My 560 was doing this, new tank fixed the issue.

Try the cap as they're cheap, but if you have a YELLOW expansion tank... spend $40 to replace it and a few more for a new cap. Stay with OEM parts, the URO brand is hit/miss for the aftermarket.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]