Replacing coolant flanges

[james butler]

good shout putting the part numbers up rosie
i put hylomar on the mounting surface of the head before bolting up flanges as they are prone to leaking when heat cylcling
this is especially noticeable on the thermostat housing
hopefully you wont have any issues now though

[rosie]

Thanks. I’ve done 20 miles or so in it and no leaks from the flanges or sensors now so hopefully they’re watertight.
However the thin hose from the expansion tank to the top of the radiator has now sprung a leak. I’ve just ordered a new one. Is it possible to swap this without draining the system? I’m getting through a LOT of coolant!

[GT_II]

Draining down the coolant would be an overkill, but you will get a minor spillage. Disconnect at the expansion tank end first, tie it up to the bonnet while still connected to the radiator. Connect the new hose to the expansion tank, then quickly swap over the hoses at the radiator end. Then run the engine with the heater on to bleed the system as normal.

[mark1gls]

Yes no need to drain the coolant for the thin expansion tank feeder hose.

Just go carefully with the plastic pipe on the radiator and try pull the hose off straight as I’ve snapped one off before and had to buy a new radiator…

[GT_II]

pull the hose off straight as I’ve snapped one off before and had to buy a new radiator…

Good point, also before you pull, gently twist the hose to and fro over the nozzle with a pair of pliers to release its adhesion to the nozzle. Once you've done this, It's often easier to carefully push the hose off the nozzle than to pull it, as pulling the hose will tend to stretch and narrow it. Experience gained from years of removing hoses from plastic nozzles within washing machines, dishwashers, etc, but I'm guessing just as relevant to cars.

[rosie]

Thank you!
MoT this afternoon, so will wait until afterwards just in case something snaps.

[james butler]

pull the hose off straight as I’ve snapped one off before and had to buy a new radiator…

Good point, also before you pull, gently twist the hose to and fro over the nozzle with a pair of pliers to release its adhesion to the nozzle. Once you've done this, It's often easier to carefully push the hose off the nozzle than to pull it, as pulling the hose will tend to stretch and narrow it. Experience gained from years of removing hoses from plastic nozzles within washing machines, dishwashers, etc, but I'm guessing just as relevant to cars.

this is why i tend to slit the old pipe with a knife and spread it open so as to put as little pressure on the rad nipple as possible