Coolant Expansion Tank And Coolant Recommendations

[EViS]

The coolant expansion tank float stick on my 2004 manual 2.5l e85 has snapped off. I've managed to retrieve it from the tank but it probably means the tank is in need of replacing now as a pre-emptive measure.

Autodoc lists lots of tanks (Febi, Meyle, Mahle, Hella, etc.) but which one is OEM? Or should I be buying this from BMW direct?

Whilst replacing the tank and coolant, anything else which I should swap out (thermostat, level sensor, o-rings, etc.)?

Could I also please have a recommendation for quality coolant?

 

[enuff_zed]

Hi, I use Febi Bilstein coolant which meets all the requirements.

When I swapped the expansion tank on wifey's I bought Hella, purely because it came with a new sender unit in the bottom.
If yours is a manual then that should be all you need, though you could consider new o-rings for the hose fittings as they can flatten over time and not reseal properly.
If it's an automatic then there is an oil cooler thermostat which the expansion tank fits over the top of. This will in all likelihood disintegrate as you remove the tank, so have a new one to hand.

 

[WouterZZZZ]

“ If it's an automatic then there is an oil cooler thermostat which the expansion tank fits over the top of. This will in all likelihood disintegrate as you remove the tank, so have a new one to hand”: YES, very good recommendation, it happened to me recently. It just fell apart after having removed the tank carefully.

 

[enuff_zed]

“ If it's an automatic then there is an oil cooler thermostat which the expansion tank fits over the top of. This will in all likelihood disintegrate as you remove the tank, so have a new one to hand”: YES, very good recommendation, it happened to me recently. It just fell apart after having removed the tank carefully.

Mine was more sneaky than that. Obviously the plastic casing weakens over time and there's a big old spring inside. Mine waited until I'd removed the tank and half turned away, then it fired the casing at my head!

 

[patriot66]

The coolant expansion tank float stick on my manual 2004 e85 has snapped off. I've managed to retrieve it from the tank but it probably means the tank is in need of replacing now as a pre-emptive measure.

Autodoc lists lots of tanks (Febi, Meyle, Mahle, Hella, etc.) but which one is OEM? Or should I be buying this from BMW direct?

Whilst replacing the tank and coolant, anything else which I should swap out (thermostat, level sensor, o-rings, etc.)?

Could I also please have a recommendation for quality coolant?

My original from factory Behr '03 expansion tank split back in '17 and I replaced it with a Meyle HD item with a 2 yr warranty. Dissapointingly this split just last month, so only got 5 years out of it. Replaced that with a Febi Bilstein item that seems excellent quality...fingers crossed.
Any Glysantin G48 type coolant should be fine. I can recommend Comma G48 Xstream (meets BMW GS94000 requirements) https://www.commaoil.com/passenger-vehicles/products/view/563/XSG5L/ No issues and no signs of any corrosion over the 7+ years I have used it in my Z4
You could replace the radiator (just done mine), thermostat and waterpump as they WILL all fail sooner or later on a 18-20 year old car. I've replaced all mine over the years along with appropriate o-rings and sensors. The only coolant system items that seem to fair well are the actual hoses

 

[EViS]

Thanks for the reply all. Coincidence or not, I drove 3 miles this morning and the temp gauge went to max red and beeped. I immediately pulled over and let the engine cool down a tad. I checked the coolant level and it seemed fine. Regardless I turned around and went straight back home. On the way home the temp gauge did not move past the middle. Weird and a hell of a coincidence this!

Could this also indicate a faulty thermostat or water pump which I should probably replace whilst changing the tank? Anything else I should be looking at or anyway I can test these before replacing?

 

[EViS]

An additional question - with the engine running and the water tank cap off, should there be a visible flow of coolant back into the tank at the top? As there is no flow from what I can see.

 

[enuff_zed]

An additional question - with the engine running and the water tank cap off, should there be a visible flow of coolant back into the tank at the top? As there is no flow from what I can see.

