Fiddling with a new EHA isn't a terrible idea, but I would make sure to have two brand new EHA o-rings before taking the old one off. They probably won't want to seal again.

I've had similar issues when one side of my coolant temp sensor died. Easy to check......

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-tp


1990 300SE "Corinne"- 145k daily driver - street modified differential - PARTING OUT OR SELLING SOON - PORTLAND OR. AREA - PM ME FOR DETAILS
1988 560SEL "Gunther"- 190K passes anything except a gas station
1997 S420 - 265k just bought it with a rebuilt trans. Lovely condition