Hi Guys

Had copied the following post from one of th treads from this forum. If i am not wrong the end story once you read out this tread tells us that if we have suppose 100 C raditor cap during summers it will open up and release the hot pressure from the raditor on 100 degrees C temprature of the coolant.

If i am wrong pl correct me and guide me as i have 140 degrees coolant reseviour bottle cap. I personally feel if i change it with 100 that might bring the temp down in my car. My car presently run in between 100-105 in rush area. Just wanted to double cross this from you guys if it helps me ....



Pressure(kPa) Boiling point: 'C 'F
47 80 176
68 90 194
100 100 212
140 110 230
195 120 248..."

Be careful! You have to remember that the pressure in the system is going to be that cap pressure (where "100" = 1.00 Atmosphere, or Bar) OVER ambient atmospheric pressure (which is 1.00 Bar at sea level, and a little less up in the mountains"), so that chart might be a little misleading to a lay reader who doesn't know to add ambient pressure to the system's pressure determined by the cap's release rating.
Example, that chart taken literally, using the cap "100" could mean sea level pressure -- same as ambient -- and thus offering no retention of pressure at all at sea level. In fact, the cap "100" allows for one atmosphere of pressure OVER ambient pressure (before releasing), or actually TWO atmospheres of pressure within the cooling system.
In other words, your chart implies that a "100" cap allows water to boil at 100 C or 212 F, whereas, in fact, that "100" cap will permit the coolant to rise to about 120 deg
before boiling, the equivalent of TWO atmospheres.

If you are saying that your '95 E320 with the M104 IL6 is running at 105C in traffic then this is normal operating temps. I wouldn't change a thing unless you approach 110 -120C.

__________________
dtf
1994 E320 Wagon (Died @ 308,669 miles)
1995 E300 Diesel (228,000)
1999 E300 Turbodiesel ( died @ 255,000)
2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop
2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army
BMW 330 xi 6 speed manual (175,034 miles)
2014 E350 4Matic Wagon 128,000 miles
2018 Dodge Ram 21,000 miles

I have also felt that there is no loss of coolant for the last 8000 KM, despite the car sometime in traffic jams shows the heat gauge in between 100-105. I am actually use to my prvious BMW's . Their temp gauges never move from the place once they reach the optimum temp.
Thanks for the tip