Coolant sensor location Z3 1.9i

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LMMarks
Joined: Fri 03 Jun, 2016 17:24
Posts: 12

  Z3 roadster 1.9i

Coolant sensor location Z3 1.9i

Post by LMMarks »

Evening all,

Firstly, sorry if this is in an inappropriate place... I wasn't too sure where to post.

Also, sorry, bit of a noob post... I am trying to identify my engine coolant temperature sensor having identified it as faulty (I assume this is the sensor attached to the dial on the dashboard). I have the Z3 1.9i 4 cylinder M43B19 engine (facelift model, see http://i.ebayimg.com/images/i/221603593 ... -l1000.jpg). The board attachment quota has been reached or I'd have uploaded a picture. Whilst there is an excellent tutorial by pelican parts on swapping this part out for the (I believe) pre-facelift model, the sensor is clearly in a completely different place on mine (not behind the bracket as the tutorial says). The front of the cylinder head has various connections into the thermostat/other but I'm unclear which will be what I'm after. Also I'm hesitant about the condition of some of these plastic tubes and electrical connectors and would hate to unnecessarily damage something in the process of this replacement.

If someone could possibly explain where I'm looking, that would be very kind!

Kind regards,

Laurence
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colb
Joined: Sat 05 May, 2012 22:46
Posts: 690

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Coolant sensor location Z3 1.9i

Post by colb »

Looking into engine bay temp sensor is on left side of radiator
http://www.realoem.com/bmw/enUS/showpar ... Id=17_0089
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
LMMarks
Joined: Fri 03 Jun, 2016 17:24
Posts: 12

  Z3 roadster 1.9i

Re: Coolant sensor location Z3 1.9i

Post by LMMarks »

Ah,

OK then well this may sound silly but I had assumed that was a second temperature sensor just for the auxiliary fan. So just to be clear, this provides the reading for both the dial on the dash and acts as the varistor switch for the auxillary fan and there isn't a second sensor on the cylinder head?

Thanks again for your help,

Laurence
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colb
Joined: Sat 05 May, 2012 22:46
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  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Coolant sensor location Z3 1.9i

Post by colb »

Description on diagram shows item10 as a double temp sensor it has two functions temp gauge and elec fan as far as I can see. To check the temp gauge ground the wire at the sensor end with ignition turned on, if gauge ok it should swing the needle across the full range. You could also use the dash self test function to verify the gauge works. If you don't know how to do this search forum for dash testfunction for full instructions
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: Coolant sensor location Z3 1.9i

Post by Del »

I believe on your car you may have two. The one mentioned above that controls the cutting in/out of the auxiliary cooling fan (if fitted) and part number 13621433076 screwed into the cylinder head (under the inlet manifold) that monitors coolant and oil temperature for feedback to the ECU for combustion mixture control (three way control with lambda & MAF sensors) . This latter sensor would act as a form of "choke" on a cold engine giving temperature feedback to ensure an enriched mixture during initial warm-up. :)
LMMarks
Joined: Fri 03 Jun, 2016 17:24
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  Z3 roadster 1.9i

Re: Coolant sensor location Z3 1.9i

Post by LMMarks »

I do believe I have two actually. My chassis number confirms on realoem.com that it is somewhere attached to the cylinder head and the radiator sensor is separate. I can't see where though. I had all the hoses, other sensors and covers out today, some of my car enthusiast friends at work were equally stumped. http://www.realoem.com/bmw/enUS/showpar ... Id=11_6190 . The replacement sensor I've bought is identical to the part you mention above. Has anyone changed one of these before?
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colb
Joined: Sat 05 May, 2012 22:46
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  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Coolant sensor location Z3 1.9i

Post by colb »

Sounds like Del identified where it should be under the inlet manifold as shown in the diagram if it's on your car it should be easy to spot under there as it will have the wiring attached to it, can you see or feel anything under the manifold?
Oem shows mine should have one but away from home at the moment so not able to have a look, will do when home again.
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
LMMarks
Joined: Fri 03 Jun, 2016 17:24
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  Z3 roadster 1.9i

Re: Coolant sensor location Z3 1.9i

Post by LMMarks »

We took the inlet manifold out to have a proper look and no sign of it. I appreciate it should be a pretty easy spot. Thinking about just taking it to the garage with my tail between my legs..
Del
Joined: Sat 19 Nov, 2011 18:35
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  Z3 roadster 1.9

Re: Coolant sensor location Z3 1.9i

Post by Del »

