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Old 07-24-2020, 01:06 PM
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Diseasel300 Diseasel300 is offline
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Posts: 6,071
Quote:
Originally Posted by roky View Post
yeah, its not that it wasn't opening, or was stuck open, its that one is twice the gap at 100c
Don't forget, the thermostat serves TWO purposes on these engines. One is to allow cool coolant in from the radiator, the other is to BLOCK the coolant bypass port. If the thermostat isn't opening correctly, it isn't blocking the coolant bypass port either. The result is a low intake of cool water from the radiator and excessive re-circulation of hot coolant from the block.

I went through this with the SL last year. Original 1983 stat was lazy and wanted to run 100C all the time. Bought a new stat from the dealer and threw it in. Worked for ONE DAY, then overheating again. I went through everything thinking that an OE stat couldn't possibly be bad that quick. Finally replaced it with a Wahler and tested both in boiling water. Wahler was wide open, OE replacement couldn't even slip a fingernail in the gap. Overheating solved.

Never assume that "New = Good" I learned that lesson.
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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]
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