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[Vectra C] [02-08] Thermostat changed but still running cold

Discussion in 'Cavalier, Calibra, Vectra, Signum, Sintra & Insignia owners forum' started by Boris1, Jan 10, 2017.

  1. Boris1

    Boris1 Member

    Messages:
    16
    Likes Received:
    4
    Drives:
    Vectra SRI 1.9 CDTI
    2007 Vectra C 1.9cdti 183k owned from new.
    When new and for first 130k + miles ran at 90 degrees on dash (half way where it should be), then started running a bit cooler and would only reach 80-85, simples me thinks and had a genuine Vauxhall thermostat fitted - having had the new thermostat fitted it runs even cooler infact the gauge doesn't even register in cold weather or after a 170mile non stop trip!!!
    Hidden temp shows it is continually tuning 68-69 degrees??
    Any ideas please - Vauxhall saying it must still be thermostat (out of warranty now with guy that fitted it) however I don't want to change it again if it's not going to improve???
    (Wahler stat fitted previously)
     
  2. Boris1

    Boris1 Member

    Messages:
    16
    Likes Received:
    4
    Drives:
    Vectra SRI 1.9 CDTI
    If I leave it idling on the drive for a LONG time the needle moves uptowards the 90 but start to drive it and it quickly drops back to the bottom!!
     
  3. 0011728

    0011728 Active Member

    Messages:
    63
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    30
    Drives:
    Insignia Elite Nav Turbo 250PS
    Not uncommon for even genuine stats to be DOA.
    If the car cools when on a fast run with high airflow then its the stat.
    Also - put the display in the car in test mode and see what the temp says on that. (hold down settings button until you hear a beep - and then use the BC button to cycle through the test menus to find coolant)

    The fact that the temperature gauge reading is dependant on road speed would suggest that the thermostat isn't sealing very well in its housing. Even a tiny gap will keep the engine running cool when it is cold outside.

    If you run the engine for a few minutes, the water temperature in the engine should be noticeably above ambient, whilst the hose from the thermostat housing to the radiator should be absolutely stone cold-right up to the T-stat. If it is getting warm prematurely, you need to look at the fitting of the thermostat more closely.

    If the engine is genuinely running cool, you'll get poorer fuel economy and more contamination of the oil with fuel.

    Try re-bleeding the system by idling the engine at operating temperature for a while with the coolant cap off to release any trapped air.

    Also check to see if the cooling fan is running all the time
     
    Last edited: Jan 10, 2017
    voxvect likes this.
  4. Boris1

    Boris1 Member

    Messages:
    16
    Likes Received:
    4
    Drives:
    Vectra SRI 1.9 CDTI
    Thanks for that - the gauge reading was pre stat change .
    After the new stat was fitted and the gauge wasn't moving I then started checking it through the "hidden menu" which was how I found the running temp was only around 68-69 degrees - like you I'm fairly sure it's the stat but I didn't want to go through the whole process again (and the cost) this time I will change it myself.
    Do you know what sockets I need to do it (got a feeling they might be star heads which is why I didn't do it myself last year - got a good metric socket kit but no star heads, if you know what I need I will buy the particular ones)
     
  5. 0011728

    0011728 Active Member

    Messages:
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    Drives:
    Insignia Elite Nav Turbo 250PS
    Found this:

    Note: this is for the 1.9 CDTi 16v engine.

    Take the lid off the expansion tank.

    Remove the battery, this gives better access to everything.

    Remove the hose from the intercooler to the inlet manifold and plug the plastic pipe from the intercooler with rag or paper.

    Remove the Electronic module on the side of the battery box.

    Using water pump pliers, squeeze the clip open on the large hose on the thermostat housing nearest the front of the car and slide along the hose.

    Pull this hose off and dump coolant everywhere.

    Now there is a short hose linking the plastic pipe attached to the side of the thermostat housing which goes to the front of the engine and is bolted on with a torx bolt, this needs removing and the nut holding the pipe to the side of the thermostat housing also needs to be removed, it is a bit akward and is best done with a 10mm ratchet spanner, once the nut is removed, the pipe can be seperated at the front and carefully pulled out back towards the battery then lifted clear and plonked on top of the engine, the one end is still connected to the expansion tank.

    The two medium sized hoses at the back of the thermostat can now be got at with the water pump pliers and the clips should be squeezed open and slid back along the pipes, then these pipes should be pulled off.

    This now leaves the sensor and the small pipe left connected but these are easier to remove once the thermostat bolts have been removed.

    Using a long 13mm socket and long extension bar the topmost bolt can be got at from the battery box, so remove this.

    Next using the long 13mm socket and a short extention bar the lowermost bolt can be removed.

    Now with the housing loose you have to struggle to get it clear due to part of the aircon pipework being hooked over the stud which the platic bracket was attached to earlier with the nut.

    The sensor can now be unclipped, slide the yellow plastic clip away from the sensor and lift the now exposed black clip away from the sensor, this will allow you to pull the connector off.

    You will now be able to access the smallest pipe easily.
    This is held on with a locking clip which is best destroyed with a pair of long nose pliers, just look at the other clips around the car with the paint dabs on them to understand how to release it.
    You will need a small jubilee clip to replace this afterwards.

    You should be able to remove the final hose and with a bit of pulling and twisting, remove the thermostat housing.

    Wipe clean the engine block face and check the rubber seal is sitting properly on the new thermostat housing.

    It is easier to close up the new jubilee clip until it just fits the small pipe before refitting, that way it is less likely to cut into the hose as you are tightening it.

    Refit in reverse order.

    You will need about 2.25 L of coolant to replace what was lost.

    If you drop anything, there is a panel behind the nearside wheel which can be removed with a torx screwdriver, this allows you to get your arm under the gearbox and retrieve sockets, bolts etc.
     
    voxvect likes this.
  6. Boris1

    Boris1 Member

    Messages:
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    Drives:
    Vectra SRI 1.9 CDTI
    That's absolutely fantastic - thank you.
    Guess what I'm doing the weekend (if snow doesn't stop play)
    Once again thanks
     

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