overheating M42

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DHFiS
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Post Mon Oct 13, 2014 8:17 am

My car has been running a little over its normal temp for a while but yesterday I had to stop as it was getting near the red. I have also noticed the heater doesnt blow hot air.

Both pipes to the rad are hot.

Does it sound like the water pump has stopped working?
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BHadley
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Post Wed Oct 15, 2014 11:16 pm

Does being in traffic affect the temp reading?
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ajay
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Post Wed Oct 15, 2014 11:28 pm

As above, check the fan clutch.. If thats not the culprit to the high temp read below!
I had the exact same symptoms with our 318is, it turned out the heater matrix was shagged, (replaced for new) and the heat was back on, and the temp gauge or temp switch had a poor connection which resulted in the high temp reading, ( temp switch connector and temp gauge terminal nuts cleaned and refitted) and all was back to normal.
I'm not saying yours will be the same but you can also check your heater valve, ( this could stop the heater working) and test the water temp switch and connections as above and check the rad is in good order, with a bit of luck you should get to the bottom of it, failing all that it could b an indicator of head gasket troubles, ( im sure there are more qualified zoners to explain these symptoms) and checks you can do!
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BHadley
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Post Thu Oct 16, 2014 12:21 am

Is it loosing any water/coolant ?

Any "mayonnaise" looking gunk in the oil cap or on dipstick?

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DHFiS
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Post Thu Oct 16, 2014 8:56 pm

I did the newspaper test on the fan and it looks like the viscous coupling has failed but this doesnt explain the heater not blowing hot.

Not losing water and no mayo.
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BHadley
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Post Thu Oct 16, 2014 9:33 pm

Any service history of a water pump change or thermostat coolant change etc?

They can be overlooked as the engine is timing chain not timing belt, as the chain lasts longer the pump etc gets overlooked.

Eg; my m42 has 200k when I changed a noisey water pump it still had 1989 stamped in as a date code!

Two hot hoses make it sound like poor circulation so I'd change water pump, thermostat and reverse flush the rad. Doing this and a decent coolant change will help the heating side of things by bleeding the system.

Euro car parts or car parts for less prices are always good, have found GSF pricey in comparesion