Hello folks thanks for accepting me as member. I want to re open the discussions on om651 cold start chain rattle. I have a b class 2018 b200 sport 2.1. Got it 4 years ago from merc 7500 miles. Im an ex mechanic not merc specific knowledgeable. I have without fail changed oil and filter using merc oil and filter. 3 times a year. Im now at 60000 miles. And getting chain rattle on every cold overnight first start. 3 secs then silence. Infact i first heard chain rattle at 10000 miles but was extremely rare. Strange thing is it started after my first diy oil change. ( yes i change all filter o rings ). Ok so now yes i prob need new chain or at least try change hydraulic chain tensioner. But my worry is this i think rattle will return. And this is why !! Over the years i have noticed when pulling oil filter out. Even fast theres no sign of oil in housing. As if oil drained back to engine. Ok i know it does when you pull oil filter stem But you would think filter would be still dripping. My car never rattles rest of day after first cold start. So i tried this. Stopped hot engine and removed filter rapid. Yes oil drops back into sump but filter is wet and dripping from secs before being submerged. I put filter back in empty of oil housing. Start hot engine. Guess what. Chain rattle for 3 secs hot engine. Presumably till filter housing refills. So im thinking if oil housing is emptying into sump overnite. This is what. Initially causes damage to oil fed tensioners. No oil in them. Chain bounces them them they lose all oil keeping Due to tensioner internal seal damage ? Then. Slack chain starts. Exacerbates chain stretch with grab n pull on slack chain. Ok guys long post but does anybody get me on this theory. And any ideas on why filter housing emptys overnight. I did see a post on you tube search ( om651 oil cooler check valve leak ). Where a guy removes a plastic stem that has a spring loaded check valve on the end of it. Anybody know if this check valve is what keeps oil in filter housing. Theres no way a filter should empty overnite. Oil feed should have no delay. Waiting on filter filling. I think this issue is not only important for timing chain issues but also ensuring longevity of full engine other cars with different type canister filters. Filters fitted inverted mostly have an anti run back valve. Designed into filter.
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