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  #1  
Old 07-11-2001, 04:25 AM
David C Klasse's Avatar
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You can check out this post to see how the trip was...
http://www.peachparts.com/shopforum/showthread.php?postid=103868#post103868

But I have a few questions on the performance of my C280.
First of all, I do know that power is lost with an increased load, less air density, uphill driving, A/C etc.
Well I had two other people in my car, and a lot of gear, most of it blankets though (I packed the heavy stuff in the E430!)

Well as usualy, temp climbed to about 110 going up the hill, and I swear it felt like I had lost 50 horses. I probably had.... anyway, the outside temperature was about 70 or so, and the trip ranged from 1,000 feet to 7,000 feet high. Well I turned the A/C off to preserve power, gas mileage, and to lower the engine temp... nothing! It still climbed high. So I then turned on the heat full blast, closed center and passenger vents, and aimed the driver's side vent out the window to see if I could lower the engine temp that way... nope, still climbed to 110 +. I was now getting a little concerned, even ext. temps had dropped to 60 or so. Now I know this is all still OK for a Mercedes, but I have a 80/20 mixture of water to MB coolant (thanks Jim), and 2 bottles of Waterwetter (which I know don't always reduce coolant temp, but dissipate hot spots) that were all put in about 3 months ago, so it's fresh. And I everything else is in working order, etc. Well Justins Mercedes showed no increase in engine temperature... why do new MB's hold their temp stable, but once a few years old, start to climb? Is there any reason?

I also noticed VERY rough shifts up the hill also. Why is this? Hot AT fluid? I kept it in 3rd a lot of the time though. But flooring it to pass and keep up with Justin was rough and very slow. (I swear I wanted to run every Minivan on that road off the side of the hill, grrr, I understand, John Shellenberg!)

And one more thing, during our time up there, I went through a few large puddles, and then ran my battery dead. Well I jumped it, and had it started for about 20 minutes idling, then went on a 30 minute drive (through deep water), when I got back, I turned off the car, and tried to restart, and it didn't start... I was thinking that maybe water got into the alternator or something!? So we jumped it again and I let it run for about 1/2 an hour, tried to restart, and it still didn't start. I then thought screw it, I'll deal with it when we leave in the morning. So in the morning, I jumped the car, it started and I took the 2 hour drive home. When I stopped the car, it again started right up the way it should. Why do you think this is? Do you think that it just needed a really good charging? Or did the moisture/water somehow prevent the batter from charging?

Thanks for the help guys.
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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)
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  #2  
Old 07-11-2001, 09:22 AM
pfphipps
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I live in Albuquerque at an elevation of about 6000 ft. The temperatures you talk about are about normal for my 93 300E2.8. I have a 50/50 mixture of MB antifreeze, nothing else, but the cooling systems is super clean with no gunk in it. My temps might be 5 degrees cooler but how well are the temp gauges calibrated anyway? I don't turn off the air conditioner or do anything else to try to get the temperature down. On 90 degree days with the a/c going, I always thought it was interesting when I climb the big hill for the last mile home to my house that the temperature actually starts going down as I reach my driveway. I guess the thermostat is wide open and all the fans are going full tilt. I have had the car since new and there are no temp changes with age that I can tell. I have a couple of other newer MBs and they act about the same.

I drove to Santa Fe last Friday. Outside temperature was about 95 and I had four people in the car. At 75 to 80 mph, I noticed it actually ran a little cooler even on the upgrades than around town.

As far as the power loss, 95% of my miles have been above 5000 ft so I guess I do not notice or have nothing to compare with.
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  #3  
Old 07-11-2001, 11:46 AM
G-Benz's Avatar
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Join Date: Apr 2001
Location: Dallas/Fort-Worth
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Can't comment on MB performance at high altitudes...left all of them at home when I did a 6-month contract in Colorado Springs. Decided to buy a cheap car for driving to work and around town, then sell it when I move back to Texas.

Bought an 86 Chrysler Conquest turbo for $3K. Decided I liked it, so I got it repainted, redecaled, rims polished, valve cover polished, etc. etc.

Anyway, even with the turbo, it was anemic around town. Never got the boost gauge past 0 psi. When I finished the contract, I drove it back to Texas. The car literally screamed when I got to the lower altitudes...boost gauge shot up to 7 psi!

Funny thing is the engine temp was always normal, whether in Colorado or Texas...
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  #4  
Old 07-11-2001, 02:22 PM
Ali Al-Chalabi's Avatar
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Join Date: Nov 2000
Location: Knoxville, TN
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Well, from my experience with the C280, it seems to be a warmer running car than a lot of others.

A long climb like that puts a lot of stress on the engine and can start to overload the cooling system. The engine is fully insulated on all four sides and there is not a tremendous amount of space under the hood, which makes it harder to pull air through the radiator and dissipate heat, the radiator is also not exactly the largest thing in the world.

