M104 versus M103: Operating temperature. - PeachParts Mercedes-Benz Forum

sanchezc · #1 04-09-2006, 10:58 AM

The temperature on my 300SE/M103 stabilizes around 80C, whereas the temperature on my E320/M104 stabilizes around 90C: is this by design, i.e. the case for everyone else here?

BTW sincere thanks to all who contributed to my previous "M103: ..." and "M104: ..." posts yesterday: very helpful. And keep your experiences coming!

This site is so enlightening, hats off (again) to its creators, maintainers and contributors.

anthonyb · #2 04-09-2006, 02:17 PM

The M103 is running cold. It should run around 87-90.

Educaid · #3 04-09-2006, 02:22 PM

I have a 1989 260E with the 103 engine and a 1993 300E with the 104 engine. Both run the same temperature; about 80 - 85 degrees.

suginami · #4 04-09-2006, 04:29 PM

My 1993 300E (3.2) with the M104 engine, ran consistently between 87-90, which is exactly the temp range the engines were designed to run at.

Any lower than that is not normal.

Ali Al-Chalabi · #5 04-09-2006, 08:54 PM

Thermostat on both engines is the same temp. Starts to open at 87C and fully open at 102C by design.

simmo300e · #6 04-10-2006, 09:39 PM

its a popular mod - at least in this part of the tropics - to replace the thermostat with one that opens at a lower temperature. Don't ask me why, this is what I'm told at my parts shop.

Anyway, this is fine with an older cooling system with a partially blocked radiator as the engine temp stays in spec. However, if you change out your radiator for a new one and replace the visco fan, as I did, the effect is that your engine never actually reaches operating spec and consequently runs rich all the time. Mine sat at just below the 80 deg mark whereas it used to be pegged exactly at 9-o-clock before the rad change.

Took me a while to figure it out but replacing the thermostat with the correct part sorted the mixture out.