13 I seem to be running hot. What should I do?
Description
This article is from the VW Technical FAQ, by with numerous contributions by Jan Vandenbrande others.
13 I seem to be running hot. What should I do?
A: Check and do the following.
- Check your coolant level
- Check the concentration of your coolant
- Clean your radiator fins (do that with every wash)
- Check whether the fan still comes on at the correct temps
- Check whether the fan still works at all! Some cars have 2 fans
and one motor (a la Audi). Check whether the belt is still OK.
- Your temperature sensors may not be working right.
Some cars have SEVERAL sensors (one screwed in the radiator,
one exposed to the air above the engine)!
Also make sure the contacts are ok...battery acid
may do a lot of harm. Also check the system ground to those sensors.
Some suggest to drop the sensor in boiling water and see what temp
you read.
- Flush the system, check for calcium deposits inside the radiator
and tubes and check the thermostat.
Using destilled water in your mixture will prevent any deposits from
happening.
Your mixture must not contain more than 60% coolant! Otherwise the
heat transport effect will deteriorate.
- Check the thermostat (see whether it opens at the desired temps
to the required opening). Note: Thermostats do get lazy after a couple
of years.
- Check whether you have the right water pump. Some aftermarket pumps have
smaller impellers and therefore do not pump adequately.
- Check whether the water pump (s) are still working. The impeller
on the mechanical pump sometimes gets detached.
On VR6 cars, also check the second, electrical pump.
- Check whether the bottom radiator hose collapses when the engine
is hot and running. Replacements exist that have internal coil
to prevent a collapse. Mostly A1 cars are affected by this.
- You may be running too lean
See also the performance FAQ for other measures.
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