Hello,
My ododmeter has begun to work intermittently. What do I look for first? I am located in Canada and I'm looking for a great place to get parts. I need an AC amplifier and a servo.
Thanks for your help Judy
Judy, might I ask: what garage are you visiting? Are they suggesting that you need an AC (usually stands for Air Conditioning) amplifier???? re the servo.... servo control for what?? you 79 diesel has a spinning cable to run your odometer via the speed indicator I would think.
cheers, guenter
She is talking about that monster climate control unit/heater valve unit used on her car and the W123...
As for the odometer... you need to check your cable first... at the transmission to see it is loose. Otherwise, you might need to replace the gears on the odometer.
It's the servo for the climate control system. The amp drives the servo which then makes the world go round. The servo is the highest failure rate device in these cars. The sevo brings together electric, vacuum and engine coolant all in one kludge design. MB didn't even design it, they got it from Chrysler.
The servos fail for a variety of reasons, one of the main ones is the bottom made of plastic where the hot coolant flows cracks and they start leaking. I replaced my last one about 7 years ago. I got one from a small company in Tennessee, Performance Analysis. They sold servos that were made with a cast aluminum bottom half where the coolant resides. This eliminates the cracking problem. I think it was $600, but it was also warranted for 1 yr and then had a lifetime guarantee where they would replace it for $100 if it failed. Now mine has a very tiny weeping leak, but not enough to warrant replacing. Overall I've been very satisfied, but eventually I expect to have to use the $100 warranty.
There is also an aftermarket conversion kit that replaces the whole servo/amp system with a microprocessor and solenoid valve arrangement. TG on here has installed one and I'm sure can tell you more. Last I heard he was very happy with it. Since you need both a servo and amp, that could be the best way to go as it gets rid of the whole crap system.
One thing I would definitely not do is buy either a used servo or an amp from a salvage yard or similar, where you don't know what you're getting. New ones are expensive, but trying to buy a used on is a losing strategy. I've seen them on Ebay where they are being sold as "pulled from a working car", etc., which is meaningless. It could be
10 years old and from a car that ran, but the climate control didn't work.Regarding the odometer, is it just the odometer that is not working, but the speedo is OK? If so, then it's the odometer itself. It can be replaced or rebuilt. Pulling the instrument cluster is fairly easy. I've seen places online that rebuild speedo's for you.
Good luck with the car.
you 79 diesel has a spinning cable
Interesting... you can convert it to a Manual Heat Control for far less.
The retrofit kit that replace that original servo is rediculously expensive... Performance Product sells them for $1800!
The retrofit kit can be had here for reasonable price... to maintain automatic control...
There are some speedometer shops that sell repair kits - the little gears that your car needs. Do an internet search for "Speedometer repair"
I own a '80 300SD - for 28 years - and replaced its cursed servo and amplifier with a digital retrofit climate control. It's made and sold by a Tucson AZ company.
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