vacuum leak??

[jb280sl]

I have a recently purchased 1969 280SL. 65,000 miles, automatic trans.
Here is my question: When I first start the car cold, it takes a huge amount of pressure on the brake pedal to stop the car. After it has warmed up after a short drive, brakes seem normal. Another observance is when I am sitting in the car at idle, if I push on the brake the engine races a little.
Any diagnosis or advice???
Jim Bowersox
Annapolis,MD

[jb280sl]

Can anyone help identify this problem. Much pedal pressure required to stop the car when first starting. After driving a little, brakes seem to be normal. Engine races a little when I am sitting at idle when I put pressure on brake pedal. It is a 69 280SL automatic, 65k miles.
Thank you for any insight.
Jim

[ja17]

The racing engine when braking is most likely a faulty brake booster. Also possible for both problems.

[Jonny B]

From what you type this is most likely the brake booster leaking.

There is a lot on the forum about this.
The main search function can really help on this. I am posting this now, but will try a few search links to get you started and amend this item.

Here is one link that I found:
https://www.sl113.org/forums/index.php?topic=24589.msg175770#msg175770

If you use the main search function, just to the right of the "home" button, type in "brake booster" (use the quotes) and also "leak" (without the quotes) and you get two pages of hits, then you can search a bit beyond the link I listed above. The quote marks fill constrain the search to the phrase within the quotes, otherwise you will get pages and pages of stuff, as the search looks for just the words in any order.

[jb280sl]

Thank you very much for the reply. I will start the search.
Jim Bowersox

[Pawel66]

If the brake booster is a faulty/works erratically, be very careful when driving and allow fair distance in front of you to be able to stop the car without brake booster.

[Delvis]

Hi Jim,

i have very similar symptoms on my 1970 280SL and after a couple close calls (freaky brakes) have decided to replace the brake booster, master cylinder and brake fluid reservoir and the check valve as they are tired and need some TLC before i cause a problem on the road. I ordered the parts from Mercedes Benz Classic Centre in Irvine, California. 1-866-622-5277. I simply provided my vin number and Tom at MB Classic Centre confirmed the correct part numbers and provided a quote. all parts arrived today as they were in stock.  i'll be replacing ASAP. if you are a MBCA Member there is a discount on some parts.

i think i have a slow vacuum leak and the booster is failing as the car's brakes would build pressure and eventually work well and the idle stay steed when pressing the brake pedal.

Devlin
Vancouver, Canada