Warm Start Rattling Sound for 7 seconds like symptoms of timing chain/tensionner - OM651 Diesel

[youssef9]

Hey guys,

I'm seeking some insights on a peculiar issue with my 2009 w212 equipped with the OM651 diesel engine. During warm engine restarts, particularly after the car has been stationary for around 15 to 50 minutes, I've been noticing a distinct rattling sound. While I'm not certain about the exact cause, the nature of the sound during warm starts gives me the impression that it could potentially be related to the timing chain or chain tensioner. Cold starts have exhibited this symptom only about 3 times.

But normally based on what I know the timing chain/tensionner do this sound only on cold start.

This is a video I made about that:

I'd greatly appreciate your thoughts and experiences on whether timing chain issues could manifest primarily during warm restarts. If anyone has encountered a similar situation or has insights to share, I'd love to hear from you.Thanks for your help.

 

[ajlsl600]

I think thats tensioner and or chain. Tensioner not expensive try it if shuts it up good. If not u need a chain anyway
O rings in tensioner go hard and fail hot oil passes o ring. Tensioner don't work at restart until oil pumped back in and in enough volume/pressure to get tensioner back up to chain block.
Don't let that develop. But do get a 2nd opinion I not stood next to Yr car!!

 

[Bclass2018om651]

Hi ive a 2018 b class Om651 2.1 diesel. Ive owned it 3 to 4 years since i got it from dealer with 7500 miles fsh. I change oil at least twice a year using bulk pack merc correct oil and filter at the minimum so no underserviced. Engine. Its now got 60000 miles. As far back as 15000 miles On clock i now n then (Rarely )had a timing chain rattle only on start up if left unused a while. 2 seconds silence No noise Ive read countless stuff on this subject. I know about revised timing chain tensioners. Etc etc. but what ive noticed over the years is when i do an oil filter change. This then seems to determine how often the next few months. Of rattle. Sometimes nothing sometimes a lot. ? But what i cant understand is this. Why is it when i pull out oil filter. Fast. It appears oil filter housing is dry. Ok i know oil drops into sump when you pull it. But its as if oil drained back into sump good time before. No dripping oil filter.??? So cant see any anti run back valve on filter cap stem. Yes i allways change all seals. But a concern is sometimes when i refit oil filter cap. It seems to screw down easy. Other times. Goes so far then tight last few turns. So removed filter. Inspected seals. All ok. But this time i pull oil filter cap. Pull filter cap stem to centre it lube seals well screw down. Clockwise and back few times. Seats well. This time on next morning start no rattle. Its as if oil filler cap seals at bottom of oil filler cap. Seat better. No run back into sump overnight.

 

[Bclass2018om651]

Ok i cant find any info on some sort of anti run back valve. But when you look at filter stem design. If the bottom seals are intact and seated the oil filter housing. Stem tube is about 2cm above bottom of oil filter base. So if seals are intact. The oil filter housing Should at least stay half to 2 thirds full. Anti run back valve or not. Only way housing could empty dry is if seals at base of stem are faulty or not seating. Food for thought folks.

 

[Bclass2018om651]

B and c seals. B being most important. A is point where oil would fill to in housing. Any more runs back to sump ? So if seals b and c are seated especially B. The oil filter housing should allways be a least half full. If you get me. In my case. Rapid pull of filter. Says housing was empty

 

[Bclass2018om651]

B and c seals. B being most important. A is point where oil would fill to in housing. Any more runs back to sump ? So if seals b and c are seated especially B. The oil filter housing should allways be a least half full. If you get me. In my case. Rapid pull of filter. Says housing was empty

Ok folks im no merc expert. But have had some bonkers answers from so called merc experts on this. Like if its only rattling. For a few seconds in morning. Just ignore it. !! Im thinking. Cold morning cold plastic chain guide. Wack snap. Plastic bits lock chain Chain locks. Pistons say hello to valves. Pistons win. I do realise this is also a combined problem of possible oil leaking chain tensioners. But no 1 delay in oil pressure due to empty filter is a big no no. My experience in diesel engines is static fire pumps. That start and run immediately to full power. So having no delay in oil pressure was a big thing. Infact we fitted pre lube systems To prevent this. Mainly for avoiding turbo damage

 

[ajlsl600]

Big believer in pre lube. I use a USA based kit. Fills accumulator whilst eng running solenoid holds press in tank, releases it next time ignition on.
Also if parked for any Toome at all I crank without allowing start a few times. I agree its another crap design on an motor not in daily use
On my classic I pull the coil lead until pressure on guage then push lead back in. Simlle. Can't go wrong tech. All mb filters, w168 w208 0m651 that I have had have empty filters at first start up and I always change the complete o ring set with filter. Handy enuf for clean dry filter change. Not great in other aspects, will make it out of warranty tho....
I guess one can put a loop and switch thru pump solenoid to a discreet place near diagnostic plug. Don't allow start until oil light out??? Tho at modern oil switch settings it's not the best, today's oil lights work at about the same time as bits start rattling down behind you!!!

 

[Bclass2018om651]

Big believer in pre lube. I use a USA based kit. Fills accumulator whilst eng running solenoid holds press in tank, releases it next time ignition on.
Also if parked for any Toome at all I crank without allowing start a few times. I agree its another crap design on an motor not in daily use
On my classic I pull the coil lead until pressure on guage then push lead back in. Simlle. Can't go wrong tech. All mb filters, w168 w208 0m651 that I have had have empty filters at first start up and I always change the complete o ring set with filter. Handy enuf for clean dry filter change. Not great in other aspects, will make it out of warranty tho....
I guess one can put a loop and switch thru pump solenoid to a discreet place near diagnostic plug. Don't allow start until oil light out??? Tho at modern oil switch settings it's not the best, today's oil lights work at about the same time as bits start rattling down behind you!!!

 

[Bclass2018om651]

On diesel fire pump engines. They start and go straight to max power. So pre lube systems were essential. To protect mostly turbo bearings. Infact we all fitted systems that not only pre lubed but post lubed. After engine shut down. To summarise ive got a 2018 merc. Never used stop start ever. 2 to 3 oil changes a year. Merc oil and filter. I start car every morning. Let idle for 1 min and on shutdown. Idle for 15 seconds. 60000 miles. Timing chain rattle. Utter garbage. These engines must be made of chocolate !!!

 

[ajlsl600]

Om651 built to a fairly mean dudget longivity seems luck of draw. In states the often go over 300,000 miles., inter state trips
I too believe over regular oil changes as best chance of less trouble, however ur case shows this, as not a sure thing.. I am at a little ove 60k miles, it will likely be going in a Yr. For something much old and much simpler to fix with any diagnostic ports, readers, sensors or AI!!!!

 

[Bclass2018om651]

Om651 built to a fairly mean dudget longivity seems luck of draw. In states the often go over 300,000 miles., inter state trips
I too believe over regular oil changes as best chance of less trouble, however ur case shows this, as not a sure thing.. I am at a little ove 60k miles, it will likely be going in a Yr. For something much old and much simpler to fix with any diagnostic ports, readers, sensors or AI!!!!

Hi mate have a look at my recent new member intro post. I just cant accept a cold engine should start with an empty oil filter housing. And discovered a you tube vid about a valve fitted into oil cooler. Housing which oil filter housing directly connects too. Im not sure ive got post in correct section or if me putting link to you tube vid is ok. Can you advise as see you are top member. Thanks

 

[bembo449]

on every derv unit ive heard that rattle its either the chain tensioner or a chain guide is cracked and allowing the chain to move about , on the odd occasion its been a very worn oil pump allowing oil pressure to drop