I lowered 400E's temperature! - PeachParts Mercedes-Benz Forum

carman850 · #1 08-15-2002, 08:56 PM

This is a hot summer, with A/C on, the coolant temperature of my 92 400E fluctuates between 100 and 110 in the city, 100 on highway drive, turning off A/C makes little difference.

My coolant is new, auxiliary fans are in good condition, so I couldn't believe this high temperature is normal, my Ford Explorer's coolant temperature was steady at middle even when I was towing 1500 lbs tent trailer, going uphill with A/C on!

I had been suspecting the viscous Fan clutch for a while, but since the new part is so expensive, why just nail the viscous fan clutch to the pulley, and let it on all the times? I decided to give it a try, I just loosed one of the four 10 mm bolts on the viscous fan pulley, after a few turns, it reached the viscous fan, applied just enough pressure to the viscous fan to hold them together.

I then gave it a test drive, the result was amazing, now the temperature shows steadily at 90 degree regardless of driving condition, just like any other car I have owned. It didn't run cooler than this even in last winter(Canadian winter).

I can feel fan blowing at rpm higher than 1500, my question is if I can keep it like that, is there any thing harmful?

jsmith · #2 08-15-2002, 09:35 PM

there's a mod on this in the performance forum that keeps the fan locked till the normal cutoff at around 3k rpm. the way you did this i think it is locked and will stay locked past the cutoff. the fan's not designed for that but aside from losing a few horses i don't think there are downsides. in the winter you'd probably have to unlock it...

carman850 · #3 08-15-2002, 10:05 PM

Thank you Joe, I found that thread.

I am going to do the same. I often rev the engine near red line, it'd better do cutoff at 3000 rpm, I worry those fans may not be able to handle 6000 rpm, and the noise is really loud at 4000 rpm, like a air cooled 911 turbo.

engatwork · #4 08-16-2002, 05:14 AM

carman - if you don't mind please post that link.
thanks

carman850 · #5 08-16-2002, 10:13 AM

Here is the link:

M119 Viscous Fan mod & problems with aux. fan resistor-mod

jsmith · #6 08-16-2002, 05:43 PM

there were a few different tracks on that thread. i followed one of them - the one by a member from the Philippines who installed a "tropical duty" viscous fan clutch to solve his overheating problems. i am curious as to what our resident expert's opinions are on this. it simply locks at a lower temp than the stock one. i've found one at an online parts specialist and was quoted $159. with the kinds of summers we are experiencing here in the east coast, i think that this mod is practical since it operates the same as stock otherwise. it may even negate the need for the resistor mod which i am dependent on in my car these days.

400E · #7 08-17-2002, 09:18 AM

I printed up Stu Ritter's instructions and took them to my independent. Instead of drilling a hole in the bimetal strip, he simply used the screw-on top from a spark plug, ground it down to about 3-4 mm high, and slipped this over the pin and then put the bimetal strip over it. It is now bowed UP due to the spark plug ferrule. It has the same effect as Stu's fix but is a little easier to get on and off (we think), since you want to be able to disable it for winter.

Makes a dramatic difference in engine temp in these days of high ambient temps, and it does cut out at 3600 RPM. You ABSOLUTELY do not want your fan to be coupled at a higher speed since the centrifugal force at higher RPMs could cause some REAL damage.