500bhp Posted April 16, 2009 Share Posted April 16, 2009 I have noticed that when my 1998 2.5 DSE is cold the cooling system is still pressurised, when you remove the cap on the expansion tank, is this correct, I thought it would only have pressure when hot? Quote Link to comment Share on other sites More sharing options...
steve_d Posted April 16, 2009 Share Posted April 16, 2009 Is it pressure or vacuum you're are experiencing? Steve Quote Link to comment Share on other sites More sharing options...
500bhp Posted April 16, 2009 Author Share Posted April 16, 2009 Is it pressure or vacuum you're are experiencing?Steve Definitely pressure Quote Link to comment Share on other sites More sharing options...
sheltie50 Posted April 16, 2009 Share Posted April 16, 2009 With the engine cold are you experiencing this before you start it, check before you start-up in the morning. Quote Link to comment Share on other sites More sharing options...
500bhp Posted April 17, 2009 Author Share Posted April 17, 2009 With the engine cold are you experiencing this before you start it, check before you start-up in the morning. Hi yes stone cold before I have started it, pressure is present. Quote Link to comment Share on other sites More sharing options...
ThreeSheds Posted April 17, 2009 Share Posted April 17, 2009 Well letting my thoughts run wild here since I have never heard of this before... The cap will retain a certain amount of pressure, but since it was at atmospheric when last filled/checked any pressure when hot is normally the result of heat expansion of water in the system, and any such pressure would naturally disappear when the temperature returns to normal and the fact that your doesn't means that there is something additional getting into the system from somewhere which is not able to escape through the same route later. Usual suspects are cylinder/exhaust gas, but they normally leak out again when the engine is switched off – obviously this is not happening in your case. The reason for this unusual behavior is open to speculation*, but the base reason for the problem I would suggest is the same as it would be if we were just considering over-pressurisation: head gasket, warped head, cracked head, cracked block etc and in my humble opinion, that is where you should be looking Hope this helps a bit Roger * I am imagining perhaps a bit of gasket that is free to move (like a hanging chad) and is acting as a little flap-valve... Quote Link to comment Share on other sites More sharing options...
steve_d Posted April 17, 2009 Share Posted April 17, 2009 It's a new one on me too. Have to agree that the extra pressure is coming from somewhere. Saving grace for the moment is that it can't be too big a leak or it would release the pressure when the engine cools. I think it is a waiting game but if you really feel you must do something then perhaps a run round the head bolts with a torque wrench may nip a problem in the bud. Steve Quote Link to comment Share on other sites More sharing options...
500bhp Posted April 19, 2009 Author Share Posted April 19, 2009 The reason I am a little confused is the hand book says to check levels only when cold, and to remove the cap slowly to let pressure escape, making me think it should be under pressure when cold. Below is the excert in the user manual. NEVER remove the filler cap when the engine is hot; escaping steam or scalding water could cause serious personal injury. The coolant level in the expansion tank should be checked at least weekly (more often in high mileage or arduous operating conditions). Always check the level WHEN THE SYSTEM IS COLD. Unscrew the filler cap slowly, allowing the air pressure to escape, before removing completely. Maybe someone with a P38 2.5 could check their cap for me, when cold. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.