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Old 08-05-2001, 06:34 PM
Vhunter Vhunter is offline
Registered User
Join Date: Apr 2001
Location: Near Omaha Nebraska
Posts: 19
Question Question on fan turn on temps

I have an '87 300SDL, and the engine temps. seem to get higher than I think they should.
I checked the CD data sheets for the car, and it looks like the Aux fan turns on at 105'C in "low" speed (resistor in line), and steps up to high speed (resistor bypassed) at 115'C.

This seems to be a bit high to me, and makes me worry. The engine does get up to about 105-110 at times. Is this normal?

On another point, at what temps should the visc. coupled fan driven by the engine start to engage/tighten up? I have had the engine temp at 105C by the guage, and have watched the fan while running the engine RPM up a bit from idle.. it does not look like the fan speeds up at all at this temp.. is that the way its supposed to be? Kind of like a constant speed (which rises with the air temp), no matter what the RPM of the engine?

Any insight to the visco-fan or comments on the fan-engine temp switch would be helpful!

Thanks in advance!
1985 300D - 190K Miles - 26 MPG on first trip home - getting rust fixed and repainted.
1987 MB 300 SDL - 238K miles - Sold
2003 DC Ram 2500 QuadCab 6 speed, 4x4 Cummins - 82K miles - 20+ MPG
1999 VW A4 Jetta TDI 5 speed - 83K miles - 50+ MPG is easy!
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