bleed screw on the 4.5?

[4NDELIT]

Anybody know where the bleed screw for coolant is on the 450SL? I've been losing a little bit of coolant, and it's starting to heat up a little, and I can't find a bleed screw to purge any air there is in the system. Any help would be great.

[ctaylor738]

I just looked through the cooling system sections of the CD for the 78's. No mention anywhere of a bleed vave.

My 380SL has a vent hole on the front of the thermostat that very occasionally will discharge a small amount of coolant.

The manual says to fill at the tank and then run the engine at varying speeds until fully warmed up, then check the coolant level.

On the Vintage Forum, the advice on the 4.5's is to fill them by removing the upper radiator hose (at the radiator end) and filling the system through the hose.

Hope you find your problem.

[4NDELIT]

thanks, I've started tracking down my coolant problem... it seems that my auxiliary fan does not come on any more (had this problem before, blew a fuse but the fuse is good now). I'm gonna try to see if it's just the switch that's gone, or the fan itself. Anybody know what wires to jump to bypass the switch? It looks to me like it bolts on to the water pump/thermostat housing (#125)

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If you touch a wire to the connetion on top of the aux fan switch and touch the other end of the wire to any clean spot on the block, the aux fan will kick on. To do this you have to have the wire plug that attaches to the top of the aux fan switch connected.

[4NDELIT]

thanks for the help... the fan spun up, so I guess the switch is dead. Another thing... when I start up the car, the regular fan is going full blast... this mean my fan clutch is seized? It takes forever to warm up, but I just figured it was a huge solid engine... guess the problem goes deeper than that. Thanks a bunch for the help!