Fluctuating E30 temp gauge

[Kepes 231]

Hey team

I replaced the head gasket on my 1987 325i, and had a hard time getting the fan clutch off of the water pump, and so i went at it with a hacksaw and replaced the water pump with a brand new one, and for the fan clutch I used a second hand one (not 'known' working but cheap).
The temp needle would rise to over 1/2 in traffic or slow driving and so I replaced the fan clutch, again with a second hand one from Andy, which has around 130kms on it IIRC. Thought it would solve the problem, but it hasn't. Andy mentioned it had been sitting for around 9months - could it possibly be that it just needs to be worn in again?

Before doing the head gasket, I had no problems with temp. Radiator is fairly new, t/stat is 1 year old, new w/pump, coolant temp sensor(blue sensor) is 6months old, coolant is fresh, system is bled of air, and no coolant leaks or oil/coolant mixing etc.

Most probably is the fan clutch, but I wanted to know if anybody had other ideas before buying a new one for ~$200. (done with 2nd hand!!) After doing a little research some people say that it could be a loose nut on the back of the gauge, but what i'm seeing is too consistent for that to be the case I think. Could it possibly be that the coolant temp sender(brown sensor) is faulty?

Thanks for any help!

Edited January 9, 2015 by Kepes

[hotwire 352]

Was the radiator flushed/checked for blockage?

Common denominator to what sequence you have described is the fan hub - both are different to the original (to which you said had no issue)

Replace it with a new one!

To confirm gauge accuracy - you need to confirm whether the coolant is infact hot - what temp is it getting to when the gauge reads high?

[Young Thrash Driver 1020]

As above, I'd make absolutely certain the radiator isn't blocked. My car was displaying your symptoms and 10 min of running the garden hose through the radiator and the engine block fixed it.

BTW, "so i went at it with a hacksaw" is just f**king awesome haha

[_ethrty-Andy_ 2132]

brand new radiator would be a better investment than a brand new viscous hub anyways, and not that much more anyways iirc

[Kepes 231]

Thanks for the suggestions guys. However radiator doesn't look very old, and prior to changing the fan clutch I had no problems with the temp needle moving. I just find it hard to believe that 2 fan clutches could be bad?!

Drove north today and got stuck in traffic :-( Tried to find an alternative route/back roads but just spent 20mins wondering. Needless to say I ended up with the heater on full blast in 24 degree heat . In my frustration I bought a new fan clutch as soon as I got home. Let's hope it's all good once that goes in!!

BTW, "so i went at it with a hacksaw" is just f**king awesome haha

hahah after trying to get it to budge after 1 day of heating it, wd40ing it, making up a fan clutch holding tool etc etc I was pretty furious. Job well done nonetheless

[Allanw 1071]

brand new radiator would be a better investment than a brand new viscous hub anyways, and not that much more anyways iirc

I agree - Dads E30 is on it's 3rd radiator, and original viscous coupling. The gauge never moves.

Dad replaces the radiator before it causes trouble (if it looks a bit average, a new one goes in), but the Viscous coupling has never been as issue, though he never sits in traffic for long, just the "rush 20 minutes" if they're going somewhere at everyone elses home time.

[Kepes 231]

If the problem persists I will look into getting a new radiator. What is the best option for getting one of those? eg. would buying one locally from a radiator shop be better, or from the dealership, or from pelican parts etc?

[hotwire 352]

^^^ Get it checked by a radiator repairer. No point in replacing on a whim.