[Mr. Toad]

In virtually every other car I've owned, the coolant reservoir (like the brake fluid reservoir) is translucent so that the fluid level can be viewed at a glance. Any idea why BMW uses solid black plastic, which requires that you open the cap and check the float, and makes it impossible to determine the level when the engine is hot?

[bennye90]

The same reason why the e9x gasoline series has no oil dipstick

[PichaDis11]

Because BMW started to look for ways to cut costs and have us stranded on the side of the road. The correct level for E9x is when the lower ball is level with the rim of the tank.

They're back to making them white now though.

[Mr. Toad]

Originally Posted by PichaDis11

Because BMW started to look for ways to cut costs and have us stranded on the side of the road.

They're back to making them white now though.

Your theory wouldn't surprise me, but is black plastic that much cheaper than translucent/white?

When did they ditch the black reservoirs?

[PichaDis11]

Originally Posted by Mr. Toad

Your theory wouldn't surprise me, but is black plastic that much cheaper than translucent/white?

When did they ditch the black reservoirs?

To that I actually do not know. Just going from experience I've just seen where the E9x just cracks easily in weirdest places. Not sure if a design flaw or material weakness.

[Thorin]

Cracking plastic is not unique to BMW. It's a material weakness (the environment under the hood is extremely harsh, and you have to mix in the chemical compounds of whatever the tank is holding).

[shadow191]

The coolant reservoir isn't just an overflow like most cars. It's actually pressurized so potentially the black plastic is easier to make in the thickness and shape needed. On most cars, you could swap a plastic water bottle and it would still function. You can't do that on the BMW.

[John 070]

Originally Posted by shadow191

The coolant reservoir isn't just an overflow like most cars. It's actually pressurized so potentially the black plastic is easier to make in the thickness and shape needed. On most cars, you could swap a plastic water bottle and it would still function. You can't do that on the BMW.

I was waiting for this answer....it's 100% ftw

Some cars it's nothing more than a cap that snaps in place, and coolant actually evaporates over time....

[sea6speed]

Originally Posted by bennye90

The same reason why the e9x gasoline series has no oil dipstick

Not sure how the color of the reservoir would reduce emissions...

[Mr. Toad]

Originally Posted by shadow191

The coolant reservoir isn't just an overflow like most cars. It's actually pressurized so potentially the black plastic is easier to make in the thickness and shape needed. On most cars, you could swap a plastic water bottle and it would still function. You can't do that on the BMW.

This is a very good point, which hadn't occurred to me. However, I'm still not sure I understand why it has to be black; surely color isn't the characteristic that allows it to be pressurized, right?

[Rivers]

I always figured it to be an aesthetic look seeing how there is other clear/white piece that is not covered.

[delmarco]

White translucent plastic containers always look dirty and discolored over time.

Also once you go Black you ain't going back!

LOL!

[The Nightman]

Originally Posted by shadow191

The coolant reservoir isn't just an overflow like most cars. It's actually pressurized so potentially the black plastic is easier to make in the thickness and shape needed. On most cars, you could swap a plastic water bottle and it would still function. You can't do that on the BMW.

Other makes have pressurized reservoirs that are clear:



Black was either cheaper or it was chosen for appearances since it won't look stained overtime like some clear reservoirs.

[shadow191]

I was just throwing out it was a different design and that's potentially why it's black. It may very well just be cost or aesthetics. I personally prefer it as it's more discrete.

[CTinline-six]

Likely aesthetics.

[Mr. Toad]

Originally Posted by freedomfries

Other makes have pressurized reservoirs that are clear:



Black was either cheaper or it was chosen for appearances since it won't look stained overtime like some clear reservoirs.

We're talking about a part that's under the hood; personally, I'd put more weight on the functionality of at-a-glance level checks than any aesthetic concerns.

BTW, do you know what kind of car this is in the pic?

[Welcome to NBA Jam]

Because black expansion tanks matter.

[Efthreeoh]

The color of the plastic has to do a lot with what type of plastic is being used and the shape of the part being produced, which dictates the type of plastic used for the part. In the example pictured, the part is a small sphere, which structurally can take more pressure than a square tank (which the E90 tank basically is). Translucent plastics are generally polystyrene based and weaker than a typical ABS type of plastic.

The E90 tank is quite large and cube shaped for packaging under the hood. The sphere tank pictured is small and looks to be injection molded in halves then friction welded together. The sphere shape allows for that less expensive part production using a high-density polyethylene plastic. The BMW tank is a complex shape and is probably roto-molded and sonic welded for final assembly.

[EB89]

Black looks better and you can just open it to look at the level.

They probably didnt design it for when the third owner wants to DIY it and complain about this stuff.

[Delta0311]

Because BMW is trying to be more multicultural, you racist bastard.

But no in my 2016 228 the coolenat reservoir is white. It's black in my 11 e92 and it was also black in my 07 e90.

[Thorin]

If you really want black and reliable, look for a machined bulb...

[Wksk]

Originally Posted by Mr. Toad

We're talking about a part that's under the hood; personally, I'd put more weight on the functionality of at-a-glance level checks than any aesthetic concerns.

BTW, do you know what kind of car this is in the pic?

Looks like a VW. My girls gti has the same looking tank.