Hey guys,

Working with my 1980 300sd w116.

This car was 2 days from going to the junkyard becuase its not exactly pretty and could not pass emissions. After chaning the normal maintanance items, it now passes emissions. The vacuum system in the car is a mess and of course there is no heat.

I remember reading information on bypassing the servo and instead placing a hose or valve in place so the heat can be turned on and off for winter/summer.

Was wondering if anyone knew where the article was, any suggestions or tips on how to do this, or anything else like which hoses to connect together, size of pipe I need, and so on.

AC also does not work of course, sysem completly void of any refridgerant - hope that one wont be a mess as well. Probably will be, but at least I have 6 months to figure that out.

Thanks!

bumpady bump

Our 300d had a problem when we bought it with heat and ac. The heat, when on, blew red hot, or we turned it off. The ac didn't cool at all, if I remember. I ended up ordering a replacement for the ac\heater control valve (mono valve solenoid repair kit) for $35 from ***************. This may or may not be your problem, but it sure did the trick on ours. AC and heat both work great since then. And it was an easy, 5 minute, 2 screw fix! If you check out their site, look under your model and "AC & Heat". They might have what you're needing. Good luck with your project. Lee

__________________
"Knowing is not enough, we must apply.
Willing is not enough, we must do." Goethe

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1951 Chevy 3100

2003 Indian Chief Roadmaster

1983 GMC 1 ton Dually

1982 Chevy 1 ton Dually, service body (sold)

'90 GMC Suburban 6.2 "SS Veg-Burban"
(single tank WVO\diesel conversion) SOLD

'81 300D ~ Mama's car...my job (now my car)(but still my job) SOLD

'83 300sd ~ rescue car SOLD

2005 Ford Taurus (Mama's new car)(NOT my job!)

You have the dreaded servo and that's a different beast than the much simpler monovalve.

You can bypass it without too much trouble. There are bypass kits available if you don't want to cobble it together yourself.

__________________
Joe

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1980 300SD - 495k miles - 'The Ambassador'
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Former Family Members
95 C280
73 280SEL
90 300D
87 300SDL (X2)
86 560SEL
84 300D
80 300SD

I wouldn't think it would be too difficult.
Hose from head goes into aux coolant pump then into servo thingy.
than into the firewall.
So just bypass the servo thingy put in a valve so you can shut it off.
It shouldn't matter which way it enters and exits the firewall It's just a heat exchanger right?..There may be a swizzle where the aux coolant pump
is controlled by the servo somehow..not sure..you should research that .
But if that was the case a simple switch inside the cabin somewhere can turn the pump on and off.