when the car is cold should the fan spin freely or be hard/impossible to turn? i've always thought that the fan was free-wheeling until the temp was achieved for the clutch to lock up and make the fan spin.

thanks in advance

g

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James 4:8

"...let us put aside the blindness of mind of those who can conceive of nothing higher than what is known through the senses"
-Saint Gregory Palamas, ---Discourse on the Holy Transfiguration of Our Lord God and Savior Jesus Christ


Centrally located in North East Central Pa.

When the fan hasn't been spinning for a while - like overnight - the fluid settles effectively engaging the fan. It's common to hear the whoosh of an engaged fan for a few seconds during a cold start.

Sixto
83 300SD

i'm pretty sure my fan is engaged at times when it shouldn't be.

__________________
0o==o0

James 4:8

"...let us put aside the blindness of mind of those who can conceive of nothing higher than what is known through the senses"
-Saint Gregory Palamas, ---Discourse on the Holy Transfiguration of Our Lord God and Savior Jesus Christ


Centrally located in North East Central Pa.

as sixto has described there are times when the fan might be partially engaged without it being exposed to the requisite temperature.

The easy way to figure if the fan is freewheeling is to check it after it's been running for a bit. Pop the hood and use a rag folded up and attempt to gradually interrupt the spinning fan's blades. A working clutch will allow the interference from the rag to stop the blades from spinning in a couple seconds.

Even a perfectly working clutch will have the fan spinning most of the time the engine is running, because even when it's cold there is some coupling between the blades and the clutch, but the fan is just barely coupled and it's easy to stop with a bunched up rag or something similar, a piece of cardboard of a folded up news paper or something like that.

It might be time to clean the radiator, condenser and space in between. Dirt can cause hot spots like right in front of the fan clutch.

Sixto
83 300SD

Mine was coupled pretty much all the time, hot or cold. I couldn't tell a difference in the amount if friction in the clutch. I went to all electric cooling and never looked back.

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i think i hear mine running fully locked up about 80% of the time and then it lets go irrespective of temp. i have some spare mercedes double electric cooling fans in the shop and i'm thinking of going that route. any tips or suggestions would be welcome!

thanks
g

__________________
0o==o0

James 4:8

"...let us put aside the blindness of mind of those who can conceive of nothing higher than what is known through the senses"
-Saint Gregory Palamas, ---Discourse on the Holy Transfiguration of Our Lord God and Savior Jesus Christ


Centrally located in North East Central Pa.

Upgrade to a 120-amp alternator or better.

Sixto
83 300SD

Theres not enough room between the OM606 and the radiator to fit an electric puller fan so instead I modified the aux fans. I replaced the passenger side belt driven fan with another driver's side electric fan and kept the belt in between. The PS cooler had to be bent out of the way to clear the second motor. I relocated the horn underneath the bumper.
http://i.imgur.com/UJm5GM6.jpg?1
I had to modify the mounting frame a bit because the mounting holes were different left and right but it worked. I also ditched the leaky plastic shroud for my own well sealed foam shroud between the fans and the condenser. http://i.imgur.com/aLYkylw.jpg?1
The wiring circuit for the driver's side fan is left as is so it still spins both fans when the AC is turned on. I added an 82c temp switch in the cylinder head near the coolant hose outlet. I'm not convinced this is the best location but it works for now. The temp switch triggers 2 relays which can drive both electric fans when switched on. It over rides stock input from the AC. When both electric motors are going it moves a lot of air through the radiator and it keeps the temp stable. The AC also seems to be a bit colder with 2 electric fans instead of 1. This car got a 150a alternator last year so there's no voltage drop when the fans switch on. I also installed a smaller 137mm water pump pulley a while ago but I suspect your 99 already has this.

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CENSORED due to not family friendly words