Overheating?

[lukeb]

Ok iv'e got a bit of a wierd problem with my cooling. The needle has started to rise into the red when in slow moving traffic (-30mph) or when at a stand still. but as soon as i start moving, and after literally 30 seconds the needle comes back to half way. However it doesn't slowly come back the needle just jumps back to half way. Iv'e checked the pipes several times when the needle has been in the red and there not hard at all, just firm as they should be. And the fan spins all the time.
My dials work intermitently anyway (fuel gauge and tacho) and i know i should change this first to take a faulty gauge out of the equation, but i was wondering if there is anything else i can do to determain if my car is overheating or not?

Any help would be appreciated

cheers

[E30BeemerLad]

with the car upto temperature and with it running, lift the bonnet and stick a rolled up newspaper into the fan blades, if it stops the fan when the car is hot, then the viscous clutch on the fan is knackered.

As the car cools down when you are on the move it suggests air is not passing through the rad when stationary, hence check the fan.

Would also check to see if the thermostat is working.

Feel the coolant pipes near the top of the rad and then feel the bottom ones, if the bottom ones are cooler then the thermostat isn't opening.

Sometimes it can be a good idea to take the rad out and stick a hosepipe into it to flush out any crap in there.

Should get you sorted I hope. Don't let it cook itself though, especially if it is a 6-pot, that will only lead to cracked head in due course.

[lukeb]

Its only a 4 pot unfortunalty, i will try your sugestions later today, well in an hour or so, just wont be able to take the radiator out but hopefully i wont have to, not a hard job though. will let you know how i get on.

cheers dude

[lukeb]

ive done what you said and the fan stopped spinning the hoses from the radiator are at the same temperature so i think the thermostat is ok.

so if the fan clutch is nackard, is it a hard job to replace it? and do you know if its a sort of part they would have at GSF or is it easiest to get one of here?

[mrLEE30]

easy to replace but you will need a 32mm open ended spanner and a soft hammer. and dont forget the thread that holds the viscous clutch on is opposite thread so you loosen to tighten!!!

use the hammer to hit the spanner until the nut loosens (while yer mate holds the fan)

mrlee

[E30BeemerLad]

viscous is easily obtainable from gsf mate, it's an easy job so long as the 32mm nut (left hand thread) will come undone on the shaft, simple swap over and away you go.

I have a spare good condition one, but not sure if there is a risk that the fluid will leak from the clutch if it is posted, so you are best buying new, don't think they are that much anyway, so try www.gsfcarparts.co.uk or eurocarparts.

[lukeb]

on gsf i cant find the part on the site. it comes up with fan coupling. is this it?

[E30BeemerLad]

yes I believe so mate

look on www.realoem.com and you will find the part/ description too

[lukeb]

sweet cheers dude

will get a new one tomorow.

[lukeb]

i fitted a new fan clutch and its still overheating. are the only other possibilities thermostat and radiator?

[RogerS]

Hi Luke,
Have the same problem on my 325, had the beastie back 4 times, had a changed rad, rebuilt compressor, changed the thermostat, checked the fan, pressure tested the system twice, checked for head gasket problems and all they can find is a faulty gauge.
When driving it sits on half then slowly creeps up, then drops down to half suddenly.
If I bang the dash with my hand when it is in the red it drops down to half also.
The other funny thing is when I reverse down the drive to swop cars over, it flicks into the red.
Cheers,
Roger

[lukeb]

yeah thats pretty much the same as mine. There have been a few times ive started the car in the morning and its already in the red, a little tap soon sorts it out though.
Ill have a look over the weekend and if i dont find a problem it must just be the gauge. i think thermostat is ok from what "E30beemerlad" says, so ill flush out the rad, do a compresion test to see if head gasket is ok then i dont think there is any more to do?

[lukeb]

well i flushed the system out today and put in new coolant, and it seems to have done the trick. Ive only drove it from picking up the miss's but the gauge never even got up to half way even in traffic.
Can anyone tell me why changing the fluid makes such a big difference. Am i right in thinking that because the coolant is old and shitty (it was black) that it just wasn't working (cooling) as it would if it was new. But just dont understand why?

Silly question just interested.

[E30Adam]

Coolant only lasts about a year or two, after this is deteriorates and has little affect on cooling.

If it was black then it was definately in need of changing. I hope you flushed your system through before refilling with fresh.