket, I was a bit surprised to see that the entrance had an unusually steep incline (though Im not sure how or what 'grade' it was). And so, I gunned the engine (my car has a 4-speed manual tranny) in preparation for the climb. As I released the clutch, the car moved forward but as I approaced the steep incline, the revs dropped and I had to step on the clutch and stop because the engine almost died. I double checked and made sure that I was on first gear. I asked the parking attendant to stop the cars at the back because I might have to back off. Still stationary on the inclined area, I again tried but the same thing happened. What I did then was to back off to level ground and then accelerated towards the incline. Again, the car failed. And so I tried a few more times and took a longer starting point and finally, I did it. The incline was just about 20 meters. Im sure that the problem is not on MY driving. What added insult to injury was that the woman behind my car in the small Toyota seemed to climb the same incline almost effortlessly. I could just read the thoughts of that parking attendant, and those of my friends, since I would always praise Mercedes, or in those instances my car in particular, for all its abilities. Aren't these models supposed to have good climbing power? My engine is ok, since we just rebuilt it about 5months ago. At that time, we also had all the fluids and filters replaced (though this car has the mesh-type air cleaner; just cleaned that thoroughly), and about 2 months ago I had the clutch-plate replaced as well. The car has been 'broken-in' and has been adjusted to specs since then. Well now, I have to ask... what's wrong with it? Is it fuel delivery? What I haven't done is to have the injection pump checked/replaced. But the car can still run above 100kph though being the normally-aspirated diesel powered car that it is, it takes a looooong time to get there. Neither does it have the overtaking power of gas-fed cars, but its acceptable nevertheless. It does emit the normal amount of smoke you would expect from a diesel car (nothing obstrusive even at high engine speed). Im not as happy with its mileage, though (6-9kms/liter stop-and-go traffic, 9-11kms/liter on the highway. Is this ok? I was told it should be higher since it only has a 2-liter diesel engine.). One last thing, I think we installed a 1979 w123-300D (non-turbo, auto trans) differential on this car (that's another long story but its done so...) which does not seem to have a marked effect anyways, until now. Im not sure but I think it has a different ratio. Forgive my verbosity but I just had to give the background. Please help me reclaim my bragging rights for this car . Thanks in advance!

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  #2  
Old 07-03-2002, 02:52 PM
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Don, I'm way new to MB's so I can't quote any specific numbers but I'm not new to cars.
First thing I would do is find out what your stock axle gearing was in the axle you removed and then find out what your swapped in axle has for a ratio. If for example(again I'm not familiar with MB numbers) if the old ratio was say 3.90:1 and the newer one is 3.30:1, in a low HP motor like the 200D that can make a world of difference in 1st gear starting on an incline. You wouldn't notice it too much on a flat staright road at hwy speed though. If you've significantly raised(lowered numerically) your axle ratio you may have to just rev the dog ***** out of it starting on an incline. I'm not saying that's your prob but since you did mention the rear axle has been swapped to an unknown ratio that's where "I" would start anyway. Good luck...hope it's just something easy like a clogged air filter.
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  #3  
Old 07-03-2002, 03:56 PM
Holson Adi's Avatar
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Yeah I'm quite inclined to believe that it is indeed the rear end.
The 200D has 50hp I think and the 300D has 80 or 85hp those 30hp might mean that they fit the 300D with a taller rear end to give the car about the same amount of acceleration but a higher top speed / lower engine revs/min at cruising speed.

Otherwise I guess you just have to rev the crap out of it on an incline and drop the clutch. I have a 230E manual (M102) - W124 and that thing isn't the best hill climber either..

The 300D Turbo is quite good at it though...
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  #4  
Old 07-03-2002, 04:34 PM
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Have you considered getting new, really really skinny friends ?

Have you considered getting some bigger friends and train them to jump out and push in those types of situations ?

I would suggest you check your fuel filters, start of fuel delivery and chain stretch. Five months is enough time to grow algae or get water in the tank which might move to another spot when at a real incline... but since you did not get the turbo rear end I think you should have enough power to climb that hill in low if your engine is in normal shape.
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  #5  
Old 07-03-2002, 04:59 PM
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My family had a 67 200D, not fast but first gear was a stump puller. I agree with investigating the rear axle ratio. I'll bet it's too low (high geared) as it's common in various makes of autos to have higher geared rears especially if the engines are larger.

Frank.
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  #6  
Old 07-03-2002, 06:04 PM
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Could not find a reference for the rear axle ratios for the cars, but I did see a quote from MB for the mileage in the city for a W123 200D, and it is 9.5 liters per 100 km, or a bit better than you are getting. So, it may be that your axle ratio has the engine working too hard to get the car moving. Chances are it will adversely affect the life of the clutch too. Good luck and sorry I could not get a little more definitive. Jim
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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)
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  #7  
Old 07-04-2002, 11:51 AM
Don Atienza
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Thanks for the replies! My dad worked for MB before and he has this little old blue book of various numerical values for old MBs. I'll look for the specific values of the rear axle (which nonetheless for an amateur like me wouldn't amount to much really) and hopefully we can probably discuss the ramifications of the change I made. For the meantime, I'll just avoid that place... or I can bring some strong pushers along!
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  #8  
Old 07-04-2002, 12:39 PM
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Skinny Friends

Laughed myself silly at leathermang's "skinny friends". From the sound of the problem, he must have the turbo rearend in his 200D. That's 3.07, the normal 240D is 3.46 which works very well for them. I wouldn't not be surprised if the 200d was an higher Number, making it a lower rearend ratio than the 240D.

