Radiator Blind

[ALISCAR]

From the start of the cooler weather last autumn, our Traveller engine has apparently been running cold. Putting in a new 88deg thermostat has not improved matters. Could be a faulty temp gauge but heater output and tickover suggest actual cold running. Neither ESM nor Charles Ware list a rad blind. Anyone got a good solution for partially blanking the radiator, preferably with variable blind. This car is in daily use. Nigel Orchard (family member but chief mechanic)

[ianmack]

People used to experiment blanking the grille with cardboard, wood, plastic, anything handy really. Don’t cover it entirely and keep a close watch on the temperature gauge. The most professional looking covers were sheet aluminium although it is harder to make these adjustable.

[alanworland]

I used to use what was essentially a roller blind in front of the rad behind the grill, it was a proper motoring accessory sold by 'Gamages' operated by a chain within the car.
Worked fine and you could go quite a few miles with it fully closed - but you had to keep and eye on temp gauge!
Downside was when maintaining any reasonable speed the air pressure in front would prevent it opening until you slowed right down - which is not always convenient!
Electric fan now installed.

Alan

[geoberni]

Dare I suggest taking a step back and looking at this problem with a different approach.

You say

From the start of the cooler weather last autumn,

but 2 things, firstly, by that do you mean 3-4 months ago, or 14-15 months ago? Secondly, what's it like in the Summer?

The basic system as designed is sound, after all, they never changed it in some 30 years of operation.

So it begs the question as to what is really going on?

If you truly haver an engine that is running a little cooler than most of it's compatriots, then rather than a variable device, why not simply fit a cover to a portion of the radiator during the winter months?
Perhaps no more than a 1/4 of the overall matrix area and see how that goes? A section of cereal box would suffice to experiment with.

[Myrtles Man]

Many years ago I too had concerns about the cool running of the cars I had at the time. After experimenting with various sizes of pieces of blanking (hardboard, cardboard, whatever) I eventually got tired of having to quickly release the bonnet latch, bail out of the car, nip round to the front and remove (as best I could without burning my hand or making my clothes filthy) the blanking sheet when, caught in a traffic holdup, the temperature needle started to head for the danger zone. I therefore came up with the simple wheeze of acquiring, cutting to size and fitting (upside down of course) a small domestic roller blind (plastic sheet rather than fabric) with a long piece of nylon cord (instead of the supplied pull-cord) routed over the top of the rad and the engine and through a hole in the bulkhead to the parcel shelf area in front of the driver. It worked fine; I still had to keep a close eye on the temp gauge but it was easy enough to release the blind and let the spring lower it, leaving the full radiator surface free to do what it does best. It worked for me.

[RobThomas]

I bought and fitted a Factory Option roller blind for the rad. Ideal on a sidevalve with that massive header tank. Obviously, the numberplate didn't stay there!

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[oliver90owner]

As I see it, either you have no problem (measuring the coolant temperature properly, would be my first check for that) or coolant is passing the thermostat at a too low temperature - maybe checking the radiator to see if it is warm before the engine is up to temperature would be a check for that. Maybe you have an air-lock or constriction in the heater?

Blinds only really help if the weather is bitterly cold, when the cold air cools the engine without needing coolant flow through the radiator, usually just retarding the warm-up process.

I used to run my cars (back in the 60/70s) with a slowed water pump (and no fan for long periods) without too much trouble. The ignition key is always a means of preventing overheating in traffic jams - but much fewer hold-ups back then, of course.

[ALISCAR]

Dare I suggest taking a step back and looking at this problem with a different approach.

You say

From the start of the cooler weather last autumn,

but 2 things, firstly, by that do you mean 3-4 months ago, or 14-15 months ago? Secondly, what's it like in the Summer?

The basic system as designed is sound, after all, they never changed it in some 30 years of operation.

So it begs the question as to what is really going on?

If you truly haver an engine that is running a little cooler than most of it's compatriots, then rather than a variable device, why not simply fit a cover to a portion of the radiator during the winter months?
Perhaps no more than a 1/4 of the overall matrix area and see how that goes? A section of cereal box would suffice to experiment with.

It ran just below centre position of temp g/g until about Autumn 2019 when weather got colder but not very cold. Fitted 88deg thermostat but temp continued to show down at cold end of g/g even after good run. Anyone had a duff new thermostat? I'll follow another suggestion on this list and check manually on the rad if it does get warm water before it should. It now needs to have small amount of choke (at the tickover increase end) or it stalls when "hot". It used to be the case that you could only put the choke fully in when the temp g/g showed nearly working temp which suggests to me that ti is actually not warming up rather than a faulty temp g/g. My thanks for all suggestions so far. Delay in replying due to password problems. Nigel

[liammonty]

Assuming your gauge is working correctly, I’d imagine it is a dud thermostat. All the Minors I’ve owned have managed to warm up fine - my current car (which has a gauge that I’ve fitted) has an 88 degree thermostat in it and runs at the same temperature all year round. I’ve never needed a radiator blind even in the coldest of weather (i.e. sub zero) so I suspect if you get yours working as it should, you’ll be fine

[geoberni]

It ran just below centre position of temp g/g until about Autumn 2019 when weather got colder but not very cold. Fitted 88deg thermostat but temp continued to show down at cold end of g/g even after good run. Anyone had a duff new thermostat?

I think you've said it, it was fine until you fitted the thermostat. Was the old one duff then , your tale just make it sound as though you randomly fitted it without reason...

I brought a Laser Digital Thermometer 'gun' from ebay about a year ago (about £8.50) and it's been a great investment for checking temps.
I was even able to calibrate my adjustable Smiths Gauge to be mid range when the thermostat housing area was showing approx 88/90 deg.

[Edward1949]

Assuming your gauge is working correctly, I’d imagine it is a dud thermostat. All the Minors I’ve owned have managed to warm up fine - my current car (which has a gauge that I’ve fitted) has an 88 degree thermostat in it and runs at the same temperature all year round. I’ve never needed a radiator blind even in the coldest of weather (i.e. sub zero) so I suspect if you get yours working as it should, you’ll be fine

Agreed. In fact after a stone-cold winter start my Minor heater blows heat quicker than my modern car. The temperature should "sit" at the figure set by the thermostat. Trying to cure it by fitting a blind is not getting to the root of the problem. The best use of a blind is for heat retention in the engine bay of a vehicle used intermittently throughout the day.
Ref ALISCAR's problem: once well-warmed up, do the heater hoses feel just moderately warm, about the same as the top of the radiator? If so you've probably got : a dud thermostat, or blocked/airlocked heater pipes/matrix, or heater tap not fully on. After a reasonable run the metal piping section of the heater hose which runs along the cylinder head should be uncomfortably hot to the touch, whereas the radiator can often be just lukewarm.