Morris Minor Owners Club

I am just thinking about fitting a heater that will give a higher output and know that some suppliers will do a full heater pretty much ready fit but have seen an uprated matrix that BM seem to do. Has anyone used the uprated matrix and is it OK or should I just go for the full kit?
Thanks Jeff.

My only experience Jeff is with using a Mini matrix and fan - the matrix is just the same (newer obviously!) but the fan is a lot more powerful. This combo (basically a complete Mini heater but fitted with a Minor front panel - so it looks as it should) results in much better flow of hot air as long as the engine is revving. Sitting in traffic at idle there is not sufficient water flow through the matrix to keep up with the fan and so it soon blows cold. A larger matrix won't help with that - what does help is a toasty 88 degree thermostat - and removal of the ghastly little water pump by-pass hose ensures a much faster flow of warm water into the heater from a cold start!

Forgive my ignorance of fluid dynamics but if you divided each pipe leading to the heater would the water pressure still be sufficient to supply two heaters? The second one could sit under the passenger glove box, maybe?

Forgive my ignorance of fluid dynamics but if you divided each pipe leading to the heater would the water pressure still be sufficient to supply two heaters? The second one could sit under the passenger glove box, maybe?

erm, yes and no!

If you increased the outlet size on the head and ran 2 pipes (or one bigger pipe) the limiting factor would be the capability of the waterpump at idle. You would get more heat at idle than with one heater but the flow rate would be the limit, so I'm not sure if that would be a bit more or double!
Running under load (higher engine speed) you would get twice the heat into the car... When more heat is taken by the interior heater(s), the thermostat will restrict what goes to the main radiator.

The Metro arrangement used a sandwich plate at the thermostat housing to supply the heater - so you could certainly take another pipe from there to a second heater - and dump it back into the bottom hose with a T piece. In days gone (yawnnnnnnnn) I used aheater from an Austin 1100 in my Mini - that had a much bigger exchanger and a very much bigger fan - certainly produced the heat when running - but again fell away quickly in traffic unless intentionally revving up from time to time to circulate the water. It did a good enough job that in winter I ran the Mini with no cooling fan!

The reason I suggested this is because I have always found the heat output in a Minor quite adequate with both the old style round Smiths type and the newer oblong thingie. What lets it down in IMO is in it's ability to circulate that warm air.
Two heaters = twice the ability. You could even route the screen vents to point at the side windows!

The answer then lies in the Mini heater which has that much larger 'two barrel' fan - and so blows the air around much more effectively! Simply remove the Mini front cover - and fit the Minor cover instead - and it looks identical!

I've never seen one of these mini heaters. Every one I've seen has a horizontal slider not vertical like a Minor.

Which is why you remove that front cover with horizontal slider - and fit the Minor one - it goes straight on!

If the biggest problem is the limited water flow from the pump at tickover would an electric pump, maybe just in heater circuit, help ?
The 400 series Volvo turbo's had an electric pump to circulate water after engine was turned off for a short while - I assume to avoid localised heat build up.
The electric pump can be found by following the water pipes from the rad on the nearside of the car.
An idea would be to add such an electric pump that could be switched on when driving in traffic.

Paul Humphries

It's hardly a problem - unless you spend lots of time idling in traffic!

as some of you know i fitted a supra heater motor to mine(same as mr2 mk1). it really went on easily, and wires in absolutely fine. it is noisy, but you know the noise is doing something so it's okay! this is for a round heater matrix i might add. the good thing is, it's looks completely standard, so the purists will almost be happy!

The 400 series Volvo turbo's had an electric pump to circulate water after engine was turned off

they did indeed - although not many of those left around these days as the engine was prone to overheating and the turbo prone to seize because they routed the oil feed next to the exhaust manifold and it would block up.

Electric water pumps were fitted on some VW, Mercedes and a few other cars too. They were used on posh Mercs to give passenger heating for a long time even when the car was turned off!