If he doesn't want to crawl under the car and check, all he has to do is check his speed in one of those speedometer areas along the highway, that's if the car will get up to 60MPH. He'll undoubtedly find that his speedo is way off. The speedometer gage is setup for a specific rearend ratio, so when you change one you must change the other.

His, obvious solution other than fewer and skinnier friends is to go back to the correct rearend ratio.

Ben
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  #9  
Old 07-04-2002, 02:23 PM
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Since we know he has 'some' relatively skinny friends I think it would be easier to have one of them reach under the driveshaft and make a mark.. and make a mark on a wheel where it touches the pavement... then roll the car forward until the driveshaft has made exactly one rotation... and count and measure the number of rotations the wheel has made... I actually recommend the set of heavier friends that get out and push.... I used to be able to push start my Karman Ghia on a flat parking lot by myself and jump in to pop the clutch....REally skinny friends seldom are any help lifting objects from what I have experienced....

Last edited by leathermang; 07-04-2002 at 04:46 PM.
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  #10  
Old 07-04-2002, 03:04 PM
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I think the 240 has a lower rear end than the 300 non-turbo based on the shift marks on the speedo and the top speed -- top speed is about 85 on the 240 and 95 on the 300, indicating a different rear end.

Diesels are notriously low on torgue at low engine rpm. At least you didn't stall it and get it running backwards!

Find the correct rear end and swap it out. Shouldn't stall on a steep ramp like that. The manual tranny doesn't help, either, no slip.

Peter
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1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
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  #11  
Old 07-04-2002, 04:18 PM
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The shift points might be affected by the ratios of the individual gears in the manual trans...

OK, found my 123 FSM's and this is what I think I read in the charts...

the 123.123 (240d) with the 616.912 engine has the 3.69 rear axle ratio. (PSFred was correct)

For what it is worth it also shows something called 'gradability' with the manual transmission for this combo...

1st gear (slip limit)%(1 in) 35 (2.86)
2nd gear ditto 19 (5.86)
3rd gear ditto 10.5 (9.52)
4th gear ditto 6.5 (15.38)

123.130 (300D) rear axle ratio is 3.46 autotrans

1st gear ditto 41 (2.44)
2nd ditto 37 (2.70)
3rd ditto 15 (6.67)
4th ditto 7.5(13.33)

300 turbos (all) rear axle ratio is 3.07

What these charts actually mean in English I can not explain. Help,somebody?
I typed this neatly as a chart but it posted squished together....

Last edited by leathermang; 07-04-2002 at 04:56 PM.
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  #12  
Old 07-04-2002, 05:15 PM
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Greg,

Germans list the grade of the hill as a percentage of the ratio of rise over run. Thus a 10% grade is rising 1 meter in a run of 10 meters. Which is pretty steep in real life.

You inspired me to get out my owner's manual for the 300D I imported and sold. It was in German and I got the owner an English version.

Under the topic of "Steigvermoegen," which translates into "climbing capability" the cars are listed as having the following grade climbing capabilities:

200D:
1st gear: 34% with either manual transmission, 36% with the auto box but with a note saying you have to have a "grippy" surface to achieve this.

240D:
1st gear: 41% with either manual transmission, 42% with the auto box but with the same note about grippy surfaces.

300D (non-turbo):
1st gear in all transmissions is good for 41%, again with that grippy surface.

Top speed in first gear for each car is:

200D: 37 km/hr
240D: 39 km/hr
300D: 42 km/hr

These are all with the manual transmission. They all are limited to 5,300 rpm, and they all come standard with 175 SR-14 tires.

This would indicate a final drive ratio difference of 13.5% in the overdrive direction for the 200D in first gear, which, considering it has 32% less torque than a 300D, is a serious disadvantage for the little bugger. It would seem you need to be running near 2400 rpm (the torque peak for all these engines per the manual) for the 200D to make the grade.

But, that park garage was not a 30% plus grade ramp. It might have been around 10%, but I cannot imagine it was much more as if it ever got wet stopping from any speed would be impossible. So, I think there is something else out of whack with Don Atienza's car. The right rear end ratio will help a lot, but it seems there is something else amiss unless that ramp was really steep. In that case it might not be practical to hit it at 15 mph in first gear, especially with some skinny or not folks in it.

By the way the grade capability figures were with 2 people in the car. Another couple of skinny people might actually make a difference of a few degrees, but I am sure the ramp was not a 34% grade.

Well, hope that helps a little, Jim
__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)
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  #13  
Old 07-04-2002, 07:28 PM
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Thanks Jim, I agree that with an engine in reasonable shape it should have made it up that grade.
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  #14  
Old 07-04-2002, 08:02 PM
Don Atienza
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Hi!

Found the book, and here are the values:

Rear Axle*
123.120(200D) 3.92 number of teeth: 47:12
123.130(300D) 3.46 number of teeth: 45:13

*standard version

Looking at these values, im not certain if it will bring about too much of an adverse effect. Will it? The diffference seem negligible. Are there any advantages to holding on to the present rear axle or should I just re-install the original?

From the fuel delivery point of view, what adjustment can I do so as to squeeze a little bit more from the engine? By the way, I did observe that the speedo might not be registering the right speed (and distance at that).

Thanks a lot for the explanation re the climbing ability, grade and stuff. It makes the discussion very educational (now I just have to find a 'Car Mechanics for Beginners' book to help me keep up. Any suggestions?).

Nevertheless, I think the car will benefit more if I stick with the skinny friends!:p
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  #15  
Old 07-04-2002, 09:01 PM
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yes,, the suggestion is to check and see why your engine may not be giving you the power it should be....

But you need to determine if you might have accidentally gotten a turbo rear axle under your car... which would change you basically from 4 to 1 to 3 to 1... and that really could make a big difference...

You can do that by marking the driveshaft and the tire as I described above...

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