Have a 1995 E220 (W124) 160 000 km which runs hot (100-110) when driven
slowly around the suburbs (putting the baby to sleep stuff)
On a long trip at 130km/h it sticks at 80
I've spoken to a couple of other owners who say it should stick at 80 no
Thought of having the radiator (and engine?) flushed.
Thanks in anticipation.
When running hot, does the aux fan come on? Have you been good about the
type of water and coolant used in your radiator? Open the cap on the top of
the radiator, when cold, and look at the tubes inside--any white deposits?
Now with the cap off, start it up and when it's hot see how well the water
flows. If it's an anemic flow rate, could be the thermostat.
Thanks for the reply John. No I haven't been particularly careful about the
coolant. Have done regular agency services though.
Regarding the auxiliary fan. This remains something of a mystery to me. My
reading (Haynes manual) has lead me to believe that the auxiliary fan comes
on when the temperature of THE AIR behind the radiator passes some given
temperature. The operation of mine follows this rule as when I stop. for
example to open my driveway gate, the auxiliary fan almost always goes on
but when the car is travelling along (and overheating) it doesn't. I'm sure
the operation is entirely logical but I've never really undrstood why it
wouldn't come on under a straightforward overheating scenario.
Presumeably white deposits indicate less than optimal flow?
Usually the fan temp sensor is in the coolant. But your fan is working so
I'd check to see about radiator deposits restricting flow. Radiator shops
can do a flow test but that's a last resort for me. Your eyes can tell you
what you need to know.
The gas engines typically run warmer under the conditions that you
describe - no harm so long as the temp. is below the dreaded red zone.
Diesels typically never exceed 80 degrees C except when climbing long hills.
Radiator cleaning is required when the engine runs hot at speed - lots
of air flow so that excludes the fans leaving only the thermostat or
radiator to blame.
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