Temperature Gauge Calibration

[Westfaling]

Guys
Can the temperature gauge be adjusted? My gauge looks like this when running normally (idling or mobile).
Temp.jpg
It was worrying me as the gauge climbed to 3/4 on a recent -very slow hill assent. (Bloody slow tourists!!)
Oct Run 4.jpg
However I just checked the under bonnet temps with the gauge in the position shown (with two different infra red thermometers)
The casting at the rear of the LH head was at 74 C. (Where the temperature sensor is)
The temp at the top of the radiator (at the filler) was 83 C
These temps don't concern me but will probably be a bit higher with the bonnet closed.

My concern is that there's not much gauge travel left before it hits the red so I'd like the gauge to read lower.
Any thoughts.
Nick

[stag8manod]

Nick, My suggestion would be to replace the factory electrical guage with a full scale mechanical guage. My temperature bulb is fitted just to the rear of the thermostat. Cheers Ian A

[V Mad]

Hi Nick. The gauges can be recalibrated but they are delicate and require a light touch. I did all mine before I fitted the dashboard.

But also, if you havent alreay got one try the LD Part temp sender; that reads lower than most of the others available, which apparently read higher than they should.

[wilf]

Have a think about this.

It really doesn't matter where the needle sits when things are "normal". The gauges are not accurate enough to worry about that.

All you are looking to spot is needle movement away from the "norm".

So get used to what your gauge does, accept that it is what it is, and only worry if it moves significantly higher than that.

[Westfaling]

Wilf
I take your point but I'll likely be in the red and pulled over at the side of the road when the actual temps are still okay. By the time the coolant reached 100 C I'll likely be off the scale on the gauge.
I just ordered a sender unit from LD - seems the simplest solution.
Thanks guys.
Nick

[wilf]

Nick - it may be worth trying this - wire the sensor up so it will work (will need an earth connection to the body) without being actually fitted. Then drop it into a travel kettle or similar of boiling water, and observe where the gauge settles. Voila! Simple calibration for 100C.

[Westfaling]

Wilf
Thanks I think I'll give that a try when I get the new sensor. I only want to drain the system once.
I'm thinking of using a spare fuel pump to suck out the rad through the filler plug down low enough to empty the heads of coolant. (As I've no rad drain cock) and it always seems such a messy business.
Nick

[wilf]

That should work, I drained my own via the radiator neck (and a syphon tube, but be careful not to swallow any antifreeze!) when I swapped my own sender over for the mechanical gauge I fitted.

[Marco Polo]

Wilf
Thanks I think I'll give that a try when I get the new sensor. I only want to drain the system once.
I'm thinking of using a spare fuel pump to suck out the rad through the filler plug down low enough to empty the heads of coolant. (As I've no rad drain cock) and it always seems such a messy business.
Nick

Nick,
If you use about 800mm of copper plumbing pipe and attach it to a length of clear hose you can place the copper pipe into the radiator filler neck and the suck on the clear pipe
and then siphon the fluid out of the rad into a bucket. The copper pipe reaches the bottom of the rad and the clear pipe gives you ample warning so you don't get a mouthful of antifreeze/coolant.
regards,
Raoul

[Mike Stevens]

Nick,
If you use about 800mm of copper plumbing pipe and attach it to a length of clear hose you can place the copper pipe into the radiator filler neck and the suck on the clear pipe
and then siphon the fluid out of the rad into a bucket. The copper pipe reaches the bottom of the rad and the clear pipe gives you ample warning so you don't get a mouthful of antifreeze/coolant.
regards,
Raoul

Neat. I shall try that next time I need to drain down!

Cheers,
Mike.

[chopperman]

Halfords sell a very cheap plastic hand operated siphon. Saves getting a mothfull of antifreeze

[Westfaling]

I fitted the LD temp sensor and took the car for a good run. Not a hot day 15C but running or idling the the gauge now reads like this.
Gauge2.jpg

The temp at the rear of the head was 77C immediately on opening the bonnet and top of the rad was 82C. I took a reading off he core just after I stopped the car and there was a good 13C difference top to bottom. I'm happy with that and am declaring my cooling system okay...
I may still fit a back-up Kenlowe in front of the rad as Stag Paranoia knows no bounds


FYI sucking out the rad doesn't do much to drain the head. Did that but coolant still gushed out when I removed the temp sensor! I think the water pump acts like a trap limiting the gravity drainage from the head(s).

Nick

[Westfaling]

Anyone think there's any advantage in now closing this thread??

[DJT]

FYI sucking out the rad doesn't do much to drain the head. Did that but coolant still gushed out when I removed the temp sensor! I think the water pump acts like a trap limiting the gravity drainage from the head(s).

Nick

No, but it does mean that a radiator full of coolant doesn't gush all over you as you remove the bottom hose. It also means that this coolant can be collected in a controlled fashion for either re-use or proper disposal. It shouldn't be allowed to disperse into the drains or watercourse, or be left on the road/driveway where animals can lick it.

Have you tried disconnecting the top heater hose whilst siphoning the radiator? This can allow air in at the top of the engine, thus coolant can drain down easier.

[Westfaling]

Dave
Good point antifreeze ain't cheap either. Took the car for another run this morning a much more clement day 27C. Temp gauge didn't budge. Very happy camper now.
From this I conclude that the thermostat must be doing most of the temp control under normal operating conditions as the temp doesn't change when idling in the garage or at 70mph. Long slow hill assents seem to be the only thing the thermostat can't cope with so the back-up Kenlowe will still be fitted before my outing to Taupo in Feb.
Nick