Heater servo questions - PeachParts Mercedes-Benz Forum

highdigger · #1 03-13-2014, 06:33 PM

My '80 wagon was gushing brownish fluids around the heater servo, so I took it to my mechanic and he quickly (without really looking at the unit) told me that it was cracked and the replacement part would be $1600+. I've been planning to sell this wagon so I could focus on my w115, so this came as a vexing shock to me. I removed the unit as best as I could (given that I've never done any work like this before) and I'm trying to figure out:

A) if the unit can be salvaged/what might be the problem. I don't see any obvious cracks, just some gaps and some rubber/putty? in a few spots.

B) if I should try to find another servo at a salvage yard.

C) ?

Also, obviously, there's a rust issue somewhere and the unit could use some cleaning. Should I remove the lower unit and clean it out? Any help would greatly appreciated. I'm new to this stuff.

highdigger · #2 03-13-2014, 06:36 PM

Doesn't seem to be letting me attach more than one image at a time...

uberwasser · #3 03-13-2014, 06:55 PM

Very few have tried to refurbish one of those themselves. They aren't especially complex inside, but tend to be pretty well eaten up with corrosion which is what leads to failures like this. The only folks who I've seen do it themselves had three or four bad servos on hand and they were able to make one good one out of it.

The good (?) news is that you don't have to fork over $1600 for a new one. You can get a good used one on eBay for a few hundred. Who knows how long it will last, but I hate to say it, you're planning to sell the car...

Or, if you would feel better about it, you can get professionally rebuilt ones on eBay or from Performance Analysis Company. If they have one in stock, you can get a rebuilt one with a new plastic body for $300 or a rebuilt one with the more durable aluminium body for $600. You'll send them your old one for a core charge refund so they can rebuild it.

Lastly you can try your luck at the scrap yard. I found an aluminium servo there and got it for $15. The aluminium ones don't fail nearly as often.

uberwasser · #4 03-13-2014, 06:56 PM

Here's a recently rebuilt, but used, servo at $220 buy it now price. Not bad.

Mercedes Heater Control Valve Servo Unit W107 W123 W114 | eBay

whunter · #5 03-14-2014, 01:19 AM

Quote:

Originally Posted by highdigger

My '80 wagon was gushing brownish fluids around the heater servo, so I took it to my mechanic and he quickly (without really looking at the unit) told me that it was cracked and the replacement part would be $1600+. I've been planning to sell this wagon so I could focus on my w115, so this came as a vexing shock to me. I removed the unit as best as I could (given that I've never done any work like this before) and I'm trying to figure out:

A) if the unit can be salvaged/what might be the problem. I don't see any obvious cracks, just some gaps and some rubber/putty? in a few spots.

B) if I should try to find another servo at a salvage yard.

C) ?

Also, obviously, there's a rust issue somewhere and the unit could use some cleaning. Should I remove the lower unit and clean it out? Any help would greatly appreciated. I'm new to this stuff.

Evil Servo related threads
http://www.peachparts.com/shopforum/diesel-discussion/336579-evil-servo-related-threads.html

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highdigger · #6 03-15-2014, 03:32 PM

Thanks uberwasser and whunter. I've been reading through the evil servo related threads and I'm not sure yet whether i want ultimately to bypass the system, but in the mean time I was thinking of checking the parts yard for another servo so the car is functional.

Can I just install the new (old) servo, or is there something else i need to know/do? are all w123 servos the same or should i focus on specific years?

Thanks.

cooljjay · #7 03-15-2014, 10:05 PM

Here is an order of things that should be replaced...

Aux water pump, may be able to clean/grease old one...FUSE..it
Amplifier behind glove box liner
Foam Sensor tube behind glove box...

This should cause it to work...unless...you have vacuum leaks or bad vacuum pods..

Now I would not get a used servo at a junk yard unless it is the newer aluminum bodied unit. The same goes with the amplifier...If your lucky you may find one with a new servo and amp....these servos were only used on 1976-1978 cars...minus 240D's and euros..