Classic cars forum & vehicle restoration.

[MVPeters]

I've always thought that the coolant should be visible at the top of a conventional radiator. It needs to cover the top of the radiator tubes or presumably, there's no flow through the system.
& does it matter if the expansion tank is above or below the top of the rad?
Does it make any difference if you use a pressurised or non-pressurised rad cap?
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Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'

[alanb]

I had a Citroen BX that was extremely difficult to fill without getting air locks as the expansion tank was lower than the engine and radiator although it did have bleed valves in the pipe work by the heater and carburettor, the way they did it at the garage was with a large bottle that fitted over the expansion tank taking the water level above the engine and heater and then filled it with all the bleed valve s open and the engine running.
If you have air in the system then the air will expand much quicker and much more than water thus forcing the water out, the other possible cause could be a build up of pressure caused by a leaking head gasket, have you tried testing the water system for gases?
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old tourer


Morris 8 two seater

[Rootes75]

The Commer has an expansion tank approx. 12 inches above the radiator. The operators manual states that the coolant level should not be seen in the expansion tank but when she boils up the water level rises up the 12" of pipe into the expansion tank.
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Various Rootes Vehicles.

[MVPeters]

Just another thought:
You have a 'header overflow pipe' and an expansion tank. Are they connected in the right sequence? Or do you need both? I'm thinking that the overflow should be from the expansion tank, not the radiator header.
Wiki refers to the engine as a 'Commer Knocker'!
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Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'

[peter scott]

Rootes you mention that the banging "starts slow and quiet then increases in frequency and volume". If the frequency of the banging doesn't follow the engine revs then I think I would rule out the water hydraulic theory.

Peter
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http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[MVPeters]

[Rootes75]

Thanks for all your suggestions, we are going to try out lots of theories before we do anything drastic like taking the head off etc.

Its good to get ideas from everyone, we all have a different take on things and to me this is what the forum is all about.
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Various Rootes Vehicles.

[Clactonguy]

interesting thread and a lot of good suggestions . though I understand some garages can leak test engines using pressure testing ( cylinder and coolant) plus chemical tests. though not directly involved in these checks so only have word of mouth as it were. If it was my engine depending on cost /time of things would go through process of checking pressure in system and assuming we think internal coolant leak ..topping up required often? ..then would think about changing head gasket and having head checked for flatness or lightly skimmed too. is there a 'commer' forum at all? and have we bounced the issue of other sites such as 'petrol heads' .good luck and do update please so we can all find out final fix.

[ukdave2002]

leak down testers can be purchased for less than £25 these days If you have a compressor it would be worth getting one as it will quickly identify if there is a leaky cylinder and where its leaking from.

Far more informative than a compression test.




Dave