Thermostat

[Mattz]

hi everyone. Had the water pump replaced with the belts as well but the garage didn't do the thermostat as I wasn't aware about changing this at the time. The car instantly started having a temp fluctuation after this work. Only very small ones but it was always rock solid before. Is this something to worry about ?

 

[Mnbrennan]

It's likely to be air in the system

 

[Mattz]

It's likely to be air in the system

Ah yes ! Should I take it back ?

 

[FRANKIE]

Ah yes ! Should I take it back ?

Some thermostats have a small hole drilled in them to allow air to pass through. You might want to wait a day or so to see if it steadies out. I think @t-tony might be able to give better advice......................Frankie

PS. Since he's in Florida at this moment, he's probably out eating din-din right now. Give him a few hours to get on line.

 

[Mattz]

Some thermostats have a small hole drilled in them to allow air to pass through. You might want to wait a day or so to see if it steadies out. I think @t-tony might be able to give better advice......................Frankie

PS. Since he's in Florida at this moment, he's probably out eating din-din right now. Give him a few hours to get on line.

It's been like it for a while now. The work was a few months ago.

 

[FRANKIE]

It's been like it for a while now. The work was a few months ago.

Any time I get some work done on a car and something else goes wrong immediately, I always feel as if they must be related. They almost always are but the bi*** of it is that on a few occasions, fixing the first problem might exacerbate another problem thats just starting. I have yet to change the thermostate in my Z3 so I don't know what's involved. In transverse engines, they can be nasty work as they are sometimes burried, however in rear wheel drive engines they are usually located right up front and are usually much easier to get to. There will be someone along soon who has done the job and can advise you better that I. I don't know what your capabilities are but this is usually something most people can take care of themselves.................Frankie

 

[Dino D]

It's not a big job nor expensive parts but when it fails it's very inconvenient and at worst can cause overheating (as many of us know first hand... )
Just get it changed along with the thermostat housing and then bled properly.

 

[FRANKIE]

It's not a big job nor expensive parts but when it fails it's very inconvenient and at worst can cause overheating (as many of us know first hand... )
Just get it changed along with the thermostat housing and then bled properly.

Are you saying that the housing has to be replaced along with the thermostat in a Z3?...............Frankie

 

[Dino D]

Are you saying that the housing has to be replaced along with the thermostat in a Z3?...............Frankie

Yes they can crack, ask how I know...
They are plastic. I was going to get a metal one but they not readily available but to be fair the original did last 15+yrs so I just got an original one from the dealer.

 

[t-tony]

Some thermostats have a small hole drilled in them to allow air to pass through. You might want to wait a day or so to see if it steadies out. I think @t-tony might be able to give better advice......................Frankie

PS. Since he's in Florida at this moment, he's probably out eating din-din right now. Give him a few hours to get on line.

Also some t/stats don't, I would drill a 3mm (1/8") hole in it making sure not to damage the main body of the stat. It allows better bleeding.

Tony.

 

[Mnbrennan]

I would have thought that if the thermostat was at fault, then the symptoms would be showing before the water pump change. Having said that, it's always worth swapping them over as they are cheap to buy.

If I were you I'd take it back, describe the symptoms and explain that you suspect there is still air in the system.

When I did my M52 recently the gauge was fluctuating until all of the air was out. And yes, I also suffered a broken thermostat housing when I swapped it over!

 

[duckhunt]

I've just done a cooling overhaul.

I ordered a 'circoli' tstat housing from ecp, to my suprise it was metal. Good stuff.

If you want to try bleeding out the air first yourself, there are many different methods shown online, but what I did -

If possible raise the front of the car up.

Check your Coolant level is on or just above cold line.

Unscrew bleed screw (not all the way out)

You may want to put a rag around the tank (careful of the fan position) and drip pan under the car.

Run engine with heater on max

Look for bubbly Coolant coming from bleed

Keep running until engine gets up to temp( this should activate tstat)

You can give it some revs gently to 2.5k

Stop when you have no more bubbling from bleed screw, just a steady stream.

Reinstall bleed screw (careful of over tightening)

Rinse any spilt Coolant with water from engine bay.

Top up to cold line when cooled.


It'd be a fairly simple half hour tops, to get any air out. Wouldn't trust the garage if they couldn't do it right the first time.
There should be no fluctuations, I just did all this work and the needle gets up and stays dead centre all the time.
Some may disagree with this method, there are so many, this is what I've done before, and my neighbor who's worked at bmw for 20 years confirmed this method. And it's worked. Cheers

 

[Dino D]

I've just done a cooling overhaul.

I ordered a 'circoli' tstat housing from ecp, to my suprise it was metal. Good stuff.

If you want to try bleeding out the air first yourself, there are many different methods shown online, but what I did -

If possible raise the front of the car up.

Check your Coolant level is on or just above cold line.

Unscrew bleed screw (not all the way out)

You may want to put a rag around the tank (careful of the fan position) and drip pan under the car.

Run engine with heater on max

Look for bubbly Coolant coming from bleed

Keep running until engine gets up to temp( this should activate tstat)

You can give it some revs gently to 2.5k

Stop when you have no more bubbling from bleed screw, just a steady stream.

Reinstall bleed screw (careful of over tightening)

Rinse any spilt Coolant with water from engine bay.

Top up to cold line when cooled.


It'd be a fairly simple half hour tops, to get any air out. Wouldn't trust the garage if they couldn't do it right the first time.
There should be no fluctuations, I just did all this work and the needle gets up and stays dead centre all the time.
Some may disagree with this method, there are so many, this is what I've done before, and my neighbor who's worked at bmw for 20 years confirmed this method. And it's worked. Cheers

I've used this method and I'm no mechanic!
My local garage does say these are 'b@tch' to bleed but always gets it right.

Nice one on the metal thermostat. I could only find US suppliers. I take it it was a good casting ad flush fit?

 

[duckhunt]

I've used this method and I'm no mechanic!
My local garage does say these are 'b@tch' to bleed but always gets it right.

Nice one on the metal thermostat. I could only find US suppliers. I take it it was a good casting ad flush fit?

Yea seemed decent, no leaks, came with gasket (not tstat gasket) although I had ordered one from dealer anyway.
Neighbor seemed impressed with it as he has seen the plastic ones go, although the old one I removed seemed sound enough. I believe it was the only option from euro Car parts anyway

Although out of everything the actual thermostat was the only part I got from dealers, ridiculously expensive but just wanted peace of mind.
Other parts were
Pulleys - INA (oem I think)
Fan clutch - Sachs
Belts - contitech
Wpump - hepu (had metal impeller)

 

[Cooper]

Hmmm. In my ignorance I got it right, lucky me???. After I drained the coolant into a bucket from the raised front end I changed the tstat and the water pump. I then poured most of the coolant back in [I didn't want to change it all as it was done by the previous owner], ran the car for 2 mins, dropped the car level, filled her up and ran, topped up with a bit of extra coolant. Everything works nicely with no bleeding required.