528 temp guage question - urgent

[digger_R]

I've just picked up an E39 528 and noticed when driving it yesterday after driving for about 25 mins the temp gauge didn't go much over a quarter. If I remember from my old 523 then it sat around the half mark.

Can anyone confirm which is correct. I'm doing an 800 mile run next weekend so would prefer to have it checked out before hand. I vaguely remember something about thermostats and rad hoses but don't have the time to search right now

I'd appreciate some help, thanks

[phelix]

Although it's not quite the weather for needing it how much heat is the car putting out? A temp gauge staying low is often the result of a broken thermostat that's stuck open. Will hurt your fuel economy.

[fluffnik]

The guage is NOT analogue; it should sit dead centre if the temp is in the normal range.

Sounds like a duff thermostat.

[madou]

digger_R said:

If I remember from my old 523 then it sat around the half mark

This is what should happen, just as the other responders have stated

[digger_R]

thanks for all the help turns out i simply didnt run it for long enough last night. It was fine driving around today.

[phelix]

Keep an eye on it; it should reach normal operating temp in about 10 minutes this time of year.

[parksie]

Glad you think all is well, we've been down this route with my boys 528i, changed the Pump/Stat/ & top housing, & Today he phones to tell me whilst sitting in traffic the temp started rising upwards.

So after all these replaced parts ,anyone have ideas why? Fan maybe??

[[TW]Fox]

My 530i never takes more than 5-6 minutes to get up to temperature and the guage rises steadily until it sits in the middle. If its sticking around a quarter the thermostat is defective - not a hard or expensive job.

[sniff petrol]

I had a 306 Dturbo that would take 30-40mins before it would show normal working temperature even though the rad was warm all over as normal. After flusing the cooling system and filling up with new antifreeze it worked fine so I could only imagine the temperature sensor was clogged up with gunk.

[fluffnik]

anonymous said:

[redacted]

Perhaps, but the behaviour isn't.

They don't hang about between 1/4 and 3/4 except at exactly 1/2.

[fluffnik]

anonymous said:

[redacted]

Could be, could be the whole cluster is digitally driven - its self-test routine suggests the latter to me...

[phelix]

correct - the ECU "drives" the temp gauge; there's no direct connection between the sender and the gauge

[digger_R]

Right this has become a bit more confusing. On a long run yesterday, it seems the temp sits at 1/2 when the ambient temp is reasonably warm. Anything cool (driving at night 10 deg) and the temp is way down.
Am I damaging anything by driviing it while this is going on? Is this just likely to be the thermostat?

[sniff petrol]

digger_R said:

Am I damaging anything by driviing it while this is going on? Is this just likely to be the thermostat?

Wouldn't have thought so - just using a bit more fuel so a new thermostat would probably pay for itself in the long run.

[phelix]

digger_R said:

Am I damaging anything by driviing it while this is going on? Is this just likely to be the thermostat?

Not sure it's good for the cat if the engine is over fueling. The oxygen sensor reading will result in the ECU trying to compensate by leaning the mixture but perhaps not enough as it's designed to fine tune the mixture, not make large corrections.