Question about 2000 BMW 3 Series

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The water is boiling up in the header tank of my 318i and pushing back through the pressure cap,the system seems fine,no blockages,and the head gasket is fine,im at a bit of a loss,anyone got any ideas??

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Excessive preasure in cooloing system comes from 1. overheating. 2. radiator cap not releasing at prescribed preasure. Combustion gas getting into systen via head gasket failure due to overheating and cracks or pourious cylinder head. A preasure test (120 PSI) of each cylinder at TDC firing stroke will tell you for sure where to go. make sure that the radiator cap is off when you carry out this test. 120 psi will blow radiator and or hoses . Need to stop engine turning over while you carry out this proceedure. You will identify the problem.

Posted on Dec 10, 2012


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Posted on Jan 02, 2017

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SOURCE: 2001 BMW 318i se Coolant

check the cap on the coolant ,i had same prob. if the cap is loose the level of water will change.tighten the cap it can be somthing as simple as that.

Posted on Nov 03, 2008

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SOURCE: not getting heat into the car 323i bmw 1997 touring

Thermostat , ITS ABOUT $60 CHANGE IT :)

Posted on Feb 09, 2009

  • 2559 Answers

SOURCE: water escaping from radiator cap

If it is over flowing.(Over fill would leak into the overflow tank,Not out of the cap)

This can be due to:

  1. trapped air in the system.
  2. A leaky head gasket.
  3. a sticking thermostat.
  4. improper coolant/water mixture.
  5. non working fan.
  6. Faulty cap

Posted on May 05, 2009

SOURCE: Rapid overheating. New thermostat didn't fix it. Head removed... gasket ok. No apparent cracks in head. Main fan/clutch seems to work ok. Any ideas ? Mike in NZ

I know that this is going to sound like of dumb but I would check and make sure your thermostat was installed the correct way. I had a similar issue once, after replacing the entire cooling system on a 750iL it still over heated, turned out I put in the thermostat the wrong way. Always check for little mistakes first:) Hope this helps and please don't forget to rate me.

Posted on May 21, 2009

SOURCE: bmw 318i

The car's engine is overheating !
Its not because you forgot to fit in the thermostat there could be other problem, like tht of the water pump, radiator clogged up, cooling fan.
You have to check them all.
Was there any problems before you pulle out tht cylinder head?

Posted on May 25, 2009

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a few things to check before we condemn it as a leaking head gasket(pressurising water out).
First check the radiator cap seal,no cracks and that it takes some pressure to push the spring loaded part down.
Does both the top and lower radiator hose get hot as temp gets to normal(where thermostat should be open).if not,the thermostat may be a faulty one or has slipped out of seat as the cover was bolted back down onto it.(temperature will differ either side of it).I have had some of these come in with part of the waterpump impellor rotted away.same symptom of one hot and one cold hose,and water doesnt flow inside radiator with cap off(ensure this is not removed if engine is hot)and temp where the thermo should be open.
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