Location of 1953 Buick regular brake fluid filler cap

L Hop

New member
Can someone tell me more exactly where this is? The manual says there is an access hole cover under the floor mat on the left side (Really? A 66-year-old floor mat still alive? Mine has carpet, firmly attached and tucked under the top and side panels) that accesses the filler cap nut. In order to reach it, I am going to have to cut out a small piece of carpet and replace it after filling with brake fluid, and would would sure like a ballpark location before I start slicing away. Thanks, LHop
I have one with the OE rotten rubber mat. Yes, many of these old cars accessed the master cylinder in this manner. You may be able to remove the door sill plates and lift the carpet to gain access to the master cylinder access hole.

L Hop

New member
Thanks. It's a little bit more difficult than that. The guy who installed the carpet about 10 years ago used a carpet adhesive. Plus, the cardboard (that's all it really is) panels at the side and back are so fragile that if I try to get the tucked carpet out from under, I'm sure they will crack badly. I guess that will be my last resort, but I'm hoping someone has filled the reservoir before and knows more precisely where it is. I guess I can raise the car to see the reservoir from below - I'm not very mobile to crawl under. I like 99% of the '53's design. This is the 1% that makes no sense to me, considering that 60% of the engine compartment is vacant.
The service info you describe sounds like it was taken from a '54 or '55 shop manual. The '53 manual refers back to the '52 edition for the manual brake system.

Attached is a sketch from the '52 shop manual. It shows the master cylinder mounted on the left frame rail well forward of the brake pedal and toe board. Access would have to be from under the hood.

A photo from the '51 shop manual attached shows the filling tool for the master cylinder in use under the hood.

The Master Parts Book shows a part number for a master cylinder access cover only for the '54-55 models. My guess is you won't need to disturb the carpet.