Z4-forum.com

Sorry for double posting but it was kind-of hidden in my other thread....

Basically the coolant pump is on its way out so gonna get replaced very soon but do I need to do the thermostat at the same time?

Also having looked up the part number and keyed it into ebay found a couple at different prices:

http://www.ebay.co.uk/itm/THERMOSTAT-WI ... Swl8NVYbGl

Or should I spend the extra for this:

http://www.ebay.co.uk/itm/BMW-E90-E91-E ... SwtUtXA8Ya

Both claimed to be OEM spec don't recognise the brand on the branded one and both look the same from the pictures any advice appreciated.

Cheers

Behr and Mahle are both respected names and OEM manufacturers. I would fit parts from either without worry.

I can't see any benefit in doing the thermostat as a "while you're in there" job - not really. A benefit could be simple peace of mind. If there's a stored fault code in the diagnostics for the 'stat or its leaking then that's a different matter.

Thermostat is not needed to replace when replacing your waterpump. Besides that: replacing a thermostat is a 15 minute job so you can always do it when it's failing afterwards

Cheers guys will just do the pump then

Yeah, you don't need to do it but I know most do at the same time. Maybe if you're paying then it makes sense? Or is it worth saving a bit of hassle bleeding the system etc.?

I read somewhere that if the pump fails and you get to an overheat situation the thermostat can be affected by that, so maybe it depends how bad your pump has become!

I had the 'stat changed on mine when the pump was replaced - mine did get hot enough for the red light so given that both parts were 9 years old I couldn't see much benefit in changing the pump and not the 'stat, especially as I have no facility for DIY repairs.

Maybe your circumstances for DIY fixing also have a bearing?

Change 'em both then you have piece of mind

Can you reuse the fixing bolts for the thermostat?

Or are they single use like the fixing bolts for the pump.

saj77 wrote: ↑Tue May 12, 2020 7:02 pm Can you reuse the fixing bolts for the thermostat?

Or are they single use like the fixing bolts for the pump.

To answer my own question and for information - you re use the two thermostat fixing bolts as they are standard bolts not single use aluminium like the water pump ones.

Just fitted my pump and stat today

saj77 wrote: ↑Thu May 14, 2020 3:04 pm To answer my own question and for information - you re use the two thermostat fixing bolts as they are standard bolts not single use aluminium like the water pump ones.

Good info. Thanks for posting. How hard did you find the DIY?

I didn’t do it myself in the end

I found a mechanic friend who did it at my house - still with social distancing.

It seemed straight forward to him - it took him about 30 minutes to fit the parts once the coolant was bled and car on axle stands.

He ran the electronic bleeding procedure twice topping up coolant as needed - that took 25 minutes!

And then he cleared the thermostat fault using his snap on diagnostic tool.

All for £70

Had to top it up after 2 miles once thermostat opened I guess. Got light on dash.

Topped it up. Maybe 500ml. Drove 20 odd miles. Spot on. Heating red hot, so no air in system