Brake fluid in booster

[P'bert]

Beginning a couple of months ago, I've been needing to add brake fluid to the reservoir of our '85 300D. Today, I removed the vacuum line to the booster and found that there are a couple of inches of brake fluid in the bottom of the booster, so I ordered a new master cylinder and O ring. From reading posts on this forum and Haynes, it appears that replacing the master cylinder is not difficult. When I do so, I will remove all of the brake fluid that I can from the booster. However, I'm wondering if the brake fluid may cause eventual damage to the booster. Any thoughts? At present, the brakes work perfectly, except for the leak.

Phil

'85 300D, California style
'84 300D, Euro style

[pawoSD]

If there was that much in it I would think it has begun destruction of the booster....I think factory spec is that there cannot be more than 30cc's of fluid in the booster or it will be damaged. There's warnings all over the factory manual stuff about fluid getting in there.....

[boneheaddoctor]

Originally Posted by P'bert

Beginning a couple of months ago, I've been needing to add brake fluid to the reservoir of our '85 300D. Today, I removed the vacuum line to the booster and found that there are a couple of inches of brake fluid in the bottom of the booster, so I ordered a new master cylinder and O ring. From reading posts on this forum and Haynes, it appears that replacing the master cylinder is not difficult. When I do so, I will remove all of the brake fluid that I can from the booster. However, I'm wondering if the brake fluid may cause eventual damage to the booster. Any thoughts? At present, the brakes work perfectly, except for the leak.

Phil

'85 300D, California style
'84 300D, Euro style

Been posted before....your brakes will get progressively harder as your vacuum capacity diminishes as it filles up with fluid. Besides the master cylinder is on its way out.........I have heard brake fluid can damage the booster....I replaced mine on the W116 as a precaution since I got a good price for a remanufactured one....but will it really damage it? Not sure. If you can get a remanufactured one for around $100 i'd do it..if you have to spring for $200+ I would wait for it to fail first.

[Matt L]

I'm with BHD. If the booster completely fails, you will still have brakes with increased pedal effort. Really the worst that can happen if it fails while driving is loss of vacuum for other systems.

[JimmyL]

Originally Posted by Col.Klink

Brake fluid will definitely damage the booster diaphragm ;you can use good ol hot soapy water to neutralize the fluid at this point but it takes a lot of air to blow out the thing ,then squirt a little spray silicone in it .

You will need to suction the fluid out, then poor something in as recommended above, then suction out again.

[dannym]

Originally Posted by JimmyL

You will need to suction the fluid out, then poor something in as recommended above, then suction out again.

A mity-vac would work here.