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Discussion Starter #1
Seems to run fine. No really bad noises. No history. Would lose oil pressure over 2500rpm. I pulled the oil pan and found a handful of plastic gravel some of which was clogging the oil pickup screen.

Any ideas how to identify the broken part? How to proceed?
2653712
2653713
 

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1999 ML320, 1998 SL500
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987 Posts
Somewhere there is a detailed thread about the plastic plugs in some oil feed tubes. I don't think that issue applies to you but there are several pictures and a caution that replacing the front oil feed tubes requires removing or somehow damaging the plastic timing chain guides with pieces ending up in the pan.

Just a wild guess but it might be worth pulling the cover to see if those are timing chain guard pieces. Or, maybe a parts house will provide pictures of those items you can refer to.
 

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Equal Opportunity Offender
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
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11,305 Posts
Yes, looks like pieces of a timing chain guide rail.
 

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Outstanding Contributor
R129 500 SL 1991
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1,270 Posts
Almost certainly timing chain top guides.
Loss of oil pressure over 2.5k suggests that there is probably debris in the oil pressure relief valve. I believe getting to this entails removal of oil filter housing.
Guides are mangled because they have been chewed up between cam chain and gears. Chain probably now loose and could jump the gear cogs with potentially serious consequences. Don’t crank the engine. You are right to remove the valve covers.
 

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Discussion Starter #9
It looks like the pieces are mostly intact but missing portions by the chain.

As i inspect them i am not sure what they do? it doesn't seem like they provide much support for the chain. Are they really needed?
 

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Departed 1998 SL500 (and the Pano is in Bogota)
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They are Chain guides. Keeps the chain in place and not to flop around.
 

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1999 ML320, 1998 SL500
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Vague recollection from the oil tube investigation. I think someone said they were oil drains.
 

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Coming soon 1997 SL500
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So is there an improved version of these that are not plastic? Or is the path to simply replace plastic with newer plastic?
 

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Outstanding Contributor
R129 500 SL 1991
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New ones are different type of plastic. More resilient.
 

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Discussion Starter #16
There are holes there so i assume the oil will make its way down.

The space between the cogs is pretty short. It is really hard for me to believe some plastic there will keep the chain from going awry.

It doesn't seem that bad to not install new ones. Can someone convince me otherwise?
 

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Greek God of the R129
SL500-500SEL-190E
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There is a reason why they broke.
Broken guides, plugged oil line to the chain tensioner, etc....
Read post #6 pay attention to what
robm.UK said.
Regards,
aam.
 

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Greek God of the R129
SL500-500SEL-190E
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If you have the oil pan off, look up you will be able to see the lower chain guides, I bet that the
drivers side is half broken/missing.
What viscosity is the oil?
Regards,
aam.
 

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There is nothing in a Benz engine that isn't necessary. Check the cam timing. It is possible some idiot changed the chain without replacing the guides. Possibly your chain is extremely stretched, chewed up the chain guides but has not jumped timing yet. That would be extremely lucky to be that loose and not jump. Check timing. If not good replace the chain and the guides. Not cheap but necessary. If timing is good, chain is good but guides must be replaced before you chew up metal.
 

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1996 SL 500
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There are holes there so i assume the oil will make its way down.

The space between the cogs is pretty short. It is really hard for me to believe some plastic there will keep the chain from going awry.

It doesn't seem that bad to not install new ones. Can someone convince me otherwise?
If the valve cover has gouges from the chain, it has stretched and chewed the guides.
The top guides are two pieces, the big one is the top, the other snaps in from the bottom keeping the chain in place.
The rubber gasket keeps the oil flowing to the right places. Check the cam oilers for missing caps.
With the pan off check the plastic oil pump connector and screen, it keeps debris in the pan and they are hard to find.
Keep a stiff upper lip.
 
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