What's wrong with my temp gauge?

[wally]

The standard temp guage on my 300Tdi has started showing high temps. The engine doesn't appear to be running that hot though, and my TM2 engine watchdog is still showing normal temps. Also, if I switch off the engine while the guage is showing hot, and then start up again, the guage is back to normal again. I just replaced the temp sender and it has made no difference, much to my disappointment. Could I have a dicky guage? Any ideas? Any suggestions?

[rick130]

These things are notorious for playing up and it usually relates back to a bad earth for the instruments.

Can't recall where the instrument earth is, it's in behind the dash there somewhere, but that's where i'd start.

Mine started to climb one rainy day crossing the range here and I near pooped myself as I thought I'd cooked the engine.
Turned the wipers off and the temp dropped :rolleyes:

I just couldn't be bothered chasing it so installed a VDO mechanical gauge years ago, it eliminates the problem.
The VDO thermowell screws straight into the OE spot, then the feeler bulb screws into that.

[wally]

These things are notorious for playing up and it usually relates back to a bad earth for the instruments.

Can't recall where the instrument earth is, it's in behind the dash there somewhere, but that's where i'd start.

Mine started to climb one rainy day crossing the range here and I near pooped myself as I thought I'd cooked the engine.
Turned the wipers off and the temp dropped :rolleyes:

I just couldn't be bothered chasing it so installed a VDO mechanical gauge years ago, it eliminates the problem.
The VDO thermowell screws straight into the OE spot, then the feeler bulb screws into that.

Rick, I like the idea of that. Where do I get such a thing? Any chance of some part numbers?

[rick130]

VDO part # 180 077 022

52mm OD, 1600mm capillary.
The correct thermowell comes with it from memory and the gauge just slots into the dash, replacing the existing one.
I killed one by having the capillary rub through on an injection line it was cable tied to and it wasn't cost effective to get it repaired so ran the capillary through some corrugated tubing next time.

I also smeared some thermo paste/heat transfer paste all over the feeler bulb before inserting it in the thermowell. Probably just being a pedant, but I felt better doing it :D

You might have to hunt around for a VDO stockist but most spare parts stores should be able to get them in, might even be a list on the Siemens/VDO Australia website.
I bought mine through an instrument repairer in the nearest large town.


http://www.aulro.com/afvb/attachment.php?attachmentid=28156&stc=1&d=1282723197

[wally]

Excellent. Much appreciated Rick.

[lokka]

Rick you are a champ i will be doing the same to the county now :cool:

[MinniTheMoocha]

I recently fitted a VDO temp sender and gauge to my Defender. It is much more accurate and was partly prompted by the OEM gauge showing normal until it finally gets to the upper limits. The cause was mud that filled in between the radiator fins and dried.

For those interested I have listed the part numbers below. I purchased mine from Ringwood Speedo's Maroondah Hwy Ringwood Victoria.

Now for the interesting part. The gauge shows 90°C In the morning on the way to work but 95°C on the way home. I've yet to work out why. Any ideas? Its a new thermostat too!

VDO cockpit vision Temperature Guage

https://www.aulro.com/afvb/images/imported/2010/08/297.jpg (http://www.aulro.com/app/showphoto.php/photo/18466/title/vdo-temperature-gauge/cat/1059)

Part No. Range
310 010 014 K 40-120°C


VDO Water Temp Sender

https://www.aulro.com/afvb/images/imported/2010/08/298.jpg (http://www.aulro.com/app/showphoto.php/photo/18469/title/vdo-temperature-sender/cat/1059)

Part No. Range Thread
320.002 40-120°C 1/8”-27 NPTF

You will notice that you have to change the connector on the sender wire to a female spade electrical connector instead of the bullet type.

[josh aka sean]

I am pretty sure i have the same gauge in mine. Are you running lights when you drive home?? I find that it shows around 90 (just under normally) until i turn the lights on then it instantly jumps to 95ish then if i turn more things on (ie indicators or windscreen wipers) it goes up a bit more. I'm thinking I have a dodgy earth on the gauge. Yet to investigate however.




Now for the interesting part. The gauge shows 90°C In the morning on the way to work but 95°C on the way home. I've yet to work out why. Any ideas? Its a new thermostat too!

VDO cockpit vision Temperature Guage

https://www.aulro.com/afvb/images/imported/2010/08/297.jpg (http://www.aulro.com/app/showphoto.php/photo/18466/title/vdo-temperature-gauge/cat/1059)

Part No. Range
310 010 014 K 40-120°C


VDO Water Temp Sender

https://www.aulro.com/afvb/images/imported/2010/08/298.jpg (http://www.aulro.com/app/showphoto.php/photo/18469/title/vdo-temperature-sender/cat/1059)

Part No. Range Thread
320.002 40-120°C 1/8”-27 NPTF

[MinniTheMoocha]

It just might be. I will have to check the earthing on the weekend.

[bee utey]

For random earthing fix: Isolate the gauge earth from the loom, run a totally separate earth wire from the gauge to a bolt somewhere near the temp sender. That takes out ALL random current paths. Remember to leave the illumination globe earth wired to the body earth as bulb current can upset a gauge too.

[wally]

I've just ordered a VDO mechanical guage from Autobarn but in the meantime I borrowed an infrared thermometer from a mate. What a bloody marvellous thing that is. I was able to confirm very quickly that while the standard guage was reading almost in the red, both the infrared thermometer and the TM2 engine watchdog indicated that at the bottom thermostat bolt the temperature was 77C. At the back of the block the temp was 86C.
So I know at least I can keep driving it now and just ignore the standard guage. It makes me pleased that I have the TM2 as a reliable backup.

[wally]

To round out this thread: I fitted the VDO mechanical guage (thanks again to Rick for the part number). On a half hour run up the highway it never went above about 82C :D. So I have peace of mind again. And I would recommend to anyone to replace their standard guage with one of these.

[Johnno1969]

It also helps to have a really clever mate around on these jobs, in case anything goes wrong.

[wally]

It also helps to have a really clever mate around on these jobs, in case anything goes wrong.

And some patience.

[scoota]

had similar problem with my defender - it ended up being the headlights. Don't exactly know how but when i replaced the loom and lamps the problem disappeared.
Scoota