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coolant temperature sensor

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gnrsoul View Drop Down
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    Posted: 21-May-2009 at 17:54

my idle speed revs and drops on its own and im getting a bit of over heating? i was told to change the coolant temperature sensor but dont know how to do this it looks like its on the left hand side of the engine block?

any help would be great or any other surgestions of what the problem could be

thanks

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Andrew Rolland View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Andrew Rolland Quote  Post ReplyReply Direct Link To This Post Posted: 21-May-2009 at 18:30

Just cos the car is saying it is overheating that doesn't mean that the temp sensor is faulty, it's more likely to me that something else is wrong.

If you are getting overheating I would start with replacing the thermostat. 

What engine/model/age is it?  The M52 engines (one of many fitted with this waterpump) suffer from broken plastic waterpumps.  This causes overheating. 

Overheating may cause the revs to fluctuate.

HTH

Andrew

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gnrsoul View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gnrsoul Quote  Post ReplyReply Direct Link To This Post Posted: 21-May-2009 at 18:37

its a 1989 316i e30 m40 engine

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Andrew Rolland Quote  Post ReplyReply Direct Link To This Post Posted: 22-May-2009 at 12:39
Originally posted by gnrsoul gnrsoul wrote:

its a 1989 316i e30 m40 engine

Um I have no knowledge of this engine I'm afraid, although it would be still worthwhile checking out the cooling system for obvious signs of distress. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Fushion Julz Quote  Post ReplyReply Direct Link To This Post Posted: 22-May-2009 at 13:00
Is the water boiling in the expansion tank or escaping as steam?
If so, your car is definitely overheating...

If this happens only when idling, check the viscous fan coupling and replace if necesary

If it happens all the time, then it could be the water pump (worn impeller), the thermostat stuck closed or the radiator blocked. It may also be related to a failed head gasket.

If the water in the tank isn't boiling and you are sure the car isn't really overheating, then you may want to test the brown sender and the wiring to it.
The part is No 13 on here



There may also be a poor earth on the back of the instrument cluster that causes the gauge to read maximum....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gnrsoul Quote  Post ReplyReply Direct Link To This Post Posted: 22-May-2009 at 23:33
i just flushed the coolent and put new stuff in the over heating problem is now gone but still a bit of a idle problem when the car is idleing it sit below 1000 rpm then it revs to 1000 rpm on its own about every couple of minutes do you think this is to do with the idle control valve?
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