W108.068 Brake Fluid Reservoir Sensor Cap
 

I just noticed a crack on the rear most cap on the brake fluid reservoir (photo attached). The brakes work fine and there are no leaks. Should I be concerned and is the cap available alone?

Thanks.

It may split all the way at some point. Caps only need to be lightly tightened as the caps are there for splash not pressure.

No idea if they can be gotten separately, Try the sponsor of this site. If nothing turns up, have a look at other Euro cars or those that use Euro parts.

You may look for a used reservoir or cap from one, say from a junkyard. While there is no pressure in the unit, it should be sealed. Brake fluid is hygroscopic and as such will absorb relative humidity if any air is getting in there, which can cause corrosion in the lines, master, and lowering of fluid boil temps.

You may be able to substitute another cap from another brand vehicle.

I found out most brake reservoir caps are 45mm in diameter and use a common thread.

This may help anyone who needs a spare.

I searched Pelican and could not find anything, but a Google search showed a few caps for sale. Sadly none of them were the sensor type.

Toss an ad in the 'Parts Wanted' section. Someone has one of these sitting around.

You do need to change it. It will eventually crack all the way around and there is no tape strong enough to withstand brake fluid.

Not that I have ever tried tape, you understand, but many years ago I had this friend........

Search for part number A000 431 54 33. This is the cap without a sensor.

But it appears this cap interchanges with those on the 116 and 126 so you might be able to pick up one at a wrecking yard.

And this part is not expensive so you might also try the dealer.

If you get into a wrecking yard you need to also check BMW's and Porsche 924's as they appear to use the same one.

Thanks for all the replies. With no leaks, I have to assume the system is still closed. I will keep an eye out for a used sensor cap on eBay.

Hey 124Coupe,

I have an extra cap from a spare reservoir I had bought to fix my floaters. PM me your address and I'll send it to you :)

Jose

Awesome Jose! PM sent :)

And only lightly tighten the cap, the crack is from the plastic getting brittle then the top trying to escape. Inspect the gasket to make sure it is soft.