Over heating

[borischatting]

I just bought a 1991 Volvo 410 GLE with a 1721cc engine.

The engine starts overheating if I'm driving really slowly or stuck in traffic.

Highway driving is no issue. I have not found any leaks on the ground and the coolant level is fine. The fan does not start when I start the engine but turns on when the temperature is close to the red and stays on after I've turned the engine off if it's too hot.

If anyone can help or give me an idea of what it is it would be greatly appreciated.

[GTMaster]

It's alright for the fan to turn on when the engine is hot. It happens often in summer and when driving slowly in traffic. If the fan turns on and the coolant temp goes down then everything is fine. It's normal. The fan keeps going after the engine has been turned off, because an electric water pump keeps circulating the coolant after the engine has been shut off and the temp is at i think above 86 deg. It works for around 5 mins but no longer for 20 mins.

[grass hopper]

could be a faulty thermostat,if not opening there will be poor coolant flow to the fan sensor in the radiator so it will come on late or not at all,to check,run the car until the fan cuts in and feel the top hose and top of the radiator **it will be close to boiling point so be careful** then have a feel at the bottom of the radiator and the bottom hose they should be a lot cooler,this is normal with a good thermostat,if the radiator and both hoses are fairly cool and the same temp then its jammed shut.

thermostats are cheap so i would just put a new one in and try.

another possability is the gauge reading wrong,had this on a few were the gauge and circuit board req replacing. GH

[Georgey dee]

You could try taking the thermostat out and seeing if things improve. I would replace it though as your car will suffer in the winter without one.

I think they're about £15 from the dealer

[narc]

Radiator may be blocked with 19 years accumulated muck. Try the thermostat first as its easier, (you can check it by heating it in a pot of water it should open before the water boils, alternatively just change it anyway).If the car still runs too hot take off the radiator and back flush it with your garden hose which may work, sometimes the core can be so gunged up that this will not work and you need either proffessional help or a new radiator core.

Good Luck.

Ian

[jeff t]

My guess is it might be the temp guage as a lot seem to suffer this I have had my 460 (1992) from nealy new and had the same problem twice and both times it has been the temp guage , or shall I say the temp pcb.
The pcb is held apart from the guage by 4 brass spacers which seem to cause like corrosion with the pcb causing the gauge not to work properly.

[ahal]

Originally Posted by narc

Radiator may be blocked with 19 years accumulated muck. Try the thermostat first as its easier, (you can check it by heating it in a pot of water it should open before the water boils, alternatively just change it anyway).If the car still runs too hot take off the radiator and back flush it with your garden hose which may work, sometimes the core can be so gunged up that this will not work and you need either proffessional help or a new radiator core.

Good Luck.

Ian

Quite agreed. I did this with mine ( 1994 440 ) and you'd be amazed at what comes out of the radiator. The older 400's are known for running hot anyway. My old 460 ( also 1991 ) did exactly what you describe as well, though I never drove it long enough to get to the bottom of the problem. If the car has lain idle for a long period I'd particularly suspect the thermostat. I've also noticed that temp. gauges suffer badly from the car not being used.

The only other thing I can think of is that there might be an airlock in the cooling system? There should be a bleed screw in the engine bay, somewhere under the windscreen.

Good luck,

Tony