Driving my 99 ML 320 recently in Dallas on a 100 degree day, with lots of stops and starts, the car overheated to a point just below the critical mark and I noticed my brake pedal becoming spongy; had to pump it a bit to secure proper braking. (86K miles on this car)

I got the car home, checked the coolant which was right up there --- checked the vacuum assist hose to the master cylinder (seems AOK)

Does anyone have any ideas in regard to the causes of these symptoms on a hot Dallas day of city driving?

I have not yet physically checked the front brake pads, but don't believe they are critically down ......

Ben Carter

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Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)