strange temp gauge?

[robertjones]

Noticed on my z, the temp gauge moves up to the halfway mark after maybe, half a mile of setting off from home , even though the engine hasnt warmed up, it then stays there however fari travel, uses no water and fan kicks in o.k. , doesnt seem to overheat Is this normal ? As my last z would run for quite a while until the engine warmed up before moving to normal, engine is 1.9i

 

[Brian H]

Robert,

If it aint broke don't fix it , the temp gauge is a buffered gauge so when the needle sits in the middle it will cover a range of 20 or so degrees.

Brian

 

[robertjones]

Agree with u but just think its unusual and wondered if anyone elses z was the same , as I have never had a gauge that worked llke that before as soon as I leave the house the temp starts showing a reading

 

[GazHyde]

Doesn't take very long to get to the middle on my 2.2.

 

[Brian4]

Same in ours gauge quickly to mid point and heater blows warm air about 5 mins later.

 

[robertjones]

Same in ours gauge quickly to mid point and heater blows warm air about 5 mins later.

Sounds as if its the norm. For some of these cars then, unless yours is unusual as well!

 

[oldcarman]

Anyone had intermittent temp gauge problem? Works normally or not at all? JIM

 

[hard top]

Problems in the bedroom department Jim?.......

 

[t-tony]

Mine does the same as Gaz and Brian's cars. I've had it over 4years now and it's never been any different.
As Brian H said and I agree.

Tony.

 

[Brian4]

Just looking on the wiring diagram for the Z3 and the coolant temp sensor for the gauge is at the rear of the cylinder head under the inlet manifold so it will get to see any heat pretty quickly perhaps that is why is rises fast initially. It also feeds through the DME control unit and this gives the analogue output to the temp gauge. Electronic wizardry so the likes of most of us cannot understand.
Gone are the days when one sensor is connected directly to the display for that item.

The speedo isn't driven by the gearbox but by the wheel speed sensors used by the ABS and AST or DSC and a sensor in the rear axle.

 

[zedonist]

Anyone had intermittent temp gauge problem? Works normally or not at all? JIM

I've found mine does not work when i switch the engine off, it works again when i switch it on, must be an intermittent design fault.

 

[t-tony]

Speedo cables are long gone Brian, except if the elastic has gone in them.

 

[robertjones]

Just looking on the wiring diagram for the Z3 and the coolant temp sensor for the gauge is at the rear of the cylinder head under the inlet manifold so it will get to see any heat pretty quickly perhaps that is why is rises fast initially. It also feeds through the DME control unit and this gives the analogue output to the temp gauge. Electronic wizardry so the likes of most of us cannot understand.
Gone are the days when one sensor is connected directly to the display for that item.

The speedo isn't driven by the gearbox but by the wheel speed sensors used by the ABS and AST or DSC and a sensor in the rear axle.

Blimey, no wonder it goes up so quickly!

 

[Brian4]

Speedo cables are long gone Brian, except if the elastic has gone in them.

Point I was trying to make Tony.

 

[zedonist]

Just a clarification the speedo is controlled by a fan disc and sensor in the differential only, the wheels spin at different speeds at different times during driving so would not be much use to the speedo.

 

[jonco]

Robert,

If it aint broke don't fix it , the temp gauge is a buffered gauge so when the needle sits in the middle it will cover a range of 20 or so degrees.

Brian

Agreed - if you have access to INPA - engine module you can see the temp readout varying by ~10 degrees as stat controls even though instrument cluster temp guage remains steady. Maybe stat was faulty on previous Zed hence slow warm-up.

 

[oldcarman]

Problems in the bedroom department Jim?.......

Nothing a couple of tongue depressors and elastic bands can't overcome. It's the slivers that are the problem but I think if I use sandwich wrap first should be a go!! What are you using?

 

[oldcarman]

I've found mine does not work when i switch the engine off, it works again when i switch it on, must be an intermittent design fault.

Thanks, I didn't get any owner manuals with the car. I'll see if that works now that you've cleared that up. JIM

 

[zedonist]

Thanks, I didn't get any owner manuals with the car. I'll see if that works now that you've cleared that up. JIM

It's still intermittent Jim, as I say, but I will sort it out soon.......let you know the solution in another three years......

 

[vintage42]

... the temp gauge is a buffered gauge so when the needle sits in the middle it will cover a range of 20 or so degrees...

More than that. The needle reaches vertical resting point at 155F and stays there until 205F, the highest I have seen my 1.9's temperature go on the ScanGauge sitting in traffic on a hot day.
http://i49.photobucket.com/albums/f280/vintagefortytwo/BMW Z3 Related/ScanGauge/ScanGaugeOn_zps0ee4d6bf.jpg
My (one electric) fan turns on shortly after 200F, so I have never seen at what temperature the needle might go past the vertical toward the red.
The needle stays vertical throughout a wide operating temperature range, even as the ScanGauge shows the actual temperature varying constantly with driving conditions.