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Change thermostat/heater pipe head bolts
Posted: Wed Sep 27, 2023 7:54 am
by svenedin
I have been working on changing my cylinder head and head gasket.
I have a later car that has the copper heater return pipe routed on the spark plug side of the engine. The pipe has 2 brackets attached to the studs that secure the head to the block. The pipe completely obstructs removal of the thermostat housing. To change the thermostat 2x head stud nuts must be removed to remove the heater return pipe.
Some owners like to swap the thermostat twice a year and use an 88 degree C thermostat in the winter. To do this on my car would mean disturbing 2 head nuts each time.
My question is does this really matter? To change a thermostat a partial coolant drain is needed first and then only 2 head studs disturbed which can be re-torqued appropriately.
I am puzzled as to why BMC swapped the side of the engine the heater pipe runs on. Earlier cars have the pipe on the manifold side (pipe is a different shape) and secured onto manifold studs.
Stephen
Re: Change thermostat/heater pipe head bolts
Posted: Wed Sep 27, 2023 10:25 am
by unclealec
I might be talking out of my expletive deleted, but my failing memory tells me that I have in the past seen such an arrangement whereby the head nut remained in torque doing its job nicely, with the addition of an additional nut above it, the pipe lugs being sandwiched between the two nuts.
In fact I may even have made special studs in order to achieve this.
Obviously one can remove the top nut and pipe without disturbing the torque setting of the head nut.
Re: Change thermostat/heater pipe head bolts
Posted: Wed Sep 27, 2023 10:32 am
by svenedin
unclealec wrote: ↑Wed Sep 27, 2023 10:25 am
I might be talking out of my expletive deleted, but my failing memory tells me that I have in the past seen such an arrangement whereby the head nut remained in torque doing its job nicely, with the addition of an additional nut above it, the pipe lugs being sandwiched between the two nuts.
In fact I may even have made special studs in order to achieve this.
Obviously one can remove the top nut and pipe without disturbing the torque setting of the head nut.
Yes you are correct. I tried that arrangement but the heater pipe was too short to make a secure connection to the bottom hose when fitted above the stud nuts. Slightly longer studs are needed to do this but it didn’t work for me.
I could get an earlier heater pipe that is fitted on the manifold studs but I am wondering whether I am worrying about an issue that doesn’t exist?!
Stephen
Re: Change thermostat/heater pipe head bolts
Posted: Wed Sep 27, 2023 11:10 am
by Sleeper
You could " knock-up" two small brackets...

- heater pipe in.jpg (1.66 MiB) Viewed 1570 times
John ;-)
Re: Change thermostat/heater pipe head bolts
Posted: Wed Sep 27, 2023 11:37 am
by oliver90owner
Some owners like to swap the thermostat twice a year and use an 88 degree C thermostat in the winter. To do this on my car would mean disturbing 2 head nuts each time.
I’ve always been fascinated by this. A total waste of time in my experience, unless the radiator is either under-sized or in need of some maintenance - and for the UK climate the Moggie radiator has always been more than adequate on the first point.
I even fitted a larger pulley on my Ford Escort water pump and never overheated it, even with a considerably hotted-up motor fitted - and used very enthusiastically.
Sleeper, is clearly on top of the issue.
Another alternative, to unnecessarily changing the thermostat twice a year, would be to fit an electric fan? (Unless a fanatic for originality, instead of practicality).
Re: Change thermostat/heater pipe head bolts
Posted: Wed Sep 27, 2023 12:10 pm
by svenedin
oliver90owner wrote: ↑Wed Sep 27, 2023 11:37 am
Some owners like to swap the thermostat twice a year and use an 88 degree C thermostat in the winter. To do this on my car would mean disturbing 2 head nuts each time.
I’ve always been fascinated by this. A total waste of time in my experience, unless the radiator is either under-sized or in need of some maintenance - and for the UK climate the Moggie radiator has always been more than adequate on the first point.
I even fitted a larger pulley on my Ford Escort water pump and never overheated it, even with a considerably hotted-up motor fitted - and used very enthusiastically.
Sleeper, is clearly on top of the issue.
Another alternative, to unnecessarily changing the thermostat twice a year, would be to fit an electric fan? (Unless a fanatic for originality, instead of practicality).
I am a bit of an originality fan but hopefully not a total fanatic. It’s not overheating in Summer but underheating in winter that is the issue. A radiator blind would work if I could find a period part. The Morris Minor is rather over-cooled if everything is working correctly.
Stephen
Re: Change thermostat/heater pipe head bolts
Posted: Wed Sep 27, 2023 12:11 pm
by myoldjalopy
Agreed - a standard Minor in good fettle should not really require swapping of thermostats from winter to summer.
Sleeper's arrangement is a good one. On my SII, however, the heater hose runs from the bottom of the rad along the engine bay floor, held by clips, so that it goes nowhere near the head nuts
or manifold

Re: Change thermostat/heater pipe head bolts
Posted: Fri Sep 29, 2023 5:24 pm
by Bill_qaz
Is the earlier a straight swap or does your pcv get in the way?

- 20230622_155206.jpg (1.29 MiB) Viewed 1474 times
Re: Change thermostat/heater pipe head bolts
Posted: Fri Sep 29, 2023 6:17 pm
by myoldjalopy
unclealec wrote: ↑Wed Sep 27, 2023 10:25 am
I might be talking out of my expletive deleted, but my failing memory tells me that I have in the past seen such an arrangement whereby the head nut remained in torque doing its job nicely, with the addition of an additional nut above it, the pipe lugs being sandwiched between the two nuts.
In fact I may even have made special studs in order to achieve this.
Obviously one can remove the top nut and pipe without disturbing the torque setting of the head nut.
Same arrangement on my car - except it is to hold the engine steady bar, not the heater pipe which, as I previously stated, runs along the engine bay floor.