Finally its over. No more screechy noises.
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Hi all. I have just done an oil change, flushed the coolant and refilled and now the engine keeps on revving itself up and down. Can it be due to a bit too much oil?
Yea it happened to me and the cap stopped it immediately best 10£ fix lol
I changed the cap a few weeks ago 
More likely you need to bleed the coolant of air a bit more. Could be upsetting the coolant temperature sensor and sending confusing signals to the ECU. Make sure when you top up the coolant that you have the heater in the max heat position to avoid air locks. Regards to oil just check the dipstick level.
I bled the coolant for 30 mins with hear in full power. There were no bubbles. However, i have very mild heating from the blower, also i noticed that the level in the coolant reserve tank does not change, it looks like there is no flow to or from the reserve tank at all
any expansion of the fluid might be getting absorbed by the air that sounds like it’s still in the heater. Try slowly squeezing the coolant tubes to massage any air out ? wear gloves obviously.
How long is the bleeding process supposed to take upon completely flushing the coolant?
Generally takes me less than 10 minutes on any car I’ve done. The important thing is to fill it up slowly.,less chance of trapping air. If the heat from the heater is only mild you can be certain that air is trapped in it. Sometimes slightly revving the engine for a couple of seconds at a time can force the air out. Another tip is to leave the radiator cap off until the main hose starts to feel warm/hot then put it on again.
I don’t think there should be much coolant flow to the expansion tank really unless the engine has overheated or the radiator cap has failed. Anything else should be handled by the radiator fan coming on at just over the correct operating temperature. I generall y leave the radiator cap off until I can feel hot water being directed to the radiator ie just a the thermostat starts to open. You should see a fair number of bubbles coming out as you look in at where the radiator cap screws on.
The expansion tank only had water in it prior to flushing. After i flushed by opening the tap bottom of the bumper i filled in with a pinky colour coolant all the way to the top, left coolant cap open, turned the heating up to full heat, maxed out the blower and let it run for 30 mins. The temp reached 90, the fan turned on a few times and maintained the temperature all with the cap off. Still the heating was veeeeery mild. Closed the cap, drove for over 100 miles and the expansion tank still only has water, no pink coolant, not heat also no overheating either
As i said i didn’t expect much to go into the expansion tank. You clearly have an air lock in the heater matrix. Why are you putting the blower fan on ? There is no point.
Personally i would refill the system again but do it very slowly and massage the hoses. Works for me every time
I just refilled, ran the engine without the cap for nearly 40 mins, there were no more bubbles but the revving up and down still continues and still no heater any ideas?
Crikey ,without the radiator cap on for that long you should have had hot water running into and potentially over flowing the expantion tank, as did mine a week ago when I failed to twist the cap on fully. I’m struggling to think of what to check next.
Just read that the coolant system takes 8 litres (if including the heating and coolant reserve)
Just had a quick look at the service book. Each bank of the engine has a drain plug. If you want to properly drain it and properly fill it up you will need to follow the procedure below . I’d probably replace the thermostat after you’ve drained the system whilst your at it as the service book gives this as one cause of not enough heat from heater.
Oh wow. In that case i definitely did not flush the system properly as it only took about 4 litres of coolant after flushing. I thought you only need to release from bottom radiator drain plug.
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There are 2or 3 temperature sensors on the thermostat body. Might be worth checking they are connected properly. part number 6 in particular
and finally the coolant concentration needs to be between 30 and 60% so aim for 50% concentration of the correct coolant and you’ll be fine.