My brakes work but the pedel goes all the way down to the floor until I pump them up then they are good for a while. Fluid level is fine. Also car sometimes pulls to the left when braking. This "spongy brake pedel" only happens only once in a while. Front brake caliper. Master cylinder, Brake booster? Where do I start?

Master cylinder. Pretty easy fix and a good time to replace the brake fluid as well.

Pulling to the left could be a number of things, as simple as air pressure to front end issues.

Pumping the pedal up sounds like a bad master cylinder. As for the spongy brake feel, if the fix to the other problem doesn't get this I'd go around and bleed all four corners to ensure no air in the system.

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Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

Thanks guy's I saw a master cylinder rebuild kit on ebay for $10. Any experience with rebuild kits or should I go with a new "rebuilt" unit?

Before you buy rebuild kit or rebuilt master cylinder, Try flushing the brake fluid completly out of systen with new clean fluid. This would also get any air out of system and save you a lot of money and time if that's all it needed.

I would go with rebuilt master cylinder myself.

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'10 Chrysler T&C Stow-N-Go White. Grandpa's ride.

'13 Chrysler 200 Touring Candy Red. Grandma's ride.

Age and cunning will always over come youth and vigor.

I had the same problem at one time. The pedal felt really soft and the pedal play was crazy. I decided to bleed the brakes and use new brake fluid. I have no problems since then and brakes work BEAUTIFULLY.

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Audi TT

The day I had that problem was the day I realized the brake fluid resevoir had a front and rear chamber.

I was fine once I filled both chambers and cleaned things up enough to actually see the front chamber.

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Greg Schwall

1983 300SD - 465,000 miles

I've actually done something just like the previous posts. I had a leaky caliper or two and they let all the fluid out. So when I went to stop the pedal would go practically to the floor, I looked at the reservoir and it looked nearly full. Hmm... eventually I noticed the two grommets on the reservoir so I figured maybe it has two chambers, it did. Soon afterwards I found /fixed the caliper leaks by rebuilding them.

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Jeff M.
Mercedes W123 DIY pages are now located here.
1983 / 1984 300D Sold
2000 CLK430 Cabriolet ~58k Sold
2005 Avalanche 4x4 ~66k

A little more inspection and found out that my front passanger side caliper is locked up. The outside piston is locked open and the inside locked shut. I removed it and tried to lose the outside piston with a large C-clamp and it will not budge. Alot of rust around the piston. I hope that this was the problem.

That would cause the pulling but if your pedal goes to the floor wouldn't the master cylinder do that?

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200