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SimonMB

Member Since: 12 May 2023
Location: Palma
Posts: 2

Erratic Temp Guage

Hi
A few months back I bought my first Defender TD5 110 2004. I'm slowly sorting out all the niggles but am struggling with erratic temp Gauge and no cabin heat.

It seems like as the thermostat opens the needle flicks into the red and truck goes into limp mode for a second or so. Needle then backs off but still reads high temp. After some time driving / idling the needle will settle back down to just left of centre. Sometime the needle just backs to the 'off' position

When I turn the truck off I can hear what sound like big air bubbles in the cooling system running down from the heater box.

Both lines to the heater box are warm and the flap seems to be working fine

Do you think that bubbles in the cooling system could be causing some of issue? I presume the issue is also electrical.

I have looked a the temps sensors and the wiring seems okay and not chaffed around the front of the motor

Looking from some guidance on what to check

Thanks

12th Jan 2024 1:39pm

landy andy

Member Since: 15 Feb 2009
Location: Ware, Herts
Posts: 5731

2006 Defender 110 Td5 USW Zermatt Silver

You have a coolant issue if you have air in it.

The temp gauge isn’t a real reflection of temp, like most these days it’s controlled by the ecu. So works like a “proper” temp gauge up to about half way, then if the ecu detects an over heat, will immediately go straight to the RED.

Possible you just have air in system such as heater matrix, but could be another issue such as failed head gasket. Are you loosing coolant at all?

12th Jan 2024 3:08pm

SimonMB

Member Since: 12 May 2023
Location: Palma
Posts: 2

Thanks,

Yes I noticed some coolant loss today. It seems like it came from the top of the bottle. Cap was tight but maybe not sealing correctly.
I suppose no heating in the cabin also points to something coolant related.

But also odd the gauge goes completely dead sometimes

I’ll keep investigating…

12th Jan 2024 7:14pm

jimbo55

Member Since: 15 Jul 2020
Location: Midlands
Posts: 399

The heater matrix can be a pain to bleed, I ended up loosening the clamp on the return to try to make sure the matrix was full of coolant and not air

May be also worth checking the connections in the dash to your speedo and temp gauge, the speedo damps the temp gauge in a td5

13th Jan 2024 11:49am

Martin
Site Admin

Member Since: 02 Apr 2007
Location: Hook Norton
Posts: 6611

2015 Defender 90 Puma 2.2 XS CSW Montalcino Red

Speedo doesn’t get involved with temperature gauge. Fuel gauge yes, not coolant.

The sudden jumps could be a loose connection, either at ECU or cluster pack end.

1988 90 Td5 NAS soft top

2015 D90 XS SW

13th Jan 2024 1:08pm

Mo Murphy

Member Since: 01 Jun 2008
Location: Letchworth Garden City, Herts
Posts: 2247

1984 Defender 90 BMW M57 3.0 Diesel HT Auto Pennine Grey

The speedo only modifys the temp gauge reading in ROW vehicles that were 300tdi vehicles built in the time of the TD5 with TD5 dashes.
Mo The Land Rover 90 - Many are called, few are chosen.

50 Shades of Pennine Grey

13th Jan 2024 4:23pm

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