On a 1986 560sl, how can I check to see if the recirculating pump is working correctly? I think it is also referred to as the auxilliary water pump.

Rob, I think I wil keep an eye on this post as my 300CE has one too ! I cannot for the life of me work out if and when it is supposed to run, even with the help of a wiring manual. Mine seems to be as dead as the day it was installed ! If I jump 12 volts across the motor then it runs fine . . .Good luck !

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1993 190E 2.0L (Euro.) sold
1991. 500 SEL (Euro.)
1991. 300 CE (Euro.) sold
1993. 500 E (U.S. spec.)

I have problem with mind last week, so what I have done is use 12 volt to test it see it running or not. Afterward, I have break it down and see what happen inside, and I found that the communator of the motor is dirty, which stick with black substance, so, I use solvent and sand paper to recondition the communator, just like the electrical technican reconditioning the big electric motor.

Afterward, I put it all back together, it is running fine now.

may be you can try.

I am assuming that you're talking about the auxilliary water pump. When you check it by jumping 12 volts to it, you should use a good ammeter in series and check the current draw. If it is drawing more than 1.3 Amps, you should replace it, or clean it and see if you reduce the current draw below 1.3 Amps. If it is drawing more than 1.3 Amps it can, and probably eventually will, ruin the automatic climate control.

Good luck,

Thanks Larry, yes I mean the auxiliary water pump on the RH side of the inner wing which is in the heater water line. Is is meant to be running all the time or is it temperature dependant ? . . . I still cannot fathom its real purpose as I have not come across one of these before !

__________________
1993 190E 2.0L (Euro.) sold
1991. 500 SEL (Euro.)
1991. 300 CE (Euro.) sold
1993. 500 E (U.S. spec.)

This pump only runs when told to do so by the climate control. If the car has a rest mode, it runs in rest mode. Rest mode is for when you make a short stop in the Winter, maybe to run in to pick up the laundry, this pump will circulate hot coolant through the heater core to keep the interior warm.

Good luck,

. . . Thanks Larry. For some reason this pump is not covered too well in the manual, perhaps the service CD has a little more. We have temperatures in Dubai year round rarely dropping below 15 celcius so a heater is really not that much of a necessity. If this pump is required for the climate control ( in the cooling mode ) then I guess it is worth looking at . . . When I first lifted the bonnet ( read hood ! ) I guessed that as my car was European spec., this pump had something to do with the heating system. Looks as if it is a quick way of pumping some warm water around the block and into the car without going the long way round via the radiator. mmm ?

__________________
1993 190E 2.0L (Euro.) sold
1991. 500 SEL (Euro.)
1991. 300 CE (Euro.) sold
1993. 500 E (U.S. spec.)

Oh! so this mean that is not the recirculating pump?! so wher eis it located in the 300E???? and what for??