Your browser isn't supported
It looks like you're using an old web browser. To get the most out of the site and to ensure guides display correctly, we suggest upgrading your browser now. Download the latest:

Welcome to the MSE Forums

We're home to a fantastic community of MoneySavers but anyone can post. Please exercise caution & report spam, illegal, offensive or libellous posts/messages: click "report" or email forumteam@. Skimlinks & other affiliated links are turned on

Search
  • FIRST POST
    • Danny G
    • By Danny G 14th Feb 18, 11:02 AM
    • 601Posts
    • 25Thanks
    Danny G
    Radiator & hose cold,but Fans are turning on HELP!
    • #1
    • 14th Feb 18, 11:02 AM
    Radiator & hose cold,but Fans are turning on HELP! 14th Feb 18 at 11:02 AM
    CAR Sear Leon, 2007, Petrol Manual


    When driving around,

    Temp gauge: Stays on 90 (Doesn't increase)

    Inside heater works fine, blows out hot air


    Hose 1 going from thermostat to the radiator is cold


    Hose 2 is hot.



    So while hose 2 is cold (thermostat hose) and the front radiator is cold..

    the fans at the front of the engine start going on,
    after temp reaches 90, but while the radiator is cold!

    so the fans are blowing a cold (non heated) radiator)


    What does this sound like?
    No Unapproved or Personal links in signatures please - FT3
Page 1
    • roneik
    • By roneik 14th Feb 18, 2:24 PM
    • 137 Posts
    • 51 Thanks
    roneik
    • #2
    • 14th Feb 18, 2:24 PM
    • #2
    • 14th Feb 18, 2:24 PM
    Replace thermostat
    • Tarambor
    • By Tarambor 14th Feb 18, 2:53 PM
    • 2,847 Posts
    • 2,059 Thanks
    Tarambor
    • #3
    • 14th Feb 18, 2:53 PM
    • #3
    • 14th Feb 18, 2:53 PM
    +1 thermostat is stuck. What it should be is the top hose from the thermostat to the radiator should be hot, the bottom one cooler or cold. Radiator is cold because the water isn't circulating. Bottom hose is hot because the water isn't circulating so the water lower down is getting hot as well (remember heat rises).

    Fans are coming on because the water where the fan thermostatic switch is is far hotter than the water in the cylinder head where the temperature gauge sensor is.
    • AdrianC
    • By AdrianC 14th Feb 18, 3:22 PM
    • 17,377 Posts
    • 15,714 Thanks
    AdrianC
    • #4
    • 14th Feb 18, 3:22 PM
    • #4
    • 14th Feb 18, 3:22 PM
    Check the fan switch.

    Or... does the car have aircon? Quite often, fans work all the time the aircon's on - to keep air moving over the evaporator, which is mounted with the rad.
    • oldagetraveller
    • By oldagetraveller 14th Feb 18, 3:37 PM
    • 3,097 Posts
    • 1,608 Thanks
    oldagetraveller
    • #5
    • 14th Feb 18, 3:37 PM
    • #5
    • 14th Feb 18, 3:37 PM
    "the evaporator," Condensor.
    Did you hear about the politician who had a backside transplant? It rejected him.
    • AdrianC
    • By AdrianC 14th Feb 18, 4:02 PM
    • 17,377 Posts
    • 15,714 Thanks
    AdrianC
    • #6
    • 14th Feb 18, 4:02 PM
    • #6
    • 14th Feb 18, 4:02 PM
    "the evaporator," Condensor.
    Originally posted by oldagetraveller
    D'oh. You are, of course, right. The evap is inside the dash.
    • Danny G
    • By Danny G 15th Feb 18, 1:19 AM
    • 601 Posts
    • 25 Thanks
    Danny G
    • #7
    • 15th Feb 18, 1:19 AM
    • #7
    • 15th Feb 18, 1:19 AM
    UPDATE: Bleeding done!

    (Air con has Not on during the whole time this test has been done)



    I Bled the system by this way:

    Coolant cap off, tiny air bubbles were coming in the coolant cap visibly, then after reving the accelerator
    a huge volcano of coolant came out of the coolant tank and leaked out everywhere, which was a surge of air (perhaps an air pocket was there and escaped right?).


    Result?
    and both hoses seem hot now (well one a bit cooler than the other, but still warm.

    but the radiator still seems to feel cold.


    Driving with heater on max!
    but one thing is that, when driving around for 30 minutes with the inside heater on maximum hot,

    then when stopping the car to feel the hoses then the hose which was originally cold, is still cold, and the other hose hot.


    so when driving with the car temperature heater on max hot, that causes that thermostat to stay cold,


    1) is that normal? shouldn't both hoses be warm?
    with the internal heater on maximum hot?

    2) Why if both hoses are hot, would the radiator stay cold?

    3) Could it potentially mean more air still in the system ?


    Answers to 1) 2) 3) ?? would be appreciated

    Thank you.
    Last edited by Danny G; 15-02-2018 at 2:07 AM.
    No Unapproved or Personal links in signatures please - FT3
    • Tarambor
    • By Tarambor 15th Feb 18, 7:07 AM
    • 2,847 Posts
    • 2,059 Thanks
    Tarambor
    • #8
    • 15th Feb 18, 7:07 AM
    • #8
    • 15th Feb 18, 7:07 AM
    1) It isn't normal, both hoses should be warm.

    2) The radiator isn't getting hot because of the same reason it wasn't before, the thermostat is jammed shut so coolant isn't circulating through it.