Should be able to see a thin stream of water coming into the top of the tank from the right, as you look from the front.
If you get a new tank with a new sender unit in the bottom this will eradicate any possibility of a level sensing issue.
Regarding the pump and thermostat, do you have any idea how old they are? It could be prudent to spend the extra and change them too while you have the system opened up.
Not sure the pump would cause a transient fault like that. Possibly the thermostat could if it stuck, or the sensor on it is playing up.
Was the cooling fan running? If it stopped for any reason then that could cause a spike in temperature.
From the front of the car, look at the top left (drivers side) of the fan. There's a big connector there. Look closely at the thin green wire for signs of damage.
Tbh, I think if it were me and the components looked fairly old, I'd change the lot to be on the safe side.
While you're in there, check the drive belts for condition too.

Whereabouts are you? Is this all stuff you're happy to tackle yourself? Maybe someone close by with previous experience.

 

[EViS]

An additional question - with the engine running and the water tank cap off, should there be a visible flow of coolant back into the tank at the top? As there is no flow from what I can see.

Should be able to see a thin stream of water coming into the top of the tank from the right, as you look from the front.
If you get a new tank with a new sender unit in the bottom this will eradicate any possibility of a level sensing issue.
Regarding the pump and thermostat, do you have any idea how old they are? It could be prudent to spend the extra and change them too while you have the system opened up.
Not sure the pump would cause a transient fault like that. Possibly the thermostat could if it stuck, or the sensor on it is playing up.
Was the cooling fan running? If it stopped for any reason then that could cause a spike in temperature.
From the front of the car, look at the top left (drivers side) of the fan. There's a big connector there. Look closely at the thin green wire for signs of damage.
Tbh, I think if it were me and the components looked fairly old, I'd change the lot to be on the safe side.
While you're in there, check the drive belts for condition too.

Whereabouts are you? Is this all stuff you're happy to tackle yourself? Maybe someone close by with previous experience.

Definitely no stream of water coming in. Assuming the M54 and N52 have the same setup with a return stream (or do ALL engines, incl. non-BMW have a return stream)?

No idea on the age of the pump and thermostat, could very well be original. However, as the pump is not electronically controlled (as is the case on the N52), it's hopefully not the root cause. But I won't fully discount it.

I *think* the cooling fan was running at the initial stop. However, when I got home I checked that the radiator was cold, fan was running and the top pipe was very hot. Not sure how this may help with diagnosis?

I changed the belts, starter and alternator at the beginning of the year as the starter had died and I guessed that the alternator had only so much life left. I should be ok doing the work myself, I just need some pointers and a couple YT videos to follow .

 

[enuff_zed]

Radiator cold?
As in no water going through it? Thermostat?
All pretty easy jobs tbh.
Look twice and act once, to be sure. :wink:
Lift the fan out for access and then it's a pretty simple job to swap the thermostat. Get a new temp sensor at the same time while you're in there.
But the lack of a return stream of water to the tank is a bit odd. That would suggest the pump is not circulating it.
Not quite sure of the cooling system flow pattern as to what affects what though.

 

[EViS]

Radiator cold?
As in no water going through it? Thermostat?
All pretty easy jobs tbh.
Look twice and act once, to be sure. :wink:
Lift the fan out for access and then it's a pretty simple job to swap the thermostat. Get a new temp sensor at the same time while you're in there.
But the lack of a return stream of water to the tank is a bit odd. That would suggest the pump is not circulating it.
Not quite sure of the cooling system flow pattern as to what affects what though.

I'll wait for everything to cool down and have another good look, but I didn't see any return coolant coming back into the tank...

What manufacturer of thermostat is recommended / who makes BMW's? Is it Wahler or Behr by any chance? Much of a difference between them?

 

[enuff_zed]

Radiator cold?
As in no water going through it? Thermostat?
All pretty easy jobs tbh.
Look twice and act once, to be sure. :wink:
Lift the fan out for access and then it's a pretty simple job to swap the thermostat. Get a new temp sensor at the same time while you're in there.
But the lack of a return stream of water to the tank is a bit odd. That would suggest the pump is not circulating it.
Not quite sure of the cooling system flow pattern as to what affects what though.

I'll wait for everything to cool down and have another good look, but I didn't see any return coolant coming back into the tank...

What manufacturer of thermostat is recommended / who makes BMW's? Is it Wahler or Behr by any chance? Much of a difference between them?

