BMW 520 overheating

V8_EATR · Post by **V8_EATR** » Fri Jun 29, 2007 10:21 pm

I have no idea where to go next! :oops: My wife's 520 has been overheating speratically. I have changed a range of parts from the radiator hoses to the heater core and the thermostat, still no progress. I have used sealant for all of the seals and flushed and serviced the radiator countless times. I feel like I am at a deadend, does anyone have any experiance with 520's? I am lost as of now. Any suggestions are welcome!!!

Post by **Ben** » Sat Jun 30, 2007 8:15 am

When you fill it up do you make sure there is no air in the system - my golf was overheating and part of the problem is the way you are supposed to add coolant - i.e. put some in - leave the cap off - get it to temp and top up as you go ....

Plus, is the fan cutting in when it should?.

Fast Eddy · Post by **Fast Eddy** » Sat Jun 30, 2007 8:27 am

Yes i agree with Ben, try for air locks.
Just a couple of other ideas. Is the water pump doing its job and is the system holding pressure via the rad cap and expansion bottle cap as i have found this to be a common problem that people do not realise.
Good Luck
Eddy

V8_EATR · Post by **V8_EATR** » Sat Jun 30, 2007 8:48 am

Ben, I took your advise and went outside to check out the fan, and sure enough, the fan isn't coming on at all on idle! It cuts in at around 2,000RPM. Anyone know where I can get a fan and maybe fitment? Thanks for the advise, at least I only embarassed myself on this one.

Post by **Ben** » Sat Jun 30, 2007 9:02 am

Sounds like the fan is a viscous one - i.e. on my car it's driven straight from the engine and when temp is up the coupling adjusts and allows the fan to spin ... so you wouldn't expect it to spin immediately ..

if however it's an electrical one then it's down to the temp sensor ...

Anyway bryan can't you just pretend it's an F15 and get your crew to fix it

mirage · Post by **mirage** » Sat Jun 30, 2007 9:31 am

if it turns out not to be the fan try getting a new radiator cap, i had same trouble as you with the skyline new cap sorted it as it wasnt holding pressure.

V8_EATR · Post by **V8_EATR** » Sat Jun 30, 2007 1:51 pm

murano3 wrote:
Anyway bryan can't you just pretend it's an F15 and get your crew to fix it

LOL, I've already tried that :lol:

John, I will start with the cap first then, sounds like a cheap first step, then on to the temp sensor.....ahhhhhhhh electricals!

Thanks guys, I'll keep you posted on the progress.

This is the devil itself, not bad to look at, but thats about it!

http://s71.photobucket.com/albums/i134/ ... s002-1.jpg

Ian200sx · Post by **Ian200sx** » Sun Jul 01, 2007 5:23 pm

Does it have a bleed screw on the rad (next to the cap) I'd say air lock.

steveVR6 · Post by **steveVR6** » Sun Jul 01, 2007 6:54 pm

I had the same type of problem with my VW. It turned out to be the rubber seal in the rad cap. A quick and simple fix...

V8_EATR · Post by **V8_EATR** » Sun Jul 01, 2007 8:28 pm

Ian200sx wrote:Does it have a bleed screw on the rad (next to the cap) I'd say air lock.

Does have a bleed screw, but no hissing or air bubbles when the car is on or right after I turn it off.