Some have a gasket, some have an o-ring, do not use the o-ring on the gasket type nor the gasket on the o-ring type!

You will have to pull it to check....

No sealant in either case, please.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!