Morris Minor Owners Club

HAS ANY ONE OUT THERE MEDDLED WITH THE HEATER. MINES A 1969 VAN AND I WANT TO COMPLETLEY FLUSH THE LOT

THANKS SMEDLET

Take both pipes off the engine and flush through both ways with a hosepipe. Make sure the valve is not blocked with crud. If you don't get some heat after that, check your engine is getting warm enough. If not try a new thermostat.

Oh, and welcome to the forum!

Good advice ^^^^^

Make sure that the hose connections to the back of the heater are tight or you will end up with a footwell full of water

Don't block the hoses! It's not designed to take ~ 40 psi mains water pressure......Just flow the water through the matrix in both directions. And check water comes out of the heater valve when you open it. BTW - best to NEVER close it anyway!

THANKS FOR YOUR TIP'S, I'L LET YOU KNOW HOW I GET ON MY MY MY NEW PARTS ARRIVE. OH AND ALSO IV BEEN TOLD WITH THE OLDER CARS ITS BEST TO GET A CERTAIN SUMMER COOLANT , IS THIS RIGHT ???

THANKS SMEDLET

Just use fresh water - with some anti freeze in it.

THANKS FOR THAT

i did a full removal and complete strip down of the heater in a 1971 Traveller, as the heater was pathetic

you can do little better than to see this great video... https://www.youtube.com/watch?v=v75LjUrVaPE

i installed an 88 deg thermostat ...having found there wasn't one fitted at all !!

i disassembled the whole unit, flushed through, but decided to refit with the larger heather matrix and hoses ...new foams where needed &
resprayed the tin work ....i only wanted to do this job the once !

in reassembly I adhesive sealed the heater body end caps, and sealed off any spare holes so no escape for that wonderful hot air

flushed out the engine and rad as well, on the basis of removing ALL crud as a new heater was going back in...why re-contaminate it ?

a fiddly job, but the end result was well worth it ...the joy of hot air to the car and a respectable, if modest, flow to the screen that does actually defrost / de-mist pretty swiftly

With all due respect, from your post it may seem that the heater was OK?

Without a thermostat fitted, the engine was likely never getting anywhere near to normal working temperature, so it may not have been surprising that “the heater output was pathetic”!

Now that you have sealed the heater, do you still get heat blowing out if you set the flap leaver to off? I have a manual tap fitted on the cylinder head and sometimes its a bit of a pain to have to stop mid journey and adjust the water flow.

the missing thermostat only part of the problem. the silted up matrix i believe the most significant defect, and after 50 years the foams had perished

with the unit all sealed up now and new foam, there is hardly any air escaping when the flap is to the 'off' position
i believe it is a bit of a design thing that when the flap is in 'screen' position there is still a bit of blow by into the car, but liveable
i have the cable controlled valve ...maybe worth the change from the manual one perhaps ?

If the thermostat is not fitted the coolant does not get pushed by the water pump to the back of the block and into the heater - it just gets circulated out of the top hose into the radiator header tank. A healthy flow of coolant through the heater matrix will ensure that sediment in the matrix is kept to the minimum as the action of flowing coolant flushes the matrix.
It is most important that the thermostat or a restrictor is installed otherwise the rear of the head can get excessively hot.

The radiators in my house are nicely balanced flow-wise. I do not open them up more if we need more heat in the winter - I increase the boiler temperature a bit thus raising the radiator temperature and increasing the heat delivered.

I have experienced, so very often, where “the symptoms are treated instead of the disease”. I truly think your heater was one of these as you would never get any heat from it if only cold water was passing, so clearly less than optimum if the engine was over-cooled (especially so when the heater output would be required).

But, never mind, you have clearly sorted the problem by actually fitting an engine thermostat - and further improved the earlier heater output by fitting a ‘heather’ matrix, whatever that might be.

I would add that an 88 Celsius thermostat would have significantly improved the heater output over the 82 Celsius version (had one been fitted).

I first realised I had a problem with a thermostat in my car when the car was not quite running as well as normal - and the heater was blowing cold air on one cold morning. This was about 50 years ago. I’ve not forgotten that experience. Soon sorted and heater and engine performance was recovered. Fuel economy also dramatically improved afterwards!!

Latter years, problems have arisen due to thermostats failing in the closed position. Now that is when one realises how much extra heat one can extract via the heater at really high engine temperatures.

Vintage tractors were often fitted with an adjustable radiator blind to enable the operator to maintain the engine at a good working temperature. Our (new) tractor was fitted with a modified header manifold about 1950-1952 (I guess) to convert it to thermostat control. Much less hassle, although the blind was still usually raised to reduce the cold air blast being blown over the exhaust and inlet manifolds - thus hastening initial manifold warming - to facilitate early change-over from petrol to the less volatile TVO fuel.

" But, never mind, you have clearly sorted the problem by actually fitting an engine thermostat - and further improved the earlier heater output by fitting a ‘heather’ matrix, whatever that might be."
I'll wager it is a misspelling of 'heater'..........