Author Topic: Servo replacement with Mercedes Fix unit  (Read 277 times)

jjccp

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Servo replacement with Mercedes Fix unit
« on: 14 April 2019, 01:29 PM »
I spoke with Davis who makes the unit. He took the time to answer my questions and I ordered one. Here's what came in the package. I'll start installing it soon. My ultimate goal is to get the air conditioning working again. I've been reading everything I can to see what the best approach will be to get the a/c going again and would appreciate and tips or advice.

1977 280 SE
1979 6.9 #6846

Harv

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Re: Servo replacement with Mercedes Fix unit
« Reply #1 on: 14 April 2019, 02:21 PM »
I believe Davis had an account here and even posted a few times.
1980 300SD
1983 240D
2000 E55 AMG

OLDGOLD

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Re: Servo replacement with Mercedes Fix unit
« Reply #2 on: 14 April 2019, 06:48 PM »
I bit the bullet on the Unwired Tools ACC servo upgrade last year and it was one of the best things I ever did to my car. There are some things that are better left stock, the servo isn't one of them!

jtwoods4

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Re: Servo replacement with Mercedes Fix unit
« Reply #3 on: 15 April 2019, 04:03 PM »
I went a little bit different route and both of my w116 300SD. I replaced the cracked servo housing with the aluminum housing replacement. Works outstanding and connects to all the existing factory connections. I really don't remember the company I purchased from but it did a quick internet search and came across this link I'm pretty sure this is where I got it. It was years ago.

http://www.perfanalysis.com/climate-control/acc-version-i/
1980 300SD

jjccp

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Re: Servo replacement with Mercedes Fix unit
« Reply #4 on: 18 April 2019, 12:54 PM »
jtwoods4,

I put the aluminum housing servo in my 6.9 several years ago and it's still working fine. I went a different route this time because it only costs $350 for the Mercedes Fix unit. Beside the servo cracking, it's still prone to other types of failure.

Now that I have my car tore apart, I've found that the little auxiliary water pump is bad. I can't believe what some people want to charge for them. I took apart the electric motor and did my best to troubleshoot it, but I can't get it working and I'm not spending $600 for one.

I wonder if anyone has a suggestion for an alternative pump that might work or does anyone have a working auxiliary water pump I can purchase?

1977 280 SE
1979 6.9 #6846

daantjie

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Re: Servo replacement with Mercedes Fix unit
« Reply #5 on: 18 April 2019, 01:04 PM »


I wonder if anyone has a suggestion for an alternative pump that might work or does anyone have a working auxiliary water pump I can purchase?

Yup, I ran into this a while ago, those pumps are horrendously expensive, and do not even think of putting in a crap MTC brand one.  Here is one I found:

https://www.ebay.com/itm/Mercedes-Benz-Sprinter-Auxiliary-Electric-Water-Pump-BOSCH-0392020026-MB-/132679176767?_trksid=p2349526.m4383.l4275.c1#viTabs_0

Full disclosure, have not tried installing this one as my original still works fine, but if it does go tits up I will for sure swap it out with this bad boy.

Also on amazon:

https://www.amazon.com/Bosch-Electric-Water-Pump-0392020026/dp/B0083HR744



Daniel
1977 450 SEL 6.9 - Astralsilber

jjccp

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Re: Servo replacement with Mercedes Fix unit
« Reply #6 on: 18 April 2019, 01:12 PM »
Daniel,

Thanks for the link. That's a more reasonable price compared to the other one's I've seen. Just curious, how did you determine that this one is compatible?
1977 280 SE
1979 6.9 #6846

daantjie

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Re: Servo replacement with Mercedes Fix unit
« Reply #7 on: 18 April 2019, 02:13 PM »
Well to be honest, I eyeballed the thing, looked at the connector which should fit, might need minor modification on the plug side.  Also it runs on 12V, so all is good there.  I would say if you want to be absolutely sure you would need a flow/pressure test of sorts to compare them, but I would be shocked if there is much difference between the 2, other than the knee buckling price :o
Daniel
1977 450 SEL 6.9 - Astralsilber

jjccp

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Re: Servo replacement with Mercedes Fix unit
« Reply #8 on: 18 April 2019, 05:04 PM »
I agree with you. An auto engineer friend of mine told me that without knowing the actual specs, if the inlet size and outlet size of a pump are similar to the subject pump and it's 12 volts, it should be fine.

I think you are on to something, thanks. I'm checking a couple of other sources and it they don't pan out, I'm going to try your idea.

Of course, the originality police would have me buy the OEM unit for $600. I like keeping everything as original as possible, but I won't lose any sleep about using a substitute.
« Last Edit: 18 April 2019, 05:17 PM by jjccp »
1977 280 SE
1979 6.9 #6846

jjccp

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Re: Servo replacement with Mercedes Fix unit
« Reply #9 on: 20 May 2019, 08:37 AM »


I wonder if anyone has a suggestion for an alternative pump that might work or does anyone have a working auxiliary water pump I can purchase?

Yup, I ran into this a while ago, those pumps are horrendously expensive, and do not even think of putting in a crap MTC brand one.  Here is one I found:

https://www.ebay.com/itm/Mercedes-Benz-Sprinter-Auxiliary-Electric-Water-Pump-BOSCH-0392020026-MB-/132679176767?_trksid=p2349526.m4383.l4275.c1#viTabs_0


Full disclosure, have not tried installing this one as my original still works fine, but if it does go tits up I will for sure swap it out with this bad boy.

Also on amazon:

https://www.amazon.com/Bosch-Electric-Water-Pump-0392020026/dp/B0083HR744

Daniel,

I owe you a big fat thank you. I ordered that pump and it works great!. If fits perfectly and the 12v connector slips right in. I would challenge anyone to notice the difference in looks or function. And of course, the price can't be beat.

Thanks again,
Jim
1977 280 SE
1979 6.9 #6846

jjccp

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Re: Servo replacement with Mercedes Fix unit
« Reply #10 on: 20 May 2019, 08:48 AM »
I've installed the Mercedes Fix unit and so far everything looks good. I'll post some pics when I'm finished tidying up everything.

Davis, who makes the unit gave me some great advice. Vacuum switch #14 behind the glove box often fails and the result is that only the Defroster button works. He suggested just putting a manual switch in place of the original switch for testing purposes. So far I have all functions working correctly except my air conditioning, but I pretty much knew that was kaput.

Now I'm on my next quest to get the a/c working again.

Thanks again to daantjie (Daniel) for supplying the link for the replacement auxiliary water pump. That little bugger works perfect and the difference between paying $600 and $72 is very satisfying. Once again proving that this site is so helpful when working on our old cars.
1977 280 SE
1979 6.9 #6846

daantjie

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Re: Servo replacement with Mercedes Fix unit
« Reply #11 on: 20 May 2019, 10:36 AM »
Glad to help ;)
I love easy and cheap fixes as I'm sure we all do in this crazy 116 world  8)
Daniel
1977 450 SEL 6.9 - Astralsilber