[Three_thirty_I]

Hi guys,

So as the title states, I need to replace the thermostat on my 330i. I have NO errors or anything as such to prove that the thermostat is faulty, but the engine operating temperatures are way colder than they should be no matter how the car is driven or outside temperature, and this has been the case for quite some time. I did replace both temperature sensors some time back to rule out a possible fault with one of them, but problem persists, and to the extent that in winter the climate control does not really warm up the cabin as it should.

Anyway, since I only want to replace the thermostat, I would prefer to do this without having to fiddle too much with the electric water pump. I would have to replace the three aluminium bolts if I remove the water pump, but my concern is also that they apparently don't like sitting with no coolant and can end up seizing up.

Now my car being a manual, I can remove the electric fan to gain extra working space since it is extremely tight from what I can see when working from below, with the thermostat hidden mostly by the water pump. So my question is, can the thermostat be removed without having to remove the water pump? I know that getting those hoses off is a PITA and typically the screw heads for the pipe clamps are almost impossible to get to (will have to invest in one of those "bendy" screwdriver things).

So if anyone has done this or also only had to replace their car's thermostat, some tips would be most appreciated. I am going to lift the car and take a proper look again to see what sort of space there is. I have seen a few DIY vids on Youtube (the one with the dude and his Gorilla friend, and then a 335i), and this just highlights the PITA that this is, but in both cases both the thermostat and water pump needed replacement.

I appreciate any help here!

[Efthreeoh]

Look up Eninty's DIY to remove the water pump. He covers removal of each part separately. The t-stat bolts to the water pump and comes out first, so you can remove it without fiddling with the WP. The bolts can be reused as the are screwing in the aluminum-bodied WP. The fan does not need to be removed to get the T-stat out.

[Three_thirty_I]

Originally Posted by Efthreeoh

Look up Eninty's DIY to remove the water pump. He covers removal of each part separately. The t-stat bolts to the water pump and comes out first, so you can remove it without fiddling with the WP. The bolts can be reused as the are screwing in the aluminum-bodied WP. The fan does not need to be removed to get the T-stat out.

Thanks, actually did find his thread, and also JamesUKE92's thread which includes lots of handy photos! I will take a read through the doc and reference the pics to see how he Eninty got the thermostat replaced without removing the water pump. Yep, the water pump bolts are the aluminium ones, I reckon if they are not too expensive I will probably just buy them so that if I am forced to remove the pump I have fresh bolts. The two holding the thermostat onto the water pump as you say are normal reusable bolts.

I am still just very much at a loss that I have no errors or engine light, and this "suspected" problem has existed for quite a while now. Most of the time the operating temperature in the hidden menu sits around the low 80 degrees Celsius range, it is suppose to be around 105 degrees Celsius and only drop to lower temperatures depending on how you are driving. Even mapped or high output temperature modes are higher than what I am seeing. I do hear the cooling fan come on very early on after the engine has been driven from cold start. I am also still somewhat confused about how this thermostat works, in that my understanding is that the ECU controls it, yet it is then not doing as it is told, or for some reason it IS being told to act the way it is. And then the lack of an error code or engine light if it is faulty. With that said, I also have what I suspect to be a dodgy MAF sensor which I have on order, so this could also play a part. In the meantime, the car gets a weekly drive to keep things going until I get these issues sorted out. This has proven to be the most stubborn car I have ever owned!

Will update in due course!