I am new to the MBNZ world. I have a 1991 420sel that I have owned for approximately 3 months. Since weather temperatures here have increased lately (95-105F), I have noticed some strange activity with the heat gauge. Normal operating temp on this car is usually just above the 80 mark on the temp gauge. However, with hotter heat, I have noticed that at slower speeds and when pulling hills with a/c on, the temp is rising about 2 guage needles widths above the guage mark following the 80 mark (I cannot recall if this mark is numbered). Is this normal or should I be concerned?
Any input would be greatly appreciated

------------------
MrRoche
1993 300E
1991 420SEL

If the car has been serviced properly, it is probably not the radiator. More likely suspects are the thermostat OR the viscous clutch on the fan. If the latter goes bad the fan just won't do its job. Ed

I go about this the same way on every car.

Step 1 is to replace the thermostat. Now drive the car and come back and turn off the engine. Immediately open the hood and hold the fan blade in a position so you can get one hand on the radiator. If the radiator is HOT, the auxillary fan and or the fan clutch on the main fan is bad.

Be sure to check the auxillary fan fuse...

------------------
Benzmac:
Donnie Drummonds
1991 GMC Syclone
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Benzmac,

Confused, hold the fan blade and put your hand on the radiator?? Is it safe to hold the fan blade to see if it will rotate?? Please re-explain.

Also, could it be that he has 100% water instead of 50-50 mix, that did the trick for me?

------------------
'89 420 SEL
'90 300 SEL
'84 300 SD (sold it)

Please read Benzmac's post again. He did say with the engine off!! This is a clutch fan it does not engage while the engine is off, but if you had just turned off the engine it may still free spin for awhile.

yal
88 230E (W124)