Liquid flowing after shutting off car
Username
Do you already have an account?
Forgot your password?
  • Log in or Sign up

    Results 1 to 10 of 10
    1. #1

      Liquid flowing after shutting off car

      Hi Everyone,

      When I shut down the car, there is still some liquid moving through pipes near the back of the engine bay. It is loud enough to hear outdoors even when the hood is closed. At first I thought it was more of a hissing (like a leaking coolant pipe), but it seems to be more like a flowing liquid sound. It doesn't sound like a typical 'cooling off' noise. Any ideas what this might be?
      2007 Volvo S40 T5 AWD Geartronic - Passion Red

    2. Remove Advertisements

      Advertisements
       

    3. #2
      When did you last did anything with your coolant?

      I suspect that there is an air pocket somewhere and it's going to blow soon. Try bleeding the air from it


      Sent from my iPhone using Tapatalk
      2008 Passion Red C30 6 Speed M/T
      V1 with Preferred, Climate Package and Dynaudio.
      Added: R Design Spoiler+Steering Wheel+Knob, K&N Air Filter Replacement, EuroSport Tuning Strut Bar, Borla CBE, Vibratechnics Rear Engine Mount, Forge Recirculation Valve, IPD Skidplate, KW V3

    4. #3
      The only liquid systems in the rear of the engine bay are:

      Turbo Coolant Lines
      Heater Core Lines
      AC Compressor lines
      The coolant expansion reservoir

      As long as your coolant level is not dropping then you're not losing coolant.
      Last edited by avenger09123; 03-18-2017 at 01:20 PM.
      2006 Volvo S40 AWD T5 M66 - Dusty Rusty
      2012 Subaru Outback 2.5i CVT - Slowmobile - CAI only, Powerstop Rotors+Pads.
      1996 HD Electra Glide - Big Bertha 10:1 Pistons; EV13 Cam: Ultima Digital Ignition; Buell Head Conversion; E85 Carb Tuned;

    5. Remove Advertisements

      Advertisements
       

    6. #4
      Thanks for the replies.

      What's the best way to bleed air from the system?

      I noticed that the coolant level had dropped ever so slightly below the MIN level marker. I topped up with distilled water to slightly above the MAX line. I read that it won't hurt the system to be slightly overfull. I saw some drops coming out near the petcock, and suspect I have a slow leak there.
      2007 Volvo S40 T5 AWD Geartronic - Passion Red

    7. #5
      So the coolant system is designed to operate with 15psi of air pressure when at operating temp. It more than likely will not blow anything along the way. Since liquid doesn't compress, if your 15psi vent cap on the top of your coolant reservoir is functioning properly, the only pressure in the system is going to be the standard 15psi, any more is going to vent out through that cap. If your reservoir fills all the way up then you know you have an air pocket that is expanding somewhere pushing coolant up into the reservoir, but considering your level is dropping and not rising you bet your butt you have a crack somewhere adn that water is boiling off.

      Considering you hear water running sounds, that is an indication you have a leak and air is being introduced back into the system since that is how running water makes noises, either vibrating pipes or direct exposure to some air somewhere.

      Bleeding the system in a car like this is pretty simple, just ensure there are no hydrolocks in the radiator by squeeze each of the rubber hoses for the radiator and check for dried coolant where it's leaking and the water boiled off looking like some blue/white or green/white powder.
      Last edited by avenger09123; 03-18-2017 at 09:18 PM.
      2006 Volvo S40 AWD T5 M66 - Dusty Rusty
      2012 Subaru Outback 2.5i CVT - Slowmobile - CAI only, Powerstop Rotors+Pads.
      1996 HD Electra Glide - Big Bertha 10:1 Pistons; EV13 Cam: Ultima Digital Ignition; Buell Head Conversion; E85 Carb Tuned;

    8. #6
      Another way to bleed air is to turn on the fan to max and heat to max. Open the overflow cap and just wait for the coolant level to drop. When it does, it's an air pocket leaving. So add more coolant. Process should take 15 min to 30 min


      Sent from my iPhone using Tapatalk
      2008 Passion Red C30 6 Speed M/T
      V1 with Preferred, Climate Package and Dynaudio.
      Added: R Design Spoiler+Steering Wheel+Knob, K&N Air Filter Replacement, EuroSport Tuning Strut Bar, Borla CBE, Vibratechnics Rear Engine Mount, Forge Recirculation Valve, IPD Skidplate, KW V3

    9. #7
      Member EngTech's Avatar
      Join Date
      Jan 2007
      Location
      Knight's of the Round Table - TN
      Posts
      7,724
      Miles on Motor , Coolant Changed When ?
      Any Air getting into System - Is Not Good at All !

      Please make a Sound Video . .
      ** V50 AWD - Handling & Performance Tweaks = New Stance / VW CC - Handling Tweaks - Testing & Porting - Intake Mods
      A Garden Gate will Last You a Life Time . http://s261.photobucket.com/user/Eng...0Trim%20%20etc

    10. #8
      Junior Member JeremyR's Avatar
      Join Date
      Dec 2016
      Location
      Oregon, IL
      Posts
      73
      Are you running the a/c or defroster?
      Hissing is a common a/c problem noise in cars. I think the expansion valve or something usually.

    11. #9
      A/C / defroster are off, and the sound is heard after the car is shut off.

      73k miles on the car/engine. Fluid has never been replaced to my knowledge. Got the car at 70k miles. Was planning to flush the fluid at the 75k service.

      I'll try squeezing all the coolant lines, and then do JN2k's suggested bleed procedure.
      2007 Volvo S40 T5 AWD Geartronic - Passion Red

    12. #10
      After trying JNK2k's suggestion, it didn't seem like any air was burped out but the car hasn't made the sound after a couple of decently long rides. It was only doing it when the coolant was up to temp before.
      2007 Volvo S40 T5 AWD Geartronic - Passion Red

    13. Remove Advertisements

      Advertisements