Temperature guage telling porkies???

Hi all, only owned the old girl for less than 2 weeks so i'm new to all this

She is a 1972 series 3 and the temperature guage is going into the red.
During the week i have thoroughly flushed the cooling system as it was rather brown, added new hoses, 82 degree stat and antifreeze of course.
There was no stat in it at all which started the old warning bells ringing.
The new stat is not opening with the engine running on my driveway so i've tested it and it's fine. I then put a thermocouple electrical thermometer probe down inside the top rad hose to the top of the stat and run the engine.
This shows a temperature of 79 degrees with her parked up with engine running and temp guage again in the red. Therefore the guage is misleading i suspect.
Is it possible i could have the wrong temperature sender in it seems likely or has anyone else had trouble with the guage itself??????
Any ideas are welcome.
Cheers

wot engine yu got, Matt as the series have a different engine sensor and gauge to, for example, the defenders. I had the same prob - changed the defender engine sensor for the series one

Funnily enough, was gonna ask this same question....

Put the 2.5 in, all sweet, new thermostat, temp in the red (Series gauge) Removes thermo, starts driving, climb a hill temp in the red, no boiling, bubbling etc.

So could be the temp sender being a 2.5, early defender sender then?

dats wot i reckon. unfortunately - i aint started the engine since to confirm it. But deffo different sender and interchangeable.

Sorry i forgot to say it's a 2 1/4 petrol, bog standard.
Done a 30 mile round trip today with no problems, just stayed near the top of the red.
Might see if i can pick up a sender tomorrow just to make sure i have the correct one.
Will let you all know how i get on.

Cheers.

I fitted on of theses
TIM Gauges Water Temp Gauge Capillary Black Face (TIM005)

POTN - Gauges - TIM - TIM Gauges Water Temp Gauge Capillary Black Face (TIM005)
and it confirmed that she was runing just right.
Ps
Ignore the pic on this site it's the wrong pic.

Ere' Clive, ow' do you fit one of them then? Is it easy? I quite like having guages to look at, tho' not sure if it gives peace of mind or increases paranoia!

I'm moving all my dash about soon so I might put a couple of extra guages in just for the feck of it really.

Put the series sender in.............. Still the same.

Codbasher said:

Put the series sender in.............. Still the same.

Click to expand...

That's odd then.
I'm hoping to get an old guage off my mate to compare with mine.
I wonder if it could be a wiring fault in the loom.
Could try running a temporary wire from the sender direct to the guage to see.

I have a little inkling that it could be electrical.....



But, do need a piccy of the heater/cooling system first to see where the feed and return to the heater are in relation to the head on a 2.5 NA, as my sender is located near the rear of the head, and I have a feeling it should be by the thermostat, yet this is where the heater return goes....

Bloody lucas electrics, its no surprise that he's called the prince of darkness in biker circles

Ive had a gauge reading just over cold for years, and another reading red for weeks, both on a series 3 diesel, this was the gauges fault.

Get a mate with a series landy, and a length of wire, park close to each other and connect his gauge to your sender unit and / or your gauge to his sender unit. as long as at least 1 of the landys has a relatively good gauge this will show you if its the gauge or sender thats out. (oh you'll need to complete the earth side of the circuit too, i used a jumper cable across the 2 front bumpers)

alternatively just swap the gauges/sender units when your mates not looking . . . . )

REMEMBER. never trust advice from unqualified sources

Codbasher said:

I have a little inkling that it could be electrical.....
But, do need a piccy of the heater/cooling system first to see where the feed and return to the heater are in relation to the head on a 2.5 NA, as my sender is located near the rear of the head, and I have a feeling it should be by the thermostat, yet this is where the heater return goes....

Click to expand...

Hi Coddy, soz to hear new sender didnt work - bugger - coz i fitted one as well. sender is deffo just under the thermostat on offside off engine. If yu need a pic - i will post one.
it can only be one of three things -
sender
gauge (note spelling)
voltage regulator.

all instruments use a regulated 12v supply that then goes through a gauge and then the sender to earth. It is inherently a ridiculously simply system.

Get the capillary gauge no electrics to go wrong and it works all the time
Not sure where they go in the S3 but in my s2 it went in just below the thermostat housing on the off side where the standard water senor is.

The way I tested mine was with a cup of hot water and you can have a nice cup of tea as well.

My sender is at the rear of the head, between 3 & 4 cylinder, me thinks that is where the heater hose should be....

this is mine - on a 2.5litre

The Mad Hat Man said:

this is mine - on a 2.5litre

Click to expand...

Yep thats where it goes on a 3 bearing 2.25 petrol as well.

Yeah that's it. Picked up a new one today for the hell of it as it's only a couple of quid. Gonna carefully check the wiring behind the instrument panel before fitting it. It's like a birds nest behind there.

Can anyone explain what the cold start light thingy is all about, the one with the other sensor on the head and the odd looking thing on the choke cable??

careful when removing wire as they like to snap off in yer hand and I had to strip the harness back to repair, not difficult but still another annoying little job to do

Sidz said:

careful when removing wire as they like to snap off in yer hand and I had to strip the harness back to repair, not difficult but still another annoying little job to do

Click to expand...

Will give you a shout if that happens then, I'm only in south devon myself
I'm quickly finding out that 35 year old wiring looms are delicate.

My cold light comes on when the engine is up to temperature and the choke is still on.
I have not been able to find any thing in the manuals that confirms that but it seems logical.