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Radiator fan running continuously

Started by Thegger, 30 November 2018, 03:35 AM

Thegger

On my 1977 450SE it starts when I start the car.
Any known issues with this? My temp sensor is working fine.

oversize

That could also be sapping power! Do a search re checking fan clutch.
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

oversize

Which fan is it? Electric or engine driven? The temp sensor for the electric fan can be damaged by steam cleaning.
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

Thegger

Quote from: oversize on 30 November 2018, 03:46 AM
Which fan is it? Electric or engine driven? The temp sensor for the electric fan can be damaged by steam cleaning.

Its electric. I know the previous owner had the same problem. There is some bad insulation on the wires and mabe there is connection between them some place? I cant see it ofcourse, but thats my only guess.

Squiggle Dog

Maybe the relay which runs the auxiliary fan is shorted out and causing it to power on all the time. You can swap it with another relay (they are located behind the left side kick panel) and see if it changes anything.
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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Heated Seats, 350,000+