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Old 06-21-2010, 02:54 PM
ah-kay ah-kay is online now
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Join Date: Mar 2009
Location: San Diego
Posts: 3,597
I just fixed my overheating problem with my 300SDL but it may or may be applicable to your car.

1) Change out the overflow tank cap with a new one. I bought a 20lbs one from Autozone for $5, so it is not that expensive to try. Try to sqeeze the radiator hose after the car is at temp for a while. The hose should be pressurized and should stay pressurized for a day, may be longer. This is normal. If the hose is not pressurized then the cooling system is not air tight, most likely a leaky cap.

2) Check the aux fan can go on high speed. I do not know your car but there should be a thermostat-switch near the top of the radiator hose. It may be 2 prongs or may be 3 prongs. That is the trigger switch for the fan to come on. On my 300SDL, it is 3 prongs and if I shorted the 2 prongs connector and the fan will come on. The third prong goes to a single connector is cut in at 125/8C to turn off the A/C I think. Your car may DIFFER.

3) You can get a lower cut-in temperature thermostat switch. My 300SDL is 105C rated ( grey color ) for the fan to cut in. I bought a 100C rated ( red color ) to give it a better safety margin as it has the #14 head.

Hope this help. Good luck.
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.
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