New member. Om651 b class 2018. Timing chain rattle. Ideas on the real reason this happens.

[Bclass2018om651]

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.

 

[Wighty]

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.

Maybe you are just overthinking it because you are a mechanic ? 60k miles on a car with stop start maybe it’s just due a new chain and you are overly sensitive to engine sounds ?

 

[Bclass2018om651]

Thanks for reply wighty 60 k miles. 3 oil servs a year. Stop start dash display programmed to off (individual). Since 2nd day i owned car. Yes like i said it prob does need chain or tensioner. But with what ive said above no way should it be DUE one. my oil filter drains back to sump every night. FACT ive proved it ! And i think its not just my om651 engine. I really do think this is the route cause of many chain and tensioner failures. Well whatever is going wrong with oil filter run back overnite. This is what starts the ball rolling

 

[Bclass2018om651]

Thanks for reply wighty 60 k miles. 3 oil servs a year. Stop start dash display programmed to off (individual). Since 2nd day i owned car. Yes like i said it prob does need chain or tensioner. But with what ive said above no way should it be DUE one. my oil filter drains back to sump every night. FACT ive proved it ! And i think its not just my om651 engine. I really do think this is the route cause of many chain and tensioner failures. Well whatever is going wrong with oil filter run back overnite. This is what starts the ball rollin

Thanks for reply wighty 60 k miles. 3 oil servs a year. Stop start dash display programmed to off (individual). Since 2nd day i owned car. Yes like i said it prob does need chain or tensioner. But with what ive said above no way should it be DUE one. my oil filter drains back to sump every night. FACT ive proved it ! And i think its not just my om651 engine. I really do think this is the route cause of many chain and tensioner failures. Well whatever is going wrong with oil filter run back overnite. This is what starts the ball rolling

hi wighty. Ive been experimenting more with my theory on oil filter drain. So i tried this. Got another old oil filter cap. Removed the stem from the cap. And placed stem in oil housing. Without cap. So blocking drain dump to sump plug. Filled housing with oil. Left overnite. Oil housing drained to sump. Via outside feed port. So next i filled housing with oil. Disconnected Stem in filter in. Screwed oil cap on. Cold engine start. No timing chain rattle. !! So now im thinking it must be the plastic cap valve In attached you tube video. Some people say its a oil cooler thermostat But its basically just a plastic rod with spring loaded bullet shaped plug on end Looks more like a one way valve its directly in the flow tube to filter housing. If you look at pics of oil cooler housing rear.

 

[Wighty]

Sounds good buddy , but it’s all above my pay grade

 

[ajlsl600]

I hav also noted that. But it was same on w208 v 6! I also change all o rings, one other thing. I NEVER TRY TO ACCELERATE, REV CAR UNTIL ITS BEEN RUNNING FOR A MIN. also when I rtnd from 3 months away I always crank motor 3, 4 times before I allow it to catch
And yes its odd that chain rattle often starts after an oil change. Again I think op prob right on his theory. Now I think about it my g230, s were the same drop oil in evening hide key, change filter in am, near alway, near dry.???? Never ever had chain rattle on them tho.

 

[Steve@Avantgarde]

Its a short single-plex chain attached to the high pressure fuel pump. I would just think that its just a poor design or rather a single-plex chain cant cope with the high compression torque demand of a diesel engine.

That said, I see 651 engines every day, only a handful i see have chain stretch in relative comparison, so perhaps you are just unlucky. Otherwise we would be fitting chains to every single 651 that exists, and the reality is, we dont.

 

[Bclass2018om651]

Its a short single-plex chain attached to the high pressure fuel pump. I would just think that its just a poor design or rather a single-plex chain cant cope with the high compression torque demand of a diesel engine.

That said, I see 651 engines every day, only a handful i see have chain stretch in relative comparison, so perhaps you are just unlucky. Otherwise we would be fitting chains to every single 651 that exists, and the reality is, we dont.

 

[Bclass2018om651]

I have no idea how many 651 have timing chain rattle. But forums and sites are awash with similar cold start rattles. Not just 651. What im offering up is my theory on why this is happening. Infact for me its no longer just a theory. Ive proved it by various tests. FACT. My oil filter housing drains dry down unfiltered supply side overnite. So if anybody is reading this. With similar cold rattle. Dont take my word for it. Remove your oil filter. Before next morning cold start. If its bone dry. Not a drip. As if housing drained many hours before. You got oil run back. This isnt rocket science its basic engine mechanics. Try it !!

 

[star]

We change a lot of 651 and 654 chains, 651 mainly for rattle on start up, new chain and tensioner fixes the problem without touching the filter check valve. How did you check that the oil is draining back?

 

[ajlsl600]

I guess if one checks the filter in am and it's near dry the oil has ran back to the sump? I have noticed this on all my benz w168 w208 and 166. Often wondered why as I always change the o rings. I think? There is a check valve on the interior side of the filter housing?
Theory must be there is enough oil sitting on around ends, and mains for this not to be a prob.
On tensioner, it's well known that at shutdown oil leaks past o rings and therefore tensioner has to refill upon start to function properly
In my case and on w166 I think I will prioritise a tensioner change over Xmas to mitigate the possibility of rattle.
On thar subject is it easy to get at or, as w168 a real pig.

