camera doctor 25 Report post Posted September 27, 2011 2003 E39 530i Touring. I've been doing a few highway runs lately and noticed the E39 seems to be running cold on the gauge. Around town it sits slightly left of centre, but once I get on the highway, it falls into cold zone. Last week when the outside temp was 5 Degrees, it ran right into the blue zone. Today at 20 degrees outdoor, it still sat right on the righthand edge of the blue zone. I am guessing it really should be somewhere near centre always ? Thermostat failure ? Thoughts ? Thanks Quote Share this post Link to post Share on other sites
barf 0 Report post Posted September 27, 2011 thermostat failure is the first thing that comes to mind pretty easy to check the sensor with an ohmmeter too. my old E30's thermistor is negative temperature coefficient type. the resistance decreases with an increase in temperature. you can use use a resistor wheel to check the gauge. Deg C Ohms -10.0 9300.0 20.0 2500.0 80.0 335.0 Quote Share this post Link to post Share on other sites
Docile 64 Report post Posted September 27, 2011 that happened to my car thermostat problem. although get your waterpump checked as well while your in there. Quote Share this post Link to post Share on other sites
Steve K-B 51 Report post Posted September 27, 2011 Def the thermostat! Quote Share this post Link to post Share on other sites
allan 295 Report post Posted September 28, 2011 ] Put my head on the block and say that the electric heating component in the housing is failing. Mine was doing the same thing in town temp down a little on gauge but on the highway dropped way down. After replacing the thermostat/ housing combination, water pump with steel impellor, tensioner, idler pulley and new belts it was as quiet as a grave yard under the bonnet and the temperature gauge was back up on 12 o'clock. The idler pulley and tensioner pulley had been getting louder for some time so the whole lot got replaced in one go. If you do this your self be carefully with the little tab that locks the expansion tank/ bleed screw thinge in place they brake off with out to much force, cost me a new fan shroud.The fan is a little fiddle but once you get the fan and shroud out of the way it is easy the fan nut is 32mm and left hand thread, hope that helps Quote Share this post Link to post Share on other sites
camera doctor 25 Report post Posted September 28, 2011 ] If you do this your self be carefully with the little tab that locks the expansion tank/ bleed screw thinge in place they brake off with out to much force, cost me a new fan shroud. Thank Allan, Yep, that shroud got broken by my mechanic at last anti-freeze change -_- It has been glued with Plastic Weld and seems to be holding ... so far !! Do you remember how much the shroud was ? May be worth doing the complete job as you did. Cheers Quote Share this post Link to post Share on other sites
allan 295 Report post Posted September 28, 2011 Hi Greg; The shroud cost $43.50 US when the xchange rate was at 86 something. It came with the pump, thermostat/housing,pulleys, both belts plus a couple of little plastic rivets $425 odd NZ. Got them from Pelican parts even with the freight charge was still cheeper than I could get them here in NZ sorry to say. That must be some good glue as I tried a couple of different types all to no avail. From what I have read that 120,000km mark seems to be when thing in the cooling department start to fall apart. Best of luck in getting it sorted. Allan Quote Share this post Link to post Share on other sites
