Morris Minor Owners Club

My cylinder head is out of commission due to the thermostat housing being seized on solid and the studs refusing to budge too. Whilst it is being persuaded to release by my local machine shop, I do have a spare head but it has the bypass hose connection blanked off with a plug. I can't get the plug out to replace it with an outlet connection so my question is, if I blank off the water pump connection can I use the head as is or do I need to do anything else?

Yes, just plug the connection on the water pump. I've used a solid pipe with a bolt blocking it. Either keep the heater valve open or drill 1 X 1/8" hole in the rim of the thermostat to allow a little water to circulate. To release the stat cover, apply HEAT, lots of it.

OK, thanks. Tried everything on the housing including blowtorch. Even tried a stud puller to remove the studs but one of them sheared off inside the housing hence my need to employ the services of a machine shop. They seem to be dragging their heels so I thought I'd stick the spare head on for now.

Most just smash the thermostat housing - new ones are plentiful and not expensive. Get the thing back from the 'machine shop'. You will find faster heater warm-up and better heater performance with NO bypass hose!

That's good to know. My spare head is probably better anyway in that it has been rebuilt recently but I haven't used it because the old head was performing fine and I'm a great believer in if it ain't broke, don't try to fix it. I'll blank off the water pump. Should I drill a small hole in the thermostat to allow a little flow or is it not necessary?

stuart_k wrote:That's good to know. My spare head is probably better anyway in that it has been rebuilt recently but I haven't used it because the old head was performing fine and I'm a great believer in if it ain't broke, don't try to fix it. I'll blank off the water pump. Should I drill a small hole in the thermostat to allow a little flow or is it not necessary?

One problem I had when fitting a 'non-bypass' head was the engine over heating. I think this was due to an air pocket 'jamming' the cooling system. I've got a temperature guage fitted and I would probably have never noticed until maybe the engine seized/failed.
I think the by-pass hose perhaps allows the head water jacket to fill with water and pushing the air out. My only solution was to top it fully up and 'squeeze' the hoses perioically. Whilst ofcourse trying to avoid chopping my fingers off by the fan blade, if the engine is running!
Perhaps drilling a hole in the thermostat might do it.