To blank grill in winter - or not ?

[paulhumphries]

My car had a new radiator just before I bought it and even during this current cold spell the heater is getting warm within 1/2 mile.
Today I did a little experiment.
I completley blanked off the grill and took the car for a run.
When warm I then did around 5 miles at 50-60 mph on a dual carriageway.
I don't have a temperature gauge in the car but checked the rad temp with a laser thermometer - approx 80 degrees.
No increase even allowing the engine to tick over.
The grill was then uncovered and the same dual carriageway journey done the other way at same speed.
On checking the rad temp was now only, approx, 65 degrees.
There didn't seem to be any noticable difference in the heater output (measured on the back of my hand as the laser thermometer isn't suitable for airflow - just objects) either blanked or open.
My opinion is to blank as the car will be more efficent.

Question therefore is what do other people do in winter - blank or leave open ?

Paul Humphries.

[bmcecosse]

First step for a good heater is to fit an 88 degree thermostat for winter running. This helps quite a bit. You can also remove the fan in winter - provided you don't do much town work - and you really need a temp gauge to make sure you don't boil it. Blanking the grille will help to keep salt and filth off the rad - so provided it's just for normal motoring - do it! Be aware that a good deal of the air goes in through the slots below the bumper - and not just through the grille bars.

[8009STEVE]

If you want a cheap grill cover, I use tin foil. Just blank the whole lot off. if you start to overheat, then put a few finger holes in the foil until you get it right.

[bmcecosse]

Or thickish plastic sheeting is a little less 'obvious'.

[eastona]

I bought a pukka radiator muff for mine at the start of the winter, I'd post a picture, but I've failed to work out how to do it....how do you do it???

It's got little flaps and a cut out for the heater. It's great, with hot heater 1-2 miles into a journey even down to -2. Having water in the radiator helps, as I found out last week what a plonker.

BMC's right, an 88 degree helps, I fitted one too.

Andrew

[rayofleamington]

The thermostat will regulate the engines temperature as much as possible. Blanking the radiator just makes the radiator less efficient - therefore the thermostat will open more (until it is fully open all the time).
When the thermostat is more open, you should get LESS flow through the heater (it gets worse). In practice, it is very hard to tell any difference. If you get the water hotter than normal, then you are overheating.

The downside of a blanked off radiator is that if/when the thermostat is fully open all the time, there is no contingency left in the cooling system and if the temperature starts to rise, you will cook the engine. Overheating the engine isn't a risk I'd take for making the heater warmer.

A higher rated thermostat will be more closed (at a given temperature) - creating slightly better flow through the heater, and the water should be a little warmer too.

As for the time talken for the heater to get hot - if your thermostat is working correctly, the radiator (blanked or unblanked) has no effect. The heater should be heat up before the thermostat allows water flow the radiator.
If your heater takes ages to get hot, then either
1) you have poor water flow to the heater matrix (blocked matrix or pipes, or valve)
2) you have poor water flow in general (water pump etc..)
3) your thermostat is not closing properly.

The 'fresh air' heater (later Minor 1000's) is a great idea except when the outside air temp is VERY low. The best way around this is to disconnect and bung up the external intake pipe and allow the heater to heat the interior air. When the weather warms up you can just change it back to how it was intended.

(I had a red hot heater today on the M40/M42 but sadly that was due to a failing head gasket - I pulled over as soon as the heater went cold and had to wait 90 mins for the AA as I didn't have any emergency water )

[JimK]

My heater valve is knackered and doesn't allow much water to the heater. Incoming air was barely warmed, so I covered part of the intake. That way I get fresh air but at a reduced rate and warmer.

Fitting the new valve is on the list of things to do one day...

[minor_hickup]

I've blanked off 2/3rds of my radiator with cardboard painted black. The radiator is new and very efficient so warm up times can be long without the blanking. As for contingency, I have a Kenlowe fan on the unblocked part of the radiator, essential for heavy town work on milder day or the start/end of winter.

[Rob_Jennings]

I blank out about 1/3 and left the oil cooler free (which is fitted just in front of the rad).

At least I did when it dipped below zero a few weeks ago, but removed it because its still too warm down here!

[MikeNash]

One advantage, Paul, of reducing cooling air thro' the rad is that the water return from the rad will be warmer. Its probably not a Good Thing for it to return to the block too cold -the only work on this I've seen was on aero-engines where they worried (I think - its so long ago!) about distortion and condensation in the bottom of the cylinders.
If you want to try a blank, try a piece of hardboard slipped down in front of the rad with a 12 inch dia circle cut out that lines up with the fan. I've used this throughout the winter, ie Nov to Easter, even going down to a 10 inch circle when really cold. But I feel you need a temp gauge to be safe with the latter. Holes like these have the advantage that if stuck in traffic in a unexpected warm spell the only active piece, the fan, can still do its job.
Their only disadavantage is that they get in the way of the starting handle! Regards, MikeN.

