BX quirks

Anything about BXs
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Posts: 26
Joined: Wed Jan 31, 2007 1:59 pm
Location: Walsall UK

BX quirks

Post by soxer123 »

I reckon someone should publish a top 10 (or more) of BX quirks.

For example, not everyday, but some days after a short journey, I reckon mine is building up pressure in the rad system which after I park up is venting possibly through the filler cap.

When I saw the wet patch the other day, I took a look and could not see evidence of a direct leak, but I would say the water is running along the least lines of resistance.

It takes about three months before I get any warning lights to tell me my water level is low, so I am not worrying unduly, but it is another one of those BX quirks.

I've not had time to post the damage pics to my front end yet, but will do so as soon as time allows.
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Post by jeremy »

Are you sure you're filling it to the correct level and not overfilling it? There should be some system for determining the level and a quite large space should be left when the water level is at the top mark.

As water heats it expands and as it cools it contracts - so if you remove and replace the cap when its cold the system will be at atmospheric pressure. If you then run it till its warm - the water will expand, compressing any gas that is there. Eventually if the pressure exceeds the cap pressure gas (and water) will be expelled. Remove the cap when its hot and the pressure will be released. Let it cool and there will be no pressure again unless some gas has been introduced from somewhere (usually through the head gasket) Any steam produced through local overheating way cause pressure when hot but the steam will condense as the engine cools and cannot be a cause of residual pressure when cold.

Fresh water contains dissolved gas (the bubbles that form in a glass of water that is left standing - beer is a bit different) It will come out of solution when the water is heated and will not dissolve again - and can be the cause of a hiss when the cap is removed.