N42 gurus

[Higgs boson]

My son's e46, with N42 engine, has a ropey thermostat. Or the sensor that tells it to open is fubared.
Does anyone know where the sensor is?
Thanks.

[Easternlight]

Thermostat doesn't have a separate sensor it works off a wax capsule within it.
It's the bit they call a charge cylinder in this photo.
https://i.stack.imgur.com/ECgZO.jpg

[Higgs boson]

Thanks for the reply, but I've got to ask ... have you had sight of the thermostat of which I speak?

[Fas1975]

Check this diagram

http://www.realoem.com/bmw/enUS/showparts?id=AY72-...

There's a pipe marked number 8, it leads to the thermostat. This was just a quick search so haven't looked for the thermostat itself, but this should guide you a little.

[Higgs boson]

Thanks for the reply, but realoem doesn't help much in this case.

The thermostat looks like this ...

[helix402]

Put "N42 thermostat replacement" into Google and lots of info comes up.

[Higgs boson]

Aww, come on now Helix, you know that's the first thing that I'd have done, don't you?
Well, actually, that's not true. I consulted realoem first, then Google. Then I thought, as, unexpectedly, they were of no bloody use, I'd try the brain trust.
It now seems that even the wisdom of PH can't shed any light on the issue.

[iSore]

The stat is conveniently* bolted to the side of the water pump, which itself is conveniently* bolted to the front of the PAS pump down in the bowels of the engine bay on the exhaust side of the block. As long as the tiny tore bolts come undone, they're not too bad - if they round off, a hammer and a long sharp screwdriver to break it up in situ and you'll need the plastic housing it bolts to as well. Like everything else on this engine, it would appear to have been designed by a maniac.

[helix402]

A rather good description of the N42. It was also built near Birmingham. (Hams Hall).

[Higgs boson]

iSore, thank you. I know where it is. I've changed the waterpump I the past.
Now, back to the original question ...
Does anyone know what controls the power supply that "tells" the thermostat to open?

[helix402]

The engine ecu controls the thermostat electrical side.

[Higgs boson]

helix, on the basis that you're not being deliberately obtuse, do you know what sensor tells the ecu to do that?

[helix402]

This may help: (different engine same theory)

http://www.meeknet.co.uk/e38/E38_Map_Thermostat.pd...

The engine ecu (DME) will probably also evaluate the engine/rad temp from a few other sources, such as: coolant temp sensor on cylinder head, radiator outlet temp sensor. You may be interested to know how the electric cooling fan works, 3 wires, +ve, -ve and a pulse width modulated signal from the DME.

Hope this helps, no obtuseness intended, I've forgotten all my trigonometry!

[Higgs boson]

helix402 said:

Hope this helps, no obtuseness intended, I've forgotten all my trigonometry!