Z3 overheating.

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Pele no2
Joined: Tue 20 Feb, 2018 21:21
Posts: 2

  Z3 roadster 1.9i

Z3 overheating.

Post by Pele no2 » Sun 11 Nov, 2018 18:55

Hi,I’ve had my 2001 1900 z3 sport for approx 4 years. About 2 years ago it was taken out for the day, ran faultless until we met some slow traffic a few miles from home when I noticed the temp gauge in the red. I stopped, but in the end got towed home. I ran it to my local garage, whom put a new water pump, complete housing and a new belt etc, ran it for 4 hours on tickover and reported no problems. I took the car out last weekend for about 30 miles and within a couple of minutes of slow traffic it had overheated again, temp in the red.
I lifted the bonnet but I’ve never heard or seen the fan come on. I checked the radiator after slowly taking the cap off and it was full. Left it 30 mins then set off back home, all fine when running at speed. Got back home, checked the radiator and it was only about a third full, so I topped it up with anti freeze.
I have relocated so not sure where to take the car. I would like to do some basic checks before I send it in, can anybody give me some pointers, as it’s not easy to get under the car or get to the stuff under the bonnet as it all seems a bit tight to me.
Is the radiator at fault?
Thanks, Mark.

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colb
Joined: Sat 05 May, 2012 23:46
Posts: 646

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Z3 overheating.

Post by colb » Sun 11 Nov, 2018 19:06

Sounds like you have a leak when the system is hot and under pressure and loosing the coolant. Top the car up and run it up to temp then look at all rubber pipes and radiator for leaks. Check the footwell carpets to see if the heater matrix has sprung a leak. Your previous experience of overheating where the garage put in a new water pump may well point to a new leak in the system having developed. A garage could do a pressure test but you will end up paying for that to be done. If the car was running ok lets hope the head gasket hasn't blown.
When you run it up to temp check the fan comes on, if it fails to cut in then test that with 12v connected to the fan to see if it is working, if it spins up then suspect the temp switch that controls it.
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

Pele no2
Joined: Tue 20 Feb, 2018 21:21
Posts: 2

  Z3 roadster 1.9i

Re: Z3 overheating.

Post by Pele no2 » Sun 11 Nov, 2018 20:04

Ok, that’s great. I’m wondering if the temperature switch may be faulty then. Is this a simple thing to replace?
It doesn’t seem to leak water anywhere when parked up. I wondered if there was some kind of blockage maybe in the radiator due to the age of it also, so it’s not circulating.
I think I need to check the fan first job.
Should the car get that hot after being in traffic only for a few minutes?

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colb
Joined: Sat 05 May, 2012 23:46
Posts: 646

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Z3 overheating.

Post by colb » Sun 11 Nov, 2018 21:15

Getting hot quick in slow traffic should be regulated by the fan cutting in, will come in dependant on water temp and outside temp will also be a factor. Hot day and slow traffic will cause the temp to rise until it triggers the fan to come on. As soon as temp reduces the fan will cut off until the temp rises again to bring it back on again. Temp sensor is a screw in sensor on the radiator if your putting a new one in do it with engine cold and have new one to put in quick so you do't loose coolant.
The temp guage should be at the middle position 12 o'clock on the guage when up to temp usually stays rock steady at that position if it climbs the fan cutting in should bring it back down to the centre position. If you suspect a blockage then you will need to flush the system out using a hosepipe and back wash it. When refilling get the front of the car high as possible in order to get all the air out of the system.
We havn't mentioned the possibility of a faulty thermostat having failed in the closed position, if it has then that could be a cause of overheating. Only way of checking that is take it out and put a new one in.
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

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sirius-c
Joined: Wed 12 Dec, 2012 22:24
Posts: 496

  Z3 roadster 2.8
Location: Eeh ba gum lad, 'ow do?

Re: Z3 overheating.

Post by sirius-c » Mon 12 Nov, 2018 14:58

Have you checked the thermostat?
It sounds like this is the guilty one to me
1997 2.8L Z3 Roadster

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Designed or not designed, that is the question.

Boosh
Joined: Sun 30 Nov, 2014 22:40
Posts: 317

  Z3 roadster 1.9i

Re: Z3 overheating.

Post by Boosh » Wed 14 Nov, 2018 08:20

Hi,
In my experience, the over-heating and consequent head gasket blowing was due to a faulty Relay not triggering the fan. Expensive repair (new engine) for a cheap part!
Fingers crossed you caught it in time...

Boosh.

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dazthephot
Joined: Wed 09 Apr, 2008 19:58
Posts: 159

  Z3 roadster 1.9i
Contact:

Re: Z3 overheating.

Post by dazthephot » Wed 14 Nov, 2018 21:16

Just to add my two Penneth. I had a similar issue which resulted in a week long investigation, replacement of the thermostat, water pump, radiator then eventually the head gasket. The first big thing I had to pay for after only 2 years of ownership.
Turns out the original fault was a blocked radiator and BMW couldn’t find it until after they’d replaced everything.
Thankfully another 10 years down the line the car is still running pretty sweet.

You could try a rad flush or even replacement??? I don’t know how to test for a blocked radiator.


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