 

[Bclass2018om651]

We change a lot of 651 and 654 chains, 651 mainly for rattle on start up, new chain and tensioner fixes the problem without touching the filter check valve. How did you check that the oil is draining back?

Yes i do understand a new tensioner / chain will fix the problem on a lot of cases. High miles poor maint engines yes. But if its a dry filter drainback. Then every cold start. You have oil pressure delay. This also dont help tensioner and sends it on its way. Then chain slack. Snatch grab stretch. I checked drain back by removing filter. Before cold start. Total bone dry. Not a sign of secs before being immersed in oil. So next test i removed stem from oil filter cap. Placed in housing. Filter in. Filled with oil. No cap on left over nite. Oil gone. Down unfiltered supply side. So i filled up filter. Again carefully filtted cap over stem. Cold engine start. Silence liquid chocolate. Next removed filter cap. Refitted another cap with joined stem. Filter. Obv cant fill housing. Cold start. Rattle . Next. Hot engine. Mines only ever rattles cold start 3 secs. Remove filter. Drains to sump. Fit filter. Hot engine rattle. Ok im not saying this is every chain scenario fail. But hey. How many times you heard the. Story. Only rattles on morn cold start a few secs. Not only on om651. But other mercs. Somebody take this serious. Its not rocket science.

 

[star]

I think the valve shown is the oil pressure relief valve and to hold oil in the filter, it needs the sealed oil filter cap on it causing a small vacume to hold oil up. This will not stop oil from draining from the oil pump pick up tube.

 

[MinionBob]

I have no idea how many 651 have timing chain rattle. But forums and sites are awash with similar cold start rattles.

That is the problem. Forums are a tiny sample of ownership and people do not come on to a forum to say 'hey...my car is working great..!' Forums are a biased and unrepresentative sample.

 

[ajlsl600]

I think the valve shown is the oil pressure relief valve and to hold oil in the filter, it needs the sealed oil filter cap on it causing a small vacume to hold oil up. This will not stop oil from draining from the oil pump pick up tube.

Also if o rings on tensioner are good it will hold the internal oil (not much) mitigating any refill delay, that must be the design factor, as such I don't see a prob, tho I personally think a premature tensioner change can only be a good thing, still like to know how much drama to change that, tho I will get one over Xmas period

 

[MinionBob]

, still like to know how much drama to change that, tho I will get one over Xmas period

Easy - Did mine a while ago so cant remember 100%, but basically a bolt-out, bolt-in job; remove a few pipes/clips/brackets but not a biggie as access is good from the top

 

[ajlsl600]

Easy - Did mine a while ago so cant remember 100%, but basically a bolt-out, bolt-in job; remove a few pipes/clips/brackets but not a biggie as access is good from the top

Grand ta for info. On w168 was down back behind eng, tight for space to unwind n get out aggrivated by some git in factory using 4ft pipe to tighten it!!!

 

[Bclass2018om651]

I think the valve shown is the oil pressure relief valve and to hold oil in the filter, it needs the sealed oil filter cap on it causing a small vacume to hold oil up. This will not stop oil from draining from the oil pump pick up t

Also if o rings on tensioner are good it will hold the internal oil (not much) mitigating any refill delay, that must be the design factor, as such I don't see a prob, tho I personally think a premature tensioner change can only be a good thing, still like to know how much drama to change that, tho I will get one over Xmas period

Hi star and aj600. I meant to post other day i worked out valve on cooler manifold is not. Anti run back valve. As i said. Its a oil cooler bypass / thermostat. Aj600. My filter drains dry overnight cap on or off. But i did think the vacuum hold thing you said. So drainback isnt a valve in cooler. Does the oil pump have a ant run back valve or maybe valve somewhere else. ?? But anyhow i this morning actually cured my cold rattle. With my first version of my basic idea. And its worked !!!!

 

[Bclass2018om651]

Hi star and aj600. I meant to post other day i worked out valve on cooler manifold is not. Anti run back valve. As i said. Its a oil cooler bypass / thermostat. Aj600. My filter drains dry overnight cap on or off. But i did think the vacuum hold thing you said. So drainback isnt a valve in cooler. Does the oil pump have a ant run back valve or maybe valve somewhere else. ?? But anyhow i this morning actually cured my cold rattle. With my first version of my basic idea. And its worked !!!! Off for a coffee. Clues in the pic lol

 

[Wighty]

Hi star and aj600. I meant to post other day i worked out valve on cooler manifold is not. Anti run back valve. As i said. Its an oil cooler bypass / thermostat. Aj600. My filter drains dry overnight cap on or off. But i did think the vacuum hold thing you said. So drainback isnt a valve in cooler. Does the oil pump have an ant run back valve or maybe valve somewhere else. ?? But anyhow i this morning actually cured my cold rattle. With my first version of my basic idea. And its worked !!!!

Good job buddy .
If you ever change cars your username isn’t going to work