Author Topic: Radiator fan running continuously  (Read 157 times)

Thegger

  • Enthusiast
  • *
  • Posts: 66
  • W116 Enthusiast
  • Location: Norway
Radiator fan running continuously
« on: 30 November 2018, 12:35 AM »
On my 1977 450SE it starts when I start the car.
Any known issues with this? My temp sensor is working fine.

oversize

  • W116 Addict
  • ****
  • Posts: 1,311
  • W116 Nut
  • Location: Melbourne, Australia
Re: Radiator fan running continuously
« Reply #1 on: 30 November 2018, 12:38 AM »
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

  • W116 Addict
  • ****
  • Posts: 1,311
  • W116 Nut
  • Location: Melbourne, Australia
Re: Radiator fan running continuously
« Reply #2 on: 30 November 2018, 12:46 AM »
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

  • Enthusiast
  • *
  • Posts: 66
  • W116 Enthusiast
  • Location: Norway
Re: Radiator fan running continuously
« Reply #3 on: 30 November 2018, 02:41 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

  • W116 Addict
  • ****
  • Posts: 1,910
  • MBCA Member
  • Location: Phoenix, AZ, USA
Re: Radiator fan running continuously
« Reply #4 on: 30 November 2018, 01:07 PM »
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.
Stop paying for animal cruelty and slaughter. Go vegan! https://tryveg.com/

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, 346,000+ Miles