I've changed this sensor on my earlier 1.9 (M44 engine car) and it is under the inlet manifold. On many modern cars the coolant sensor is an integral part of the thermostat housing sometimes along with the auxiliary fan temperature switch - did BMW adopt this on some later cars?? Certainly on the new BMW minis, everything is wired to the thermostat housing.
LMMarks
Joined: Fri 03 Jun, 2016 17:24
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  Z3 roadster 1.9i

Re: Coolant sensor location Z3 1.9i

Post by LMMarks »

The diagram definitely seems to say its in the cylinder head, on the side. Perhaps it's further back than I've looked.
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colb
Joined: Sat 05 May, 2012 22:46
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  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Coolant sensor location Z3 1.9i

Post by colb »

I noticed the diagram also shows a plug and washer alongside the temp sensor could it be that some cars didn't have the sensor and the plug was used to blank the hole off? If this is the answer then it would only leave the one on the radiator which is a dual sensor
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
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Robert T
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Joined: Mon 12 Jun, 2006 10:35
Posts: 10170

  Z3 roadster 1.9
Location: Cheshire

Re: Coolant sensor location Z3 1.9i

Post by Robert T »

Looking at the diagrams, there appear to be three locations to check. There should be a double temperature switch in the side of the radiator, but there are two different radiators depending upon whether the car has aircon, and the location might not be the same between the two, however it should still go into the radiator. There is an electrical connection to the thermostat, which could contain a sensor. The one on the cylinder head can only be for either oil or coolant, not both, as it has a probe end that goes into the passing oil/coolant in the head. I can't see a second one under lubrication system (2.2i shows this as the same part number ), so my guess is that this oil temperature sensor.

Cheers R.

Sent from my SM-T810 using Tapatalk
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
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LMMarks
Joined: Fri 03 Jun, 2016 17:24
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  Z3 roadster 1.9i

Re: Coolant sensor location Z3 1.9i

Post by LMMarks »

An update: I've found the wretched thing at the back of the cylinder head. See my photos here https://www.dropbox.com/sh/o2x3lulooy8y ... x5H4a?dl=0. Access is very poor to the sensor so more likely than not more of the engine parts will need to come out. I intend to bleed the coolant first, to prevent the risk that it leaks over the engine, do you all feel this is necessary?
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colb
Joined: Sat 05 May, 2012 22:46
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  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Coolant sensor location Z3 1.9i

Post by colb »

Glad you finally found it, try a deep socket on it to remove it if you have room for an extension bar that will reach it.
I think you will be able to take it out and put the new one in without draining it as long as you do it when engine is cold and not under pressure, loss of coolant should be minimum if your quick but don't rush it and cross thread the new sensor screw it in to start it by fingers then finally tighten it with the socket.
Colb
1999 BMW 1.8 Z3
2003 BMW 2.5 Z4
1998 Honda Deauville NT650V
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Robert T
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Joined: Mon 12 Jun, 2006 10:35
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  Z3 roadster 1.9
Location: Cheshire

Re: Coolant sensor location Z3 1.9i

Post by Robert T »

From the diagrams, this looked more likely to be an oil temperature sensor - you will soon find out when you remove it!

If it is coolant, then you will need to drop the coolant below the level of the sensor, or it will go everywhere.

If it is oil, then the oil should be in the sump, so you shouldn't end up having to call Red Adair!

One thing you might try is disconnecting it and seeing if that has any effect on the temperature gauge. This would confirm that it is the right sensor.

Cheers R.

Edit: Having just read a thread on retrofitting ///M gauges to a non-M Z3, does the standard car even have a use for an oil temperature sensor?
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
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billysally208
Joined: Sat 11 Jul, 2015 12:53
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  Z3 roadster 1.9i

Re: Coolant sensor location Z3 1.9i

Post by billysally208 »

Are you sure that the sensor is faulty? I have had a problem over the last couple of days where on starting the engine of my 1.9 the temperature gauge was quickly going up to the maximum and the red warning light came on. The radiator fan was not coming on and like you I suspected the sensor or the fan - I then connected up to my Delphi code reader and tested the fan which was working ok - did a bit of internet research and read where one or two had similar problems and cured it by bleeding the system. I did this with only a small amount of air coming out and only adding half a litre of coolant and it did indeed cure it. I had it ticking over for over an hour with the gauge reading never more than halfway and the fan cutting in and outas it should do.
So obviously a small amount of air in the cooling system will make a big differene to the operation of the cooling system.
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