Coolant pressure low?

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paul13899
E30 Zone Newbie
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Location: Merseyside

Post Tue Feb 12, 2013 9:29 pm

Hey guys,

I replaced my leaky radiator today for an aftermarket one from eurocar parts..

Everything was very straight forward, heater blows hot air, car doesnt over heat and there is circulation.. the query is.. when i was "massaging" the top hose to get the air out, i could hear a hissing noise from the expansion cap as the coolant level rose upand down.. is this normal or is my cap leaky?

Cheers.
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milescook
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Post Tue Feb 12, 2013 9:36 pm

Coolant cap on really tight? Sorry if its a bit obvious but the cap has to be dead tight!
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paul13899
E30 Zone Newbie
E30 Zone Newbie
Posts: 123
Joined: Sun Jan 13, 2013 11:00 pm
Location: Merseyside

Post Tue Feb 12, 2013 9:44 pm

Its as tight as i can possibly go with my hand + a rag. Are we talking like get a pair of pump pliers tight maybe? its not overheating or anything just a bit weird :/
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Brianmoooore
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Post Tue Feb 12, 2013 11:57 pm

If you're massaging the pipes with zero pressure in the system, it might just be the valve in the cap that lets air in when the system cools. As soon as pressure starts to build up, this valve is held shut, and the system is sealed until the pressure opens the pressure release valve.
Does the pressure build up eventually? If not, check that the lower O ring around the side of the cap is intact. If your E30 uses a 1.4 bar cap (everything except the iS and M10), check that it's been replaced under the 1996 safety recall.