Does the instrument voltage regulator need to be metal to metal at the instrument cluster or can it attached with double side tape or an adhesive glue? I am getting a high temp reading.
I have had the radiator core cleaned out and made sure water pump impeller clearance is to specs.
Currently running a 160 deg thermostat with the original type Cooper S cast iron pump with bypass.
Will be taking the car over to the radiator people to do a reading with a thermal temp guage and check for combustion leaks.
Any thoughts from the experts?

The voltage stabiliser needs to be earthed



Things to look at

The gauge may need adjusting.
Incorrect sender.
Voltage stabilizer stuffed.
Low coolant flow from blockages, water pump wear or speed, thermostat not opening.
Low system pressure from leaks (external or internal) or low cap pressure.
High engine cylinder temp (Timing or running lean).
Airflow through radiator, fan on the correct way, loose fan belt, blocked or bent fins.

It needs to be earthed somehow - I had the same issue with the temp gauge reading way too hot. Changed gauges, temp senders, etc but made no difference.

Once I earthed the regulator it actually reads correctly. I made a short earth strap that goes from the retaining screw into the firewall just to be safe.

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67 Van, 1275cc

It is fundamental that the regulator is earthed. Otherwise it does not have a reference

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1960 Morris Mini Minor

I would unscrew the sender from the block, earth it with a alligator clip and suspend it in a kettle and boil the kettle to test the gauge. Use a thermometer if u want to know what normal and hot represents. You need the ign on so unplug the coil so u don’t damage it.

If an old style volt stabilizer is dodgy the reading may vary while driving. The electronic replacements are much better.

You can buy cheap laser temp readers from eBay. Worth having.

Bear in mind minis were never great at staying cool esp 1275. With a 82c thermostat if stuck in traffic mine gets quite hot. Prob over 100c but has never boiled (and shouldn’t if system is holding pressure). I sometimes swap to a 74deg thermostat in summer.

Double check your thermostat opens properly at correct temp in a pot of water on stove.


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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

Just an update. Once I earthed the IVR correctly, the temp guage is working correctly. Mind you I overthought things, thinking it was a cooling system circulation problem, so I removed the water pump and corrected the impeller clearance. While the radiator only had 2 more bolts to remove, I sent it over to my radiator repairer to check it out. It had 3 cores blocked.
Another thing they said was don't use Nulon Coolant, especially with alloy heads.

Thanks for the update.

Did they say why they said that about (not) using Nulon?

Yes also wondering why not nulon. Our club visited Nulon factory and they really sounded like they knew their stuff.


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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

This radiator has been in business for many years and are a trusted company in this town. They, over the years when they see a problem, especially with alloy heads, they ask what coolant have they been using and the answer is usually Nulon.


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Is the right formulation of product being used by the operator? What sort of "problem" are they referring to?

In any case though the heads on my Minis are not alloy.

Providing the water pump isn't alloy.

Hi Dave, but you do have alloy components in the cooling system....

The guys at Phillip reckon you don’t need (and shouldn’t use) antifreeze in Canberra (unless you plan on leaving the car in the Perisher car park for a week:).

When they did my rad a year ago they recommended some lubricant/corrosion inhibitor instead. It contains something called triethanolamine... which sounds pretty nasty going by the warning labels on the bottle..... but it seems to work.

Interestingly they also recommended against an alloy radiator ... although they do like them because they bring in lots of repeat business.

Cheers, Ian

I would be running anti-freeze in Canberra. I'm damaging too many things in Goulburn from water freezing, to risk a car without anti-freeze is insanity.

Did they say why they don’t recommend them? I was planning on grabbing one for the 1275.