I fitted a Febi Bilstein 3 years ago and it's going fine so far.

 

[EViS]

Radiator cold?
As in no water going through it? Thermostat?
All pretty easy jobs tbh.
Look twice and act once, to be sure. :wink:
Lift the fan out for access and then it's a pretty simple job to swap the thermostat. Get a new temp sensor at the same time while you're in there.
But the lack of a return stream of water to the tank is a bit odd. That would suggest the pump is not circulating it.
Not quite sure of the cooling system flow pattern as to what affects what though.

I'll wait for everything to cool down and have another good look, but I didn't see any return coolant coming back into the tank...

What manufacturer of thermostat is recommended / who makes BMW's? Is it Wahler or Behr by any chance? Much of a difference between them?

I fitted a Febi Bilstein 3 years ago and it's going fine so far.

Do you remember whether it came with a gasket or not? There is a separate part number for the gasket but would seem odd (to me) for a new one not to come with the new thermostat housing?

 

[enuff_zed]

Do you remember whether it came with a gasket or not? There is a separate part number for the gasket but would seem odd (to me) for a new one not to come with the new thermostat housing?

It was this one:
https://www.amazon.co.uk/febi-bilstein-43624-Thermostat-casing/dp/B00PNLHGL2/ref=sr_1_1?crid=1NRL41KWXE952&keywords=febi+bilstein+43624&qid=1658153174&sprefix=febi+bilstein+43624%2Caps%2C65&sr=8-1

 

[patriot66]

I'll wait for everything to cool down and have another good look, but I didn't see any return coolant coming back into the tank...

What manufacturer of thermostat is recommended / who makes BMW's? Is it Wahler or Behr by any chance? Much of a difference between them?

I fitted a Febi Bilstein 3 years ago and it's going fine so far.

Do you remember whether it came with a gasket or not? There is a separate part number for the gasket but would seem odd (to me) for a new one not to come with the new thermostat housing?

Wahler Thermostats are OEM for M54 I fitted one back in November '18 and Meyle HD waterpump with metal impeller. Gaskets included. Both still going strong.

 

[EViS]

Great stuff. Thank you both for all of the recommendations and advice. I've ordered a new thermostat, expansion tank and coolant. Hopefully I can still get everything installed this week.

Seeing as there may very well be an air lock in the system as well. What's the best way to clear this (once I've installed the above), especially one that may be quite big? I've read many methods from merely undoing the bleed screw next to the tank to parking the car on a hill and revving it with the cap off?

 

[enuff_zed]

M54, I usually simply have the front end up on ramps (also find it hurts my back less not having to lean over so far). Then fill it up slowly with the bleed screw out until it bubbles out. Let it settle and repeat until it stops going down. I also give the hoses a bit of a squeeze to help things along.
Did the old Project Freeleeta thermostat only last week and filled up by that method. Gave it two 28 mile twisty B-road blasts to work and back today in 38 degree heat and the temp gauge never moved from its normal position of halfway.

 

[EViS]

Once I've removed the thermostat and tank, any chance there could still be a bigger air blockage further up stream which might then need some more force to shift upon refilling with new coolant?

 

[enuff_zed]

Once I've removed the thermostat and tank, any chance there could still be a bigger air blockage further up stream which might then need some more force to shift upon refilling with new coolant?

Never encountered one myself tbh. Maybe others have?

 

[patriot66]

M54, I usually simply have the front end up on ramps (also find it hurts my back less not having to lean over so far). Then fill it up slowly with the bleed screw out until it bubbles out. Let it settle and repeat until it stops going down. I also give the hoses a bit of a squeeze to help things along.
Did the old Project Freeleeta thermostat only last week and filled up by that method. Gave it two 28 mile twisty B-road blasts to work and back and the temp gauge never moved from its normal position of halfway.

Agree with all of what enuff_zed says above^^^, 100% DEFINITELY get the front up on ramps (or axle stands) as the radiator/expansion tank are then at an exaggerated highest point for bleeding. You can also get a bucket underneath so you don't waste any coolant. Leave the undertray off until you've been on a road test and checked levels after. And ramps DO also make it much easier on the old back !