Overheating issues, fan not coming on

Turbomick1985 · Post by **Turbomick1985** » Sun Aug 25, 2013 3:02 pm

Just got my car back from mechanics where it had a service and got brakes, calipers and pads done after some messing around, picked the car up Saturday after the garage closed and drove my girlfriends to her friends wasn't driving hard or anything and noticed the car was running quite hot, it was at the three quarters mark on the temperature gauge so I turned on the heaters in the car and it cooled down straight away ( old trick my grandfather told me for old cars that get hot) anyway drove home and when I was on the a12 and the a406 it didn't overheat, got into my driveway and the temperature gauge went up, I opened up the bonnet and neither of the fans were running, turned off the car and went through the basics
Check the water level it was fine
Checked the connections in the engine that I could i see around the rad and none were loose
Checked the fuses they were fine
Checked the relay for the cooling fan but it wasn't corroded and I didn't know what else to look for

I think the rad motor might be knackered, I'm a bit pissed off because the garage had the car a week and it didnt have this problem going into the garage

Is it a simple fix to swap the fan for a new one or do I have to swap the whole thing?

Any help much appreciated

Post by **vanzep** » Sun Aug 25, 2013 3:08 pm

could be an air lock in the coolant system - you can bleed this by opening the coolant valve ontop of the thermostat and let coolant out of oit until there are no bubbles in it and a steady stream of coolant - 10mm spanner (or 12mm

) should be all you need

bb1boy · Post by **bb1boy** » Sun Aug 25, 2013 3:11 pm

Also you can test the fan by putting 12v straight to it, if it spins then the motor is ok. Like Vanzep said, try to clear any trapped air first. The fan should come on before your temperature gauge gets to three quarters hot.

Turbomick1985 · Post by **Turbomick1985** » Sun Aug 25, 2013 3:15 pm

Sorry to sound like a mechanical related but there would I find that mate I have a few spanners to do it, should the car be running when I do this?

Post by **vanzep** » Sun Aug 25, 2013 3:21 pm

im sure @Merlin did a write up on this - it should be in the wiki section under 4th gen thermostat/cooling

Post by **vanzep** » Sun Aug 25, 2013 3:24 pm

http://www.ludegeneration.co.uk/post14248.html#p14248
found it - heres the location of it - its a bleed bolt so has a hole in the end of it for the coolant to drain out of - you just need toloosen it when the engine is idling - take the rad capoff first and make sure the coolant is filled to the top put the cap back on start the engine , loosen the bolt until coolant comes out - let any bubbles and air come through and then tighten it back up once you get a steady stream of coolant running out - mop up any spilt coolant and thats it.

Turbomick1985 · Post by **Turbomick1985** » Sun Aug 25, 2013 4:06 pm

Ok so I did that and a few bubbles came out only for a second or two then ther was no bubbles, I took the car for a quick drive and just as I pulled back into the drive it was creeping past Half way mark, i repeated the process but when I did it this time I opened the bleed valve a bit too much and it shot out so I couldn't tell you if there was any bubbles, the rad fan still isn't coming on either

bb1boy · Post by **bb1boy** » Sun Aug 25, 2013 4:36 pm

It takes ages for the rad fan to come on mate, I thought mine was broken but it turned out I was just being impatient. You could do with testing your thermostat and the thermo fan switch really mate, but if you haven't done it before you may need some help. Do any fellow 'Luders live near you?

Turbomick1985 · Post by **Turbomick1985** » Sun Aug 25, 2013 4:44 pm

I've taking off the switch for the fans off the thermostat and stuck some copper wire in there turned on the ignition and both fans came on, so I'm guessing the relay is ok and the fans are ok, I'm guessing it's the thermostat or the switch, I think I can take off the switch but I don't know what to look for to know if its knackers, i put a thread asking for anyone who knows a mechanic or is mechanically inclined a few weeks ago but no takers

Post by **vanzep** » Sun Aug 25, 2013 6:35 pm

could be your thermostat - from my experience preludes dont like being sat around - you might want to get a new thermostat get one thats supplied with the rubber gasket should be around £15for an aftermarket one from the likes of BGA which you can get off ebay. drain your coolant - take out the the old thermostat - fill it up and bleed the system - you might want to flush out the rad whilst your at it. My lude took a while to setle down after id replaced the rad and stuff . The only other easy thing to check for is the seal on the rad cap make sure its not split or perished - again an easy cheap fix if it needs replaced.