Hello
when the car runs a long time the temperature indicator goes in the middle line of 80 and 120 Celsious degrees (175 and 250 F).
Is it normal?
In the other mercedes we have w115 220 it is always on 80 C (175F).

When the temp is up, turn on the heater,
if the temp drops, the problem is the radiator.

A radiator can "look" good physically and not cool.

A radiator shop should have an infrared hand held temp sensor to ascertain the condition of your radiator.

the temp drop from the top to the bottom is important.

Very simple devices,
falling water heat exchangers.

Hello and thanks for the reply.
Tha radiator is knew.

I would suspect a weak fan clutch. I would also replace the radiator cap, they wear out and the pressure they hold lowers.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

The gauge reading is well within the normal range but the fan clutch should keep it below 100 C. My 73 280c stabilizes at 195F on a 105 degree day in slow city driving. New cap and new fan clutch.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

.

If the heat drops you have a bad radiator? How is that? If you increase release of heat by allowing it to go through the vents with the air, naturally the temp would drop, or am I missing why this would be indicative of a problem?

Thanks!

__________________
1985 300D (CA, 173K)

Dynamite Biodiesel Co-op, Phoenix,AZ

By turning on the heater you are filling the heater core which increases the capacity of the cooling system. The theory is the radiator is partially plugged (restricted) so adding another radiator i.e the heater core, provides more radiator surface to dissipate the heat. This theory only works on a system that has a heater valve. Some cars use only a blend door to shut off hot air and the core remains filled at all times.

__________________
81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

I've had more trouble with thermostats than with any other single cooling problem--I'd replace it before trying anything else--good luck


Tim Kraakevik
kraakevik@voyager.net
Four 114's, Four M110's