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1981 240D
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I am the new owner of a 1981 240D with 120K miles on it. I've been driving it as my daily driver for the past 2 weeks without a problem (knock on wood). With that said, I've noticed a few of things.

1. It taks about 5 to 7 tries to start her up when it's 25 degrees or lower.
2. Ever since I got her I've noticed the idel is rough in first gear when stopped. But when I hit the gas she seems to smooth out. I've also slipped her out of gear and in to neutral while at a light and the rough idel dissipates.
3. I've added anti-gel a full tank of fuel and the fuel gauge stopped working. When I filled up and put more anti-get in it, it started to work again.

Do you think it sounds like a valve adjustment? If so how much will it cost? In the future I am planning on doing it myself.
 

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84 300TD, 2004 E320 wagon, 2006 CLS55,
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1,051 Posts
There is a idle adjustment on the Injection Pump. If the idle is low then the car may not want to stay started until it's warm. There are plenty of tutorials on how to adjust the valves if you are mechanically inclined/have the tools/space.
 

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77 280E, 78 450SEL, 86 300E, 87 300E, 90 300E, 92 400E & 4 scooters
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233 Posts
I'm 47 and my 82 y/o mom showed me how to start a MB deisel in cold weather. This comes fom a MB pamphlet she got with her 80's 300CD bback in the day.

1) turn the idle knob counter clockwise all the way
2) ignition on until GP light goes out
3) accelerator pedal to the floor and hold it there
4) CRANK and keep it cranking. 10-15 seconds maybe

with a block heater this should work on the first try. w/o it should work on the 1st or 2nd try.

The fuel guage sending unit can be accessed by removing the first-aid box. Its located on the top of the fuel tank (right under the first-aid kit). Remove the sending unit carefully and clean it up. This fixed my erratic fuel guage needle. Carefull, it's delicate.
 

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77 280E, 78 450SEL, 86 300E, 87 300E, 90 300E, 92 400E & 4 scooters
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233 Posts
If you have a feeler gauge you can adjust the valves. Search here I'm sure you'll find the spec's.

2years ago I purchased a sweet deisel for $500.00 because it was a non-runner. I adjusted the valves and she fired right up, I've been driving her eversince. Happy day!
 

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2008 E320 Bluetec, 1988 560SL totalled unto death). 1997 Dodge Ram 1500, 1983 300CD
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1,342 Posts
valve adjustment

Should be done every 12k miles on your car. Fairly easy DIY with the proper tools (specially bent wrenches and a feeler gauge). If you choose to have it done in a shop, should be one hour labor cost.

All a diesel has going for it is compression. Don't neglect the valve adjustments and you will be rewarded with a smooth running, reliable engine.
 

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My independent M-B shop quoted me $725 for a valve adjustment and a timing chain replacement (done at the same time). My car is a 1985 300D with 167K miles on it and the timing chain has never been replaced. I'm doing this as preventative maintenance since it's less labor to do it in conjunction with a valve adjustment, or so I've been told.

So does this seem like a fair price? I've had both my cars maintained at this shop and they do good work, but that seems pricey to me. Some of the other stuff they've recently quoted also has me wondering about their pricing too.
 

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2008 E320 Bluetec, 1988 560SL totalled unto death). 1997 Dodge Ram 1500, 1983 300CD
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1,342 Posts
Cost

Not familiar with chain service on your 123 but that seems is probably in the right range. Most of the cost would be in labor. On my V8, new chain with new guides, tensioner rail and camshaft oilers is about $800.

Subtract the hour labor for valve adjustment and the remaining sounds very reasonable to me.

Find out what thier labor rate is. If it is in the $85 to $110 per hour range it is the going rate.
 

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77 280E, 78 450SEL, 86 300E, 87 300E, 90 300E, 92 400E & 4 scooters
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233 Posts
OMG, My indy charges $65/hr.

He always figures out the issues correctly and quotes me his cost for parts and asks if I'm able to find parts cheaper.

I spend an hour or two searching for parts, save $300-$600 getting them myself. He installs them and life is good. It's always a good expieriance.
 

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77 280E, 78 450SEL, 86 300E, 87 300E, 90 300E, 92 400E & 4 scooters
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233 Posts
Oh, yeah, if I asked my indy to adjust my valves, he'd throw a wrench at me, call me a wimp and tell me to do it myself.

Actually, he'd take his time and explain the proper way to adjust the valves and sugest I give it a go. And then tell me to bring the Benz to his shop to see if I did a good job.
 

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1984 300D
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5,070 Posts
The Glow Plugs will sta on longer that the light indicates if leave your Key in the Pre-glow position until the Glow Plug light goes out; just leave it in that position for another 20 seconds or until you hear the Glow Plug Relay click off and attempt to start.

Instead of listen for the click of the Glow Plug relay some people watch the interior Light. When the Key goes into the Pre-glow position the Interior Light will dim a little; when the Glow Plug Relay turns off the Interior Light will brighten.
(If you leave the Key in the Pre-glow position regardless of what the Glow Plug light does the Realy stays on for about 30 seconds.)

Also in cold weather you can turn the Key Back of and go through the Pre-glow routine agin and again preglowing for about 30 seconds.

Many forum members have said that switching to synthetic Oil helps cold weather starting because it allows the Engine to spin faster.

I have also read that after 200-300 miles of driving with cynthetic Oil if there was any sticky Piston Rings it can free them up. Better compression from unstuck Rings would also aid starting.

Make sure your Battery Cables and Engine to Chassis Ground strap are making good contact and in good condition. On US models the Chassis to Engine Ground strap is about where your Feet are under the Car.
 
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