No idea what is wrong with my car

Hi Guys,

3 week's ago I noticed that my best in the world car has problem with overheating. The symptoms were strange as car heated up to ¾ of temperature scale and after couple seconds came back to normal. So I went to mechanic and he told me that there is problem with viscotic fan clutch and this should be replaced as a first. Just in case I have also replaced water pump and v-ribbed belts. I collected car last Sunday and for about 2 hours everything was ok then after car started heat up again. I rang mechanic and explained what happened then he advice me to open valve on rubber pipe as maybe some air in the cooling system. I did it and symptoms gone. Then again today was driving for about 2 hours and problem came back. What's wrong with this car. It doesn't overheat straight away but after couple hours. Mechanic said that thermostat is working properly and he tested car before I collected but he never drove this car. Just tested in garage. Any idea?

Thanks.
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Forgot to mention. My car is e46 320i m54 engine.

Have you checked your waterpump? Impeller may be falling into pieces and not moving coolant properly.


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Edit. Never mind. Didn't read your post properly. Waterpump was changed.

Do a compression test. Headgasket may be gone. M54 engines don't like overheating at all.

As I said. Water pump is brand new, fitted together with visco fan.

Viscotic fan starting immediately after switching on engine for about 20-30 seconds. After that never heard to be working again.

What viscous fan did you use they dont like aftermarket ones at all

Full cooling system should be replaced anyway its first job for an m54

It's not OEM but have been told is good German product (VEMO)

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Originally Posted by strefabrzmienia

It's not OEM but have been told is good German product (VEMO)

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Yeh vemo is a good make , iv just heard people non stop complaining about aftermarket viscous fans if possible (I know it's a pain) but if you could get an original one from a breaker or scrapyard to try at least it would cross it off the list
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Also just noticed there you siad when you bled it it went back down its possible you still have air in the system

I will try it then. Thanks Gar.

No problem we have good mechanics on here so maybe they will help you diagnose it when they see your post its very hard to diagnose correctly without seeing the car though

This is a way I tried remove air from cooling system. Front of car up, heating inside turned to 32 degrees and unscrew vent on rubber pipe. Done it at least 3 times with no effect.

Sounds like your doing it correctly so , and whats the coolant level like ?

viscous fan not working perfect on hot , AC fan should kick in if it start overheat as well,but if thermostat opens too late,opens not fully or doesnt open at all ,fan might not work as well . or u already have problem with head gasket .need to fill up cooling system properly and heat it up and see how all these things work .

Looks like something get stuck after while of driving. AC fan working properly. I didn't notice any coolant leak. There was small amount of coolant missing but I guess this happens because too many times tried to get air out of the cooling system.

There is one more weird thing. When set heating up to 32 degrees, engine temperature going back to normal. Every time I'm doing this temperature is ok.

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Originally Posted by strefabrzmienia

There is one more weird thing. When set heating up to 32 degrees, engine temperature going back to normal. Every time I'm doing this temperature is ok.

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Sounds like a shot thermostat.

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Originally Posted by Dave

Quote:

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Originally Posted by strefabrzmienia

There is one more weird thing. When set heating up to 32 degrees, engine temperature going back to normal. Every time I'm doing this temperature is ok.

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Sounds like a shot thermostat.

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^^^ +1

Ordered an OEM thermostat from autohaus. It's second hand part. Will see how it works. Currently driving with heating temperature set to 32 degrees and no overheating at all.

second hand thermostat??

Spent already nearly 2k on this car within 2 months. Brand new cost around 120. Second hand get for 20-30. If this is problem then will buy brand new OEM in future.

M54 thermostat cost from 50e to 80e ,second hand ones 50% are not working straight away or fails very soon after they where wasnt used for a while . even now ,U not sure that its thermostat fault and U still spend cash

Not sure if that is thermostat fault as been told many times is something else. Maybe you are right to get new one. Cheers.

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Originally Posted by strefabrzmienia

Not sure if that is thermostat fault as been told many times is something else. Maybe you are right to get new one. Cheers.

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What you are describing are classic symptoms of a shot thermostat stuck closed.

Just replaced today thermostat with brand new BEHR. Everything works perfect so far. Thanks for help.