How to change the thermostat on an E46 325i
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    How to change the thermostat on an E46 325i

    First of all i had a problem with my car not heating up and reaching optimal temperature. the needle on the instrument cluster for the water temperature was only just making it above the blue section on the readout. no matter what i did i could not get the car to reach the 12 o'clock position or half way as some may be more familiar with that term.. So after a couple of phone calls i decided the thermostat was to blame for the car not heating up correctly. So i ordered a new one and set to work on the old girl.

    First of all i got my car in the air on a set of ramps as i wanted to save he antifreeze i had just put in (6 a litre) so i needed to be under the car for this reason. you may not need to do this if you are using new fluid and don't want to drain it off like i did. I removed the under engine plastic plate. it has 3 screw at the rear, 2 down each side and 3 push fit grommets at the front. then i undid the drain plug. but remember if you go down this route you must hold the adjustment screw bolt firm and make sure it doesn't turn when releasing the drain screw or you risk breaking off the lugs on the bolt and the bolt becomes obsolete. same goes for when you tighten the drain plug back up on refitting.

    so with that sorted and the bonnet open i started by removing the full air box assembly.
    picture with air box in place, ps second picture has a glove over the airpipe as i didn't want any crap getting in there.

    removed, i had to take out the 3 push fit gromets on the front and then i had to remove the 2 10 mm screws holding the air box to the strut front section. undo the air pipe and disconect the air floe meter plug and then it will just lift out.

    next step was to remove the cooland pipes. all you do is lift the hose clips upwards and then wrestle them out. there is a large one at the radiator top and a smaller one at the bottle. the other end to the thermostat is a large one and so is the other pipe at the other side of the thermostat.

    so with these pipes disconnected i had to now make space to get in and remove the thermostat. you can not do it with the viscous fan and shroud in place.
    first off get your self a 32mm open end spanner. put it on the fan nut

    then get some very good packing at put it over the righthand side engine componants as you don't want to break any thing when you do the next step.
    with the spanner now sticking up, give it a good sharp whack with a rubber mallet clock wise. it moves quite easily actually

    then unscrew the fan until it comes off. at this point you will need to remove the shroud to anable the fan to come out and give you the room to work. it has on mine a torx scre in the left hand side and a push fit grommet on the right hand side as you look at the car. remove these 2 items.

    then remove the plug on the top left hand side and the plug just under it and move out of the way.

    the fan and assembly can now be lifted care fully away.

    you should now be able to see the thermostat.

    remove the plug

    and now you are ready to undo the 4 bolts holding it in place. there is a fifth one you need to slacken off also just so you have a bit of leaverage to remove it when all the bolts are out. it is responsible for a bracket that holds the bottom left bolt.
    remove the 4 bolts, the bottom 2 are 10mm, the top left is 10mm and the bottom right is 13mm. then slacken the bolt above the thermostat hold the bracket, 11mm. and you should be able to then wiggle the thermostat away.

    and removed

    i cleaned up the area and put some clear sealant around the part to aid the re sealing. there thermostat cost me 40 from eurocar parts,(was half price)

    re fitting is the opposite of removal with attention to the water pipes on mine were a little stiff on the connectors and needed a bit of extra persuasion . when you are ready, fill the car and bleed as per dealer instructions.

    just wanted to show you my airbox, it was shattered in alight accident and as i am tight and did not want to spend 45 on a second hand one i plastic welded it with my soldering iron. i used about 12 pieces to get it to this stage. lol

    thanks for looking and i hope this will help some of you out one day.
    Last edited by vauxfan; 17-10-2013 at 15:53.

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    E36 TDS (17-10-2013),lancsbreaker (28-01-2016),PAYNO (17-10-2013)

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