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Registered
1992 500SEL
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21 Posts
Discussion Starter #1
Greetings ladies and gents on Benzworld

My name is Alex, I'm 24 and I've been a long time lurker on these forums. As a heavy equipment mechanic, I love soaking in other people's knowledge.

I suppose that brings me to the reason I joined, I'm finally seeking the help from those who may have experienced something similar, and I'm surely hoping I just saved myself from a cooked M119.

Background info: 500SEL Build date 8/92 (not sure if it makes it a 92 or 93 model year)
I acquired the car from the second owner with 149k miles and just ticked over 162k miles. I have been tending to the things that a 25 year old Benz needs. Engine harness/TB harness is new, replaced oilers with metal ones, obviously belts, fluids, hoses, suspension bushings etc.

Yesterday serviced transmission and got 2 rear tires put on, car ran great on the way home (used the lift at work), shifted great, idled smoothly and quietly like an M119 should. I double checked the tranny fluid level before I parked her for the night thought all was great.

Started car this morning and heard a loud heavy clack from right bank of engine, popped hood quickly to see if it was the smog pump making some self-detonating noise but I could quickly tell it was coming from the cylinder head. Shut engine off (total run time was 15 sec or less) checked dipstick, oil was good, pulled off oil cap in the off chance I could see something through the hole and low and behold I pulled out a chunk of plastic.

I cannot for the life of me figure out what happened as this piece of plastic bears no relation to any timing components. It literally looks like the leftover ring on a bottle of oil after the seal has been opened. I have yet to pull the oil pan, and as far as I can tell all the plastic timing components are in good enough shape. They will obviously be replaced now that I'm already doing the job, but I've researched multiple threads and looked over parts diagrams as well as pictures of the new timing plastic and the chunk I removed looked totally alien. Timing plastic is chocolate brown whereas this plastic is jet black and still very flexible.

Any advice would be greatly appreciated, , it's my second car so I'm in no rush for transportation, but I want to save this engine from being turned into a coffee table :crying
 

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Registered
1999 S500; W140.051
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772 Posts
Did the engine idle/run poorly in the 15 sec interval?

Was the loud noise repeating?

You could try taking all plugs out; turn engine by hand and check for any interference.

If no interference, then you would probably have to remove cyl head cvrs & check valve timing.

If there is interference, then you already know what that means.
 

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Registered
1992 500SEL
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21 Posts
Discussion Starter #3
Hi daidnik,

Thanks for your reply, the noise wasn't metallic sounding like a bad lifter, but I did pull the plugs to verify no damage from a faulty plug. I did shine a light down the hole to see if there was any damage to the tops of the piston and all looked well from the limited view (no borescope). I was hoping it was a piece from a bad oil filter, but the filter and housing were all as they should.

During the time the engine was running it idled smoothly and showed no signs of choking or hesitation, which is why I initially though it was smog pump related. The engine has never had a startup rattle or noisy lifters, just the typical noisy clutch engagement for the smog pump.

Appreciate any and all thoughts, Im working on uploading pictures will load asap
 

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Registered
1995 S600
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564 Posts
Hey Sneezy, welcome. From my experieces with the M119 I would not be surprised if that was a piece of the chain tensioner. Where the oil fill cap is located is also the same proximity of a few select piece that 'could' show themselves there I would think.
While you still yanked a chunk, the engine could still run nicely...it's when the chain starts slapping and more pieces start to come apart and fill up the intake screen that the problems seem to start.
At this point I would suggest pulling the valve cover, get in there with a good light and examine the guides. I researched the hell out of this before diving in, M119 is a GREAT engine but the guides for the timing chain was in my opinion a weak design that wears well before the engine itself even will.
Again, at this point it's time to get in there and look.

Chris
 

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Registered
1992 500SEL
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21 Posts
Discussion Starter #8
Thanks for the reply Chris,

Yeah the circle piece of plastic definitely has me stumped. Havent had the filler cap off since last oil change (great engine doesn't burn or drip a drop of oil), and to me it looks like part of a oil bottle cap seal. However I always use a funnel since I'm mess prone, so I know part of the cap seal couldn't go down the funnel.

Gravity goes down last I checked so I don't know from where in the top end it appeared from, unless getting caught in chain and being flung from oil pan to top.
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,929 Posts
I deed, it does look like the seal ring from a quart of oil. Possible that the PO, or some tech, left it behind.
 

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Registered
1982 MB 380SE 1999 S500
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371 Posts
I would say it is a left over piece of an oil bottle cap. No piece of the chain guides is like that. The difficult investigation is that it looks to be complete with no damage. If it went through the timing chain it would be crushed. If it went under a cam lobe it would be flattened. That's the only moving parts under the valve cover.

You may have another problem. Pull the valve cover to see, Not difficult. Just nine valve cover screws and 8 spark coil retainer screws. All 5mm hex. Lower rear valve cover screw is in a tight space.

Pull all spark pulls and rotate crank clockwise only to test for any binding/interference

Lets us know what you find..
 

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Registered
1999 S500; W140.051
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772 Posts
Make sure to do two complete revolutions at the crank.

Unfortunately, you cannot check valve timing without removing cyl head covers.

If you decide to do that, you must be very careful & gentle with those aged wires.
 

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1992 500SEL
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21 Posts
Discussion Starter #12
Thanks for all the replies gents!

I did immediately pull the valve covers once I heard the noise to check for collateral damage. Cam lobes and tops of lifters are all in good shape, but I dipped my finger in the leftover oil in the head and there were some fine chunks of plastic. While the covers are off I'm going to replace the guides (which I should have done while doing oilers).

I do know the head covers have to come off for timing inspection and guide replacement, my memory escapes me though if the cams have to be pulled first. Will have look closer and dig into it a little more. Not worried about the upper wiring harness or throttle body harness as they are new, but thanks again for the heads up! In the mean time I will drain the oil through a coffee filter and pull the lower pan and report back with my findings.

Thanks again for all the help!
 

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Registered
1999 S500; W140.051
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772 Posts
Be very careful removing the two guides on the top. The little fingers break off very easy and you can't let those pieces go down into the timing gear area. They can cause chain to jump on gear.

They are almost certain to break when you try to unclip the one on top remove them so be prepared.
 

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1982 MB 380SE 1999 S500
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371 Posts
The cam timing is viewed easily now that the covers are off. Rotate the crankshaft clockwise until the