As far as the transmission, it could overheat, I would check the fluid, and if it is burnt, replace it soon. I always thought a transmission temp gauge would be nice, unless there is some way to get a tranny temp reading from the climate control. I know that on the 722.6 tranny, the transmission temp needs to be monitored through an internal temp probe in the tranny to get an exact reading. Does anyone know if this is this a value that can be pulled out of the climate control.
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  #5  
Old 07-11-2001, 03:07 PM
David C Klasse's Avatar
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Sorry, I forgot to mention that the trans fluid and filter had been changed about 4,000 miles ago, so I ruled that out as a reason for the rough shifting.
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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)
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  #6  
Old 07-11-2001, 05:53 PM
Ali Al-Chalabi's Avatar
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Join Date: Nov 2000
Location: Knoxville, TN
Posts: 1,837
If the transmission was severely overheated, then the fluid could be due for another change regardless of the mileage of it.

The rate of oxidation for transmission fluid goes up exponentially as the temp of the fluid rises.

At 175F, the life of tranny fluid is about 100,000 miles.

At 250F, life would be under 10,000 miles

At 300F life would be about 1,000 miles or less, but that is some severe overheating.

I would check to see if the fluid is burned, it could be if it severely overheated.
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  #7  
Old 07-11-2001, 06:10 PM
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Location: Plano, TX
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My memory's foggy on this topic, but I think you'll see about 25% power loss at 7,000ft. Your guess of 50 missing HP is probably on the mark!

As for why the trans shifts harder, that's easy. Because of the reduced engine output you are using much larger throttle openings to generate the kind of acceleration you are accustomed to. The trans shifts more firmly the more the throttle is opened, hence the very firm shifts. No magic there.
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  #8  
Old 07-11-2001, 06:43 PM
David C Klasse's Avatar
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Location: Mission Hills in the City of San Diego
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Ali,
I see what you are saying, I will check the trans fluid.

JHcuyhn,
Do you mean that when I floor it under normal conditions that the trans should shift that roughly? If it is, then it doesn't. What I mean is that at regular altitude, I always have smooth, precise shifts, unless the engine is cold of course.
I have never experienced this kind of shift unless the engine has been cold, in which I don't drive the engine hard.
Thanks guys, anything else?
__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)
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  #9  
Old 07-12-2001, 11:07 AM
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Join Date: Jun 2000
Location: Plano, TX
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Hmmm... Well, so much for that theory. I would expect the car to perform/feel different at 7,000ft in elevation than at sea level.

The transmission shift firmness is reasonably well calibrated to the engine output. Hence it all feels well and good when driving around town. Take the car to elevation and the engine produces much less power at the same RPM. Yet the trans shifts about the same. Different feel - it's as if the engine/transmission tuning has been tweaked.

This may or may not explain what you experienced.

I don't think your usage will have overheated or stressed the transmission in any way. Heck, it pretty much qualifies as normal usage. Ever seen the way Europeans drive their cars? Ever seen the roads in the Alps or Pyrenees?

All my older Benzs tended to shift more softly as the transmission got hotter. My '87 wagon shifts like butter after a good highway run in our 102F Texas heat.

If you're really concerned, have the transmission serviced and use a fully synthetic ATF. I have Mobil 1 in my wagon. Mostly I notice how smoothly it shifts right out of the garage on cold winter mornings. On the other side of the equation, it's almost impossible to hurt synthetic ATF through overheating - it's much more robust at high temperatures than old dinosaurs.
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  #10  
Old 07-12-2001, 12:21 PM
David C Klasse's Avatar
CheFrac is Back!
 
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Location: Mission Hills in the City of San Diego
Posts: 2,352
I am not really worried, and I am pretty convinced that my transmission is just fine. I was just curious why it did this under load, because I've never experienced that before.

Anyone have any ideas on the alternator? Probably just a good charge was all it needed.

THanks for the help everyone!
__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)
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  #11  
Old 09-11-2003, 11:41 PM
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Join Date: Jan 2002
Location: NY
Posts: 500
This old thread came up when I did a search for high altitude shift problems. I had same experience with 92 600SEL, 722.3 tranny. During my vacation trip from NY to CA I've noticed progressively worse shifting with higher altitude, above about 4000 feet. It was very rough at the Pikes Peak at over 14000 feet. I'm not sure, but maybe the problem is in the modulator adjustment? It was done at the East Coast sea level altitude and required some compensation for the higher elevations. On my previous trip to CO in ML430 (722.6 transmission) - no problem.
Mike
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  #12  
Old 09-12-2003, 10:00 AM
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Join Date: May 2003
Location: DC Metro Area
Posts: 365
80/20 mix at high altitudes

I noticed that you said that you have an 80/20 mix of water/antifreeze. I seem to remember from chemistry that water boils at a lower temperature at higher altitudes (less pressure). So - maybe you're getting too much boiling from the weak mix that you've put in the car. The antifreeze raises the boiling point of the coolant mix - in addition to lowering the freezing point.

I know that more water makes for more efficient heat transfer - but perhaps your weak mixture is being counterproductive at high altitudes.

Just a thought.

Regards,
Troy K.
1995 E420
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