    3) Very unlikely given how long you've run it. It'll be the thermostat.
    • Norman Castle
    • By Norman Castle 15th Feb 18, 10:24 AM
    • 6,955 Posts
    • 5,720 Thanks
    Norman Castle
    • #9
    • 15th Feb 18, 10:24 AM
    • #9
    • 15th Feb 18, 10:24 AM
    1) is that normal? shouldn't both hoses be warm?
    with the internal heater on maximum hot?
    Try turning the heat and interior fan off for a few minutes. Does the radiator get warm? In cold weather the heater may be taking enough heat out of the engine for the thermostat to stay closed.

    It the radiator is cold the cooling fan shouldn't be running. If it is the small amount of heat in the radiator will be quickly cooled.

    Is it a diesel? I don't think they heat up as much as petrol cars unless working hard.
    Last edited by Norman Castle; 15-02-2018 at 10:27 AM.
    Don't harass a hippie. You'll get bad karma.

    Never trust a newbie with a rtb tale.
    • Danny G
    • By Danny G 15th Feb 18, 12:22 PM
    • 601 Posts
    • 25 Thanks
    Danny G
    Try turning the heat and interior fan off for a few minutes. Does the radiator get warm? In cold weather the heater may be taking enough heat out of the engine for the thermostat to stay closed..
    Originally posted by Norman Castle
    Done this,

    yes after turning the inside heat to COLD, and inside fan off then both hoses get hot (well the cold thermostat hose warms up) compared to before.

    so I guess the internal heater matrix was taking enough heat, causing the thermostat to stay closed as you suggested.


    ---

    otherwise which of these statements is correct?

    After driving for 30-40 minutes,
    at 30-50mph in this cold weather:

    with the inside heater is set to full heat/maximum hot, with blower on full...


    a) after 40 minutes, one hose should be boiling hot, and the 2nd hose should be warm (assuming the thermostat has opened) with the fans kicking in eventually?

    b) Both hoses boiling hot, the same temperature.
    (Thermostat opened), with the fans kicking in eventually?

    c)
    one hose should be boiling hot, and the 2nd one cold, thermostat hasn't opened,
    as the car engine gets cool by the blowing cool air, that it is driving through

    d) another scenario, regarding the hoses?,
    please state what would typically be expected to be 'felt' regarding the hoses ?, temperature, and engine fans ?
    Last edited by Danny G; 15-02-2018 at 1:05 PM.
    No Unapproved or Personal links in signatures please - FT3
    • Norman Castle
    • By Norman Castle 15th Feb 18, 2:05 PM
    • 6,955 Posts
    • 5,720 Thanks
    Norman Castle
    d, 30-50 mph presumably light load on the engine, heater on full. The heater is removing enough heat, no need for the thermostat to open or opening for minimum time sporadically.

    c) one hose should be boiling hot, and the 2nd one cold, thermostat hasn't opened,
    as the car engine gets cool by the blowing cool air, that it is driving through
    If the thermostat is closed both hoses will be cold. The thermostat is normally on the engine.
    Last edited by Norman Castle; 15-02-2018 at 2:11 PM.
    Don't harass a hippie. You'll get bad karma.

    Never trust a newbie with a rtb tale.
    • roneik
    • By roneik 15th Feb 18, 2:20 PM
    • 137 Posts
    • 51 Thanks
    roneik
    Change the thermostat

    Replace thermostat
    I told you before dont blow the doors off Arry, just change the thermostat
    Last edited by roneik; 15-02-2018 at 2:25 PM.
    • roneik
    • By roneik 15th Feb 18, 2:29 PM
    • 137 Posts
    • 51 Thanks
    roneik
    The thermostat opens when the top of engine is warm enough to trigger the wax to melt in the thermostat and allow spring to lift. Then warm water circulates through entire engine and radiator.Thats why your rad and one hose is cold. Your thermostat is jammed shut
    Last edited by roneik; 15-02-2018 at 2:32 PM.
    • Danny G
    • By Danny G 15th Feb 18, 9:58 PM
    • 601 Posts
    • 25 Thanks
    Danny G
    Norman Castle Thanks.

    one hose is hot and the other (thermostat hose) is cold.


    Another finding:
    (please view it on my other thread,

    it is what happens when the car is idle, and started for a long time, check my other thread for this finding.
    Last edited by Danny G; 15-02-2018 at 10:13 PM.
    No Unapproved or Personal links in signatures please - FT3
    • treboeth
    • By treboeth 15th Feb 18, 10:56 PM
    • 1,066 Posts
    • 1,199 Thanks
    treboeth
    Board Guides contacted for unnecessary duplication.
    • BeenThroughItAll
    • By BeenThroughItAll 16th Feb 18, 3:19 PM
    • 4,680 Posts
    • 4,092 Thanks
    BeenThroughItAll
    Are you incapable of purchasing a car which doesn't have cooling problems, OP?

    Last time it was a Peugeot wasn't it?
    • Muscle750
    • By Muscle750 16th Feb 18, 6:00 PM
    • 982 Posts
    • 300 Thanks
    Muscle750
    Rads blocked
    • arcon5
    • By arcon5 16th Feb 18, 6:28 PM
    • 13,536 Posts
    • 8,596 Thanks
    arcon5
    So what's the actual problem? am I missing something.... Your engine heats up with no fluctuation of temperature. Interior heater is working. You don't appear to have any faults..
Welcome to our new Forum!

Our aim is to save you money quickly and easily. We hope you like it!

Forum Team Contact us

Live Stats

348Posts Today

4,187Users online

Martin's Twitter
  • It's the start of mini MSE's half term. In order to be the best daddy possible, Im stopping work and going off line? https://t.co/kwjvtd75YU

  • RT @shellsince1982: @MartinSLewis thanx to your email I have just saved myself £222 by taking a SIM only deal for £7.50 a month and keeping?

  • Today's Friday twitter poll: An important question, building on yesterday's important discussions: Which is the best bit of the pizza...

  • Follow Martin