can you tell me why my volvo 740 overheating?

you probably need a new radiator.
However, a neat trick for pin holes is to put a tablespoon of white pepper (yes pepper ... ah choo) in the radiator water.
It worked for me, and been like that for 12 months or more.

Ted

Ted
July 2007

OVERHEATING CAN BE FROM LOTS OF THINGS,
PROBABLY YOUR THERMOSTAT IS STICKING.
THERE SHOULDNT BE A HOLE LEAKING WATER.
SURE IT ISNT A HOSE ? IF IT ISNT THE THERMOSTAT THEN ITS A WATER PUMP / FAULTY TIMING /CLOGGED UP EXHAUST / BAD COOLING FAN OR COOLING FAN RELAY IS BAD / THE RELAY ALSO GETS A TEMPERATURE READING FROM A SENSOR IN THE ENGINE. IF IT ISNT WORKING
THE FAN WONT COME ON AND COOL THE RADIATOR.
YOU WILL PROBABLY NEED A MECHANIC, OR SOME MORE ASSISTANCE TO FIGURE THAT OUT.

JESSE P NELSON
June 2007