[eastona]

How do I post pictures?

[rayofleamington]

One advantage, Paul, of reducing cooling air thro' the rad is that the water return from the rad will be warmer. Its probably not a Good Thing for it to return to the block too cold

The Minor was designed (and proven) based on the rad returning cooled water.
For a better heater, the safe solution is to change to a higher temp thermostat (this still allows regulation of engine temperature) and/or the option of having an improved heater matrix.

Making the radiator much less efficient so that the thermostat can no longer keep the coolant temperature down, is something that has been done since before I was born. The success rate has never been great with the occasional overheating (often spectacular!) that will happen to some that try it.
Without a temperature gauge, some folks only find out that they have boiled dry when there is a bad smell (paint burning off the engine.). Fortunately most people know about it sooner than that.

[MikeNash]

Rein,
Just done a test run watching the temp guage. (I've got the capillary type thermometer in the heater supply pipe. It been checked against a quality mercury thermo, and IMO the position in the pipe gives more useful figures than in the block.) A 88C thermostat is fitted. The heater was turned off throughout.
With no blank fitted and starting from cold in an air temp of 8C, at three miles on the flat at 30-35mph (country lanes) we'd reached 82C. Over the total of 11 miles and up to 45 mph we'd reached 88C a couple of times after which the temp fell again to around 82C. I interpret that as the thermostat only occasionally opening fully.
With a blank fitted with a 12 inch dia hole (fan sized) and now starting with a warm engine the car did the same circuit but with a home dash at around 50 mph up a mile long 150 foot climb - so as to be pulling steadily. Generally, 88C was the norm except in town or at lights when it fell to around 85C, but on the last climb it rose to 100C. (No boiling occurred - I think that's at 105C with the 4lb/sg in rad cap.)
All in all, this blank is just the job ON MY CAR for shopping etc, but I as I'd expect, too restrictive if I'm in a hurry. But know from past experience its OK if the air is really cold, say below 5C.
The oil temp at the end of each run was 62C - a bit low, what? (Measured by dropping a thermo down the dipstick hole.)
So Rein, fit a good thermometer and have fun! Regards, MikeN.
PS Anyone got experience of a 91C thermostat?
And Ray, got any pointers to the research on the rad return temps? that sounds interesting.

[Pyoor_Kate]

I find that in winter, my mog rarely gets up to 'working temperature' without blanking off the grille - so normally I cover about half of it (the half with the air intake for the interior fan, actually) with tin foil.

Doing that, the temperature guage still won't hit 88 (which is what my thermostat is set to), not unless you have that special kind of motorway traffic jam that allows it to get a bit warm. But it'll get most of the way there...

And the heater's still drawing in fresh air from the outside, but there's a bit less forced air coming through it - which keeps the car warmer without it getting too stuffy....

[rayofleamington]

Over the total of 11 miles and up to 45 mph we'd reached 88C a couple of times after which the temp fell again to around 82C. I interpret that as the thermostat only occasionally opening fully.

That sounds just perfect - when the thermostat is partially open is when you'll get the most flow to the heater. As the thermostat opens more the flow goes mainly through the radiator (although the water is hotter).
When the thermostat is throttling the flow, the engine IS up to working temperature - sadly most people think a poor heater means a cold engine, whereas on a Minor it just means that the fresh air intake is very cold to start with, and the heater matrix was rather limited even before it had 40 years of decay.

MikeNash,
It would be interesting to see what temperatures you get on the return pipe from the interior heater rather than too it, although as you can get your engine coolant well over 100, I expect this more than compensated for the reduced flow to the heater.

As for water coming from the block at 100°C - this would indicate probably 110 to maybe 120°c at some places around the system. The water will be making little bubbles at the hottest surfaces, and turning back to water when mixed with the rst of the coolant. Rather like watching a pan of water approaching boiling on a gas stove - the bottom surface can be above boiling, hence lots of little bubbles, but none of these reach the surface as the rest of the water is cooler.
At these surfaces in an engine, scale will build up gradually (or more quickly if you run on clean water without inhibitor).

For the 54 Minor I had last year, I nicked the aftermarket gold round heater from my 56 special. This heater was phenominal, and on a minus 10°C morning it melted the ice of the REAR screen and demisted the whole car within a few miles (near Burgos in Northern Spain).
If only I'd known it would be so good I'd never have let that heater go with the car. It was the type that had a pair of (manual) flaps on the front so you could allow airflow to either or both of the front footwells.

[Onne]

My car always goes to 88 degrees, and stays there on the gauge.