1974 Peugeot 504 diesel overheating

My 504 just got out of the shop last night for the brakes (it is
sporting a brand new vacuum pump), but now is apparently overheating.
There are wisps of steam coming out from under the hood, especially
when the car is idling at red lights for over 15-20 minutes.

If the car is at speed, this does not seem to happen.

Could this be a bad water pump, radiator that needs flushing, or
something else?

In the mean time, I just turn off the car at every red light for the
45 ~ 60 seconds of the traffic light cycle then start it up again.

 

When the car is at speed there is enough air being pushed over the
radiator to cool the engine so that makes me think that the pump is
OK. So might be a malfuctioning fan. Is the 504 old enough to have a
non electrical fan? It is possible the shop accidentally disconnected
either the fan or the sensor that controls it when they fixed the
vacuum pump.

Another way of cooling the engine if it is just the fan is to run the
heater. This transfers the overheating problem to you, but you have a
cooling system and it is less catastrophic if you get hot than the
motor. This trick has saved me twice from dead electric fans on hot
days in heavy traffic, which is just when you find out that the fan is
not working of course.

 

Hi,

Glad to hear you had your brakes fixed.

It seems to me that the water pump is belt-driven by another belt than the
vacuum pump (one belt is driving water pump from the crankshaft, one belt is
driving the vacuum pump from the water pump), so I'd first check the belts'
tension. And I hope you changed it with the vacuum pump (it was time to
change this, for a couple of
dollars).

Second thing to check is the correct fan clutching. Keep in mind it uses a
motor-driven, electromagnetic-clutched fan.

Pretty classic, until you're idling for a long time (and especially in a hot
day), in traffic jams or under heavy load & low speed (typically on a
hillclimb).

HTH,