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dsurette's avatar
dsurette
Explorer
Sep 26, 2013

E450 brake noise

2008 Coachmen Freelander 3150SS w/2007 Ford E450 making a strange noise when braking fairly hard. With light pressure there is no problem but there is noise kind of between a groan and a hum when applying more pressure to come to a stop. The noise continues sometimes for as long as about a minute after stopping and resuming driving. Even sitting idling the noise remains and eventually goes away. I think the frequency of the noise changes with engine RPM but I'm not sure.
We're at a s&b in Oquossoc, Maine and will be here for a few days before going back to Tennessee. I will have it looked at ASAP if I can find a place that can do the work. Anybody have any ideas about what might be going on so I can know what to expect? BTW it has about 40K miles on it.
TIA
Class C
  • hotbyte's avatar
    hotbyte
    Explorer
    Sep 26, 2013
    Just a wild guess, but if sound continues even after stopped it is likely related to something with the power assist side of the brakes and not the braking components at the wheels. When you hear noise sitting/idling, are you still in drive with brakes engaged? Wonder if it would continue or stop if you shift to park and release brakes.
  • dsurette's avatar
    dsurette
    Explorer
    Sep 26, 2013
    Yes, it continues with the brakes released and even while driving. I have turned the engine off and back on and the noise remains. But never much longer than about a minute. I agree that it is probably something with the power assist.
  • SuperDutyFiver's avatar
    SuperDutyFiver
    Explorer
    Sep 26, 2013
    Definitely sounds like the booster pump-I'm wondering if your booster pump is sucking some air when under load and it's taking a little time to purge it out after it's stressed?
  • carringb's avatar
    carringb
    Explorer
    Sep 26, 2013
    Check your power steering fluid level. This is what powers your brake booster, and low PS fluid will cause it to suck air and make noise.

    If its low, double check all your lines and make sure you don't have a hose rubbing anywhere or a leaking fitting. Also double check the brake fluid to make sure the booster isn't cross-contaminating.
  • dsurette's avatar
    dsurette
    Explorer
    Sep 27, 2013
    Thanks Carringb. The PS fluid level is very low. We have to go into a bigger city (Farmington) and I'll get some MERCON ATF which Ford recommends. I'll post the results later, but I think you got it. Brake fluid is full.
  • hotbyte's avatar
    hotbyte
    Explorer
    Sep 27, 2013
    Good to know! Hope it resolves your noise and hope I can remember this if mine ever makes a noise :)
  • ron_dittmer's avatar
    ron_dittmer
    Explorer II
    Sep 27, 2013
    carringb knows his E-Series stuff.

    I was about to say....

    Unlike the E350 and a typical car with a vaccuum assist power brake booster, the E450 has a completely different hydraulic power brake system. Check that fluid, though you have brake fluid too.

    I assumed the E450 power brake pump was it's own devise, not sharing the same fluid from the power steering pump and/or reservoir. I never had an opportunity to see underhood of an E450 to see how it was actually setup.
  • carringb's avatar
    carringb
    Explorer
    Sep 27, 2013
    ron.dittmer wrote:

    I assumed the E450 power brake pump was it's own devise, not sharing the same fluid from the power steering pump and/or reservoir. I never had an opportunity to see underhood of an E450 to see how it was actually setup.


    It's just a big loop powered by the power steering pump. It goes pump-->brake booster-->steering box-->reservoir-->pump except there's an extra return loop off the brake booster, and the brake booster has an accumulator to maintain pressure for a few brake applications if hydraulic pressure from the P/S pump is lost.

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