Morning All, went to check all the levels yesterday and noticed the expansion tank was nearly to the top of the bottle when previously it had always remained about 1/2 full. Radiator needed topping up by around a pint . Checked the cap and it looks like the seal has perished. Could this be causing the problem? I will admit I don't fully understand how the pressurised system works and have read the posts about opting for a header tank but I am hoping a new cap may do the trick ?
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hi, could well be the cap. change it and see what happens. also have a good look around all the hoses check for leaks and at the hose connections. Tim -
Hi,
The system expands under pressure when hot and water overflows into the expansion bottle ( clue is in the name), when the engine is turned off and cools the water contracts and as long as the expansion pipe into the bottle is under the water level and the rubber seals on the expansion bottle cap are good the water is siphoned back into the engine block. A new cap of the same pressure should sort it.
MickyComment
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M icky is correct
when you look at a cap the large outer seal has a stronger spring behind it to give the 20 psi opening pressure.
the small brass cap in the centre (about the size of a 5p coil) has a weak spring.
but you must ensure there are no air leaks in the hose or you will only suck air.
PhilComment
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Thanks guys much appreciated. Ordered a 20lb cap. No Ieaks I can see .. Is it safe to drive as is ?Comment
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OK to use but check the coolant before every use
PhilComment
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Thanks Phil, every time sun shines I seem to have a problem. Just come back from garage after two weeks away trying to diagnose intermittent starting problem so was hoping i could enjoy this"practical" classic...Comment
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