Engine Temperature and Sensors

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Jambers
Posts: 62
Joined: Mon Aug 28, 2017 9:41 pm
Location: East Midlands UK

Engine Temperature and Sensors

Post by Jambers »

Just for a laugh, I wonder if picture 1 causes picture 2, bearing in mind that the car had been sitting "cool" for at least 45 minutes?

The engine temp gauge has "hovered" and been a little erratic, and today I bled the coolant system at the Thermo housing bleed point, but there was absolutely no air in it at all and the expansion tank return pipe was sending water in with a nice stream. The gauge now shoots to the Red even with the just the IGN on (engine off).

Looking at REALOEM, I'm confused as to whether it is sensor 8 or 9. Looks like 9 - but 8 is the Gauge sender?
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Temp Guage.JPG
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Current cars:
1989 635CSi Manual
2007 Z4M Coupe
G31 530d M Sport
F21 118i M Sport
Based in the U.K. Leicestershire
Previously : F30, E60, E21, E30, E12, E28
brickwhite
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Joined: Wed Sep 01, 2010 3:29 pm
Location: Broomfield, CO

Re: Engine Temperature and Sensors

Post by brickwhite »

You can test the gauge by shorting the 2 leads with a piece of wire to see if the needle moves.

- Find the sensor by pulling the connector to see if the gauge goes to cold.
- If you short the connector and see the cluster at hot the gauge is working. Then check the ohms on the sensor...
- If you short the connector and nothing its the gauge or the wiring.... I'd look at that tape too.
- 12 535i
- 92 325ic
Jambers
Posts: 62
Joined: Mon Aug 28, 2017 9:41 pm
Location: East Midlands UK

Re: Engine Temperature and Sensors

Post by Jambers »

Thanks very much - will try this later this evening if I get 5 mins.


The connector is actually broken under the tape, and I fear that it is shorting. The car is in tomorrow for the statutory checks (MOT) and an oil service, so I'll get the garage to take a look at it. I don't know if a new connector plug is even available - if so with it being two wires I should be able to splice and shrink protect it back together if the garage can't fix it.

Hopefully the sender itself is fine under all that mess. I just wish that the previous owner hadn't bodged it! ](*,)
Current cars:
1989 635CSi Manual
2007 Z4M Coupe
G31 530d M Sport
F21 118i M Sport
Based in the U.K. Leicestershire
Previously : F30, E60, E21, E30, E12, E28
brickwhite
Posts: 797
Joined: Wed Sep 01, 2010 3:29 pm
Location: Broomfield, CO

Re: Engine Temperature and Sensors

Post by brickwhite »

The new connector can be purchased.
- 12 535i
- 92 325ic
ron
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Re: Engine Temperature and Sensors

Post by ron »

They are ALWAYS rustier than you thought!!!!!!
'85 M #228
'87 M #367
'88 High line.
'10 X5
‘84 Alfasud 1.5 ti
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Brucey
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Re: Engine Temperature and Sensors

Post by Brucey »

could be a short in the plug or something but could also be a fault in the cluster; the bulk of the restoring (leftwards) force in the gauge is electrical and can fail. This makes any temperature reading appear like the engine is really hot.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jambers
Posts: 62
Joined: Mon Aug 28, 2017 9:41 pm
Location: East Midlands UK

Re: Engine Temperature and Sensors

Post by Jambers »

Hi- so the plug, sensor and connector are actually OK. The metal retaining spring clip was missing and MSC have managed to find a spare one and fix it. The tape was merely holding the plug on.

MSC/Mike Smith Cars in Leicester (who are superb - they know these cars like the back of their hands and I can't recommend them enough) tested the engine temps and have confirmed that there is no over heating, and all systems (Thermostat, clutch on fan etc) are functioning as the boys back in Munich would have wanted.

The problem lies in the cluster - a sharp tap on the glass or the top of the dash makes it bounce around, so I suspect it's the lugs on the back of the gauge are either loose or need a bit of emery paper to clean them and make the earth solid.

A job for the summer!

Thanks everyone for your kind help. Thanks Ron - I suspected it would be plug 1 as it is a 2 wire jobby, but that is OK


...and the car passed it's MOT with no Advisories, so result!
Current cars:
1989 635CSi Manual
2007 Z4M Coupe
G31 530d M Sport
F21 118i M Sport
Based in the U.K. Leicestershire
Previously : F30, E60, E21, E30, E12, E28
Jambers
Posts: 62
Joined: Mon Aug 28, 2017 9:41 pm
Location: East Midlands UK

Re: Engine Temperature and Sensors

Post by Jambers »

Thanks all for the responses. I am going to attempt to fix the temp gauge soon, and I know that I need to:

1) Take the lower panel off (4 or so screws)
2) Remove the check control (pry screen away and remove 3 screws)
3) Take steering wheel off (22mm socket with Extension)
4) Undo 2 bolts and drop the steering column
5) Undo 2 screws/bolts under the cluster
6) Pull away the cluster and rest it on a towel or foam pad on column

But the question is that whilst on an e30 (according to the Youtube vid) there are exposed earthing bolts on the back of the Temp gauge (and fuel gauge) that could be tightened, photo's on the internet of the back of an e24 cluster do not clearly reveal the earth bolts in the centre top of the cluster backing cover.

Do I need to dis-assemble the cluster further first by removing the 8 screws on the back of rear surround?

Does the e24 gauge also have this earth issue, or am I looking in the wrong place or looking at the wrong type of fix?

Does anyone have a guide on what to do next? I also find that when I tap the glass on the cluster the speedo jumps a little (just a couple of MM and then pops back to where it should be). I think that I should fix that too but I don't know what needs to be done here, whether that too is a dodgy connection (looks like it)......

Also any other mods whilst I am at it? Light and bulbs a good clean?

Replace anything preventatively?

Thanks in advance.
Current cars:
1989 635CSi Manual
2007 Z4M Coupe
G31 530d M Sport
F21 118i M Sport
Based in the U.K. Leicestershire
Previously : F30, E60, E21, E30, E12, E28
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Brucey
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Location: Cambridge, UK

Re: Engine Temperature and Sensors

Post by Brucey »

if you don't want to remove the steering wheel you can just undo the two M8 bolts that hold the steering column to the dash underside and there should be (just) enough room with the column lowered to remove the cluster. It is a good idea to put a soft rag over the top of the steering column shroud to prevent scuffs on the cluster.

IIRC the temperature gauge, fuel gauge and SI indicator are all in one module and this plugs into the rest of the circuit board. There are many potential areas in which you could have a bad contact and therefore an erratic signal.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jambers
Posts: 62
Joined: Mon Aug 28, 2017 9:41 pm
Location: East Midlands UK

Re: Engine Temperature and Sensors

Post by Jambers »

Thanks mate - let the adventure begin [-o<
Current cars:
1989 635CSi Manual
2007 Z4M Coupe
G31 530d M Sport
F21 118i M Sport
Based in the U.K. Leicestershire
Previously : F30, E60, E21, E30, E12, E28
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