Morris Minor Owners Club

i recently had to have a replacement hose from the rad to the heater, as the old one was perished. the heater, an old smiths type, worked ok, as well as morris heaters ever do, but since the change of hose there is scarcely any heat at all. a chum suggested there may be an air lock. is this the probable cause? and if so, any recommendations to fix it?

The best way is to release the return hose and extend it in some way so that it can be placed over the open filler hole of the radiator. If you now run the engine you should see the water flowing out but with lots of bubbles if there is an air lock. Keep running until there are no bubbles,
remove the extension piece, put your thumb over the return pipe and refit it to its proper junction immediately. This worked for me.

hi willie,
if i've got this right, i unclip the hose from the pipe at the bottom of the radiator, run the engine until the water flows out of the end of the hose without any bubbles, and then re-attach. ?

Pretty much, except don't let so much water out that it stops pumping. If you don't want to bother with an extension pipe you might want to run the coolant into a bucket under the car, and pour it back into the radiator afterwards.

sorry to be so dim, lads. but when i take the hose off the pipe at the bottom of the radiator, water just gushes out of the pipe, and not the hose. so not quite sure what to do.

In this picture I've just got a single hose in place of the heater. The return pipe connects to a fixed copper pipe which runs down to the bottom heater hose. (some cars seem to have this in a different place). When I was bleeding my heater matrix I removed the return hose at the top of the copper pipe where I've drawn a circle on the picture.

NO NO NO, the return half inch hose from the heater would normally join to a small bore metal pipe which then goes forward to join the bottom heater hose. You would release the rubber pipe from where it first joins this small bore pipe and then extend the rubber pipe to flow into the radiator filler hole. ( this is purely to ensure that any water pumped out goes back into the rad so that it doesn't run dry). You do not disturb the bottom rad hose in any way. When you separate the heater hose/metal pipe joint you should also plug the metal pipe to stop water issuing from there too. (To make a plug for this is used two inches of old 1/2"heater hose blocked at one end with a wooden dowel which is then easy to slip over the end of the small bore tube). ALEXs pic shows where to do it.

Alex, i have never seen the air filter in your position, should be cooler intake for the warmer days. the rubber pipe would appear to have a right angled bend in it, is is from a particular make of car please?

Willie wrote:the rubber pipe would appear to have a right angled bend in it, is is from a particular make of car please?

ESM sell it.

Thanks.....ordered.