Rad Pressure

  1. Regular Poster Joined: Nov 2008 Posts: 362 Saxo 1.4 Furio
    #1
    The the other day my coolant cap blew off whilst driving and was in pieces in the road. I've bought a new cap, rad flushed and refilled it. When I'm running the car the top radiator hose feels rock solid with pressure, should there be that much pressure in the system?

    Cheers
  2. Super Moderator Joined: Nov 2009 Cambridge(ish), UK. Posts: 10581 BMW 5x M50d.
    #2
    There should be quite a bit, but excessive pressure could be caused by a few things - thermostat not working correctly, blocked rad, or worst case, a head gasket failure (exhaust gas pressurising water system).

    Make sure you have coolant in the system too - water alone in there boils at a lower temperature leading to increased pressure. Pressure should be between 9psi and 12psi if you've access to a pressure test. Pressure towards (or over) 15psi would be bad.
  3. Regular Poster Joined: Nov 2008 Posts: 362 Saxo 1.4 Furio
    #3
    Okay thank you that gives me piece of mind. The coolant was clean and not burning off and my oil is clean too, no gunk under oil cap either. Next time I take it for a spin I'll watch the temps and feel the pipes to see if the thermostat is opening and warm. Hopefully it was just a dodgy cap...
  4. Established Member Joined: Sep 2010 loughborough Posts: 2229 1988 ford fiesta mk2 1.4- 2001 black saxo furio (d
    #4
    or you could have an air lock. that'll cause excessive pressure.