Coolant Temperature Senser, 1987 Volvo 240 SW

carlpop · Post by **carlpop** » 29 Oct 2007, 14:58

I recently purchased this car here in Phoenix but will be leaving it in a cold winter climate. Although it runs well in Phoenix, naturally I am concerned about cold weather starting. The temperature gage does not work and I notice that there is a coolant temperature senser in the radiator without a wiring harness connected to it; I can not find the harness. Does this temperature senser affect cold weather starts? Where is the harness? THX!

Post by **billofdurham** » 29 Oct 2007, 16:33

Welcome to Matthew's Volvo Site.

The coolant temperature sensor is not in the radiator. It is on the left side of the engine on the intake manifold.

The only switch I can think of on the radiator is for the thermostatically controlled cooling fan, if one is fitted.

Not all 240s had this type of fan. Some were fitted with a viscous coupling fan. Check to see what type of fan you have. If it is thermostatic then you will need to locate the wiring. If it is viscous it is possible that the radiator has been changed at some time.

Bill.

carlpop · Post by **carlpop** » 29 Oct 2007, 17:03

Thanks...this makes perfect sense...I have a viscous coupling and the radiator does look recent. OK...so the temperature gage is not working. What is the most common reason for that and would you expect it to affect the engine control unit logic and/or cold starts?

Post by **billofdurham** » 29 Oct 2007, 17:35

The most common faults are the wire has come off the sender or the sender is faulty.

If the sender is faulty it is a straightforward replacement. The only test I know is to remove the wire, switch on the ignition without starting the engine and touch the wire to earth (ground). Have someone in the car to see if the gauge registers.

A faulty sender will affect the running but not the cold starting.

Bill.

wojeepster · Post by **wojeepster** » 29 Oct 2007, 21:31

There are two temperature senders. One for the gage and one for the ecu.

carlpop · Post by **carlpop** » 30 Oct 2007, 11:03

Would you please tell me where each temperature sensor is and which is which? THX!

Post by **billofdurham** » 30 Oct 2007, 13:46

The sensor that controls the gauge is on the inlet manifold. The other sensor does not affect the gauge. Its purpose is to pass information to the engine control system which adjusts timing etc, dependant on coolant temperature.

Bill.