Minimising air locks when fitting heater matrix

Bullnose75 · 24th January 2019, 08:26

What's the best way of minimising air locks in cooling system when changing heater matrix ? Don't want to drain whole system if I can help it !
Rover has recently had new water pump and new coolant fitted by Lates with his vacuum gizmo,when he did cam belts for me,so at mo know I have no air locks in system.
Would this work ?
Am planning to clamp heater matrix rubber flow and return hoses shut under bonnet when I replace heater matrix to save draining whole system of coolant. Noticed the upper rubber hose from heater matrix runs behind battery box under bonnet and there is a join in pipe there.
So after new heater matrix is fitted i'm thinking of removing battery and battery box to get to the join in upper heater matrix pipework,leave rubber heater hose radiator side clamped off and,before unclamping lower heater rubber hose,remove the other upper rubber heater hose(the one that comes from top of heater matrix) from the join behind battery box,hold hose vertical and slowly top up new heater matrix through this hose. In theory,by gravity,new heater matrix and upper hose should then be pretty much free of air. Then,refit hose to pipe join behind battery box,release hose clamps from top and bottom heater hoses and there shouldn't be much,if any air in cooling system.
Maybe undo and hold header tank up in the air when I first start engine too.
Paul

vitesse · 24th January 2019, 09:02

Sounds a bit complicated and while I understand your wish to minimise the chances of an air lock, I don’t think you can avoid getting some air in the system. However if you bleed it correctly and continue to monitor the temperature as you are doing all should be fine.

My latest KV6 defeated the professionals https://the75andztclub.co.uk/forum/s....php?p=2690481 who had vacuum bled but still not managed to clear the airlock. I can only assume that they didn’t know about raising the expansion tank which is a bit odd but old school.

I was talking to an ex-scrapyard owner yesterday who told me that Renault used to have a problem too with bleeding and remembered using a very large water bottle suspended from the garage ceiling plumbed into the coolant system, using gravity and the weight of water to eject air.

Good luck, it’ll be worth all the effort when you get really hot air out of the heater.

Mike

ps. Love the Firebird, my son had one too until he made the mistake of getting married

SD1too · 24th January 2019, 19:29

Quote:

Originally Posted by Bullnose75

What's the best way of minimising air locks in cooling system when changing heater matrix ?

Follow the official MG Rover procedure here.

Quote:

Don't want to drain whole system if I can help it !

Why not Paul? There's nothing to be afraid of. I have always drained my cooling system fully and refilled according to the procedure above and I've never had any air lock problems. Just follow the instructions and you'll be fine.

Simon

24th January 2019, 08:26	#1
Bullnose75 Avid contributor Rover 75 Tourer 2.0 V6 LPG Join Date: Apr 2018 Location: Colchester Posts: 210 Thanks: 4 Thanked 50 Times in 39 Posts	Minimising air locks when fitting heater matrix What's the best way of minimising air locks in cooling system when changing heater matrix ? Don't want to drain whole system if I can help it ! Rover has recently had new water pump and new coolant fitted by Lates with his vacuum gizmo,when he did cam belts for me,so at mo know I have no air locks in system. Would this work ? Am planning to clamp heater matrix rubber flow and return hoses shut under bonnet when I replace heater matrix to save draining whole system of coolant. Noticed the upper rubber hose from heater matrix runs behind battery box under bonnet and there is a join in pipe there. So after new heater matrix is fitted i'm thinking of removing battery and battery box to get to the join in upper heater matrix pipework,leave rubber heater hose radiator side clamped off and,before unclamping lower heater rubber hose,remove the other upper rubber heater hose(the one that comes from top of heater matrix) from the join behind battery box,hold hose vertical and slowly top up new heater matrix through this hose. In theory,by gravity,new heater matrix and upper hose should then be pretty much free of air. Then,refit hose to pipe join behind battery box,release hose clamps from top and bottom heater hoses and there shouldn't be much,if any air in cooling system. Maybe undo and hold header tank up in the air when I first start engine too. Paul

24th January 2019, 09:02	#2
vitesse I really should get out more....... Rover 75 Saloon Join Date: Jul 2011 Location: Gävle Posts: 2,533 Thanks: 395 Thanked 823 Times in 652 Posts	Sounds a bit complicated and while I understand your wish to minimise the chances of an air lock, I don’t think you can avoid getting some air in the system. However if you bleed it correctly and continue to monitor the temperature as you are doing all should be fine. My latest KV6 defeated the professionals https://the75andztclub.co.uk/forum/s....php?p=2690481 who had vacuum bled but still not managed to clear the airlock. I can only assume that they didn’t know about raising the expansion tank which is a bit odd but old school. I was talking to an ex-scrapyard owner yesterday who told me that Renault used to have a problem too with bleeding and remembered using a very large water bottle suspended from the garage ceiling plumbed into the coolant system, using gravity and the weight of water to eject air. Good luck, it’ll be worth all the effort when you get really hot air out of the heater. Mike ps. Love the Firebird, my son had one too until he made the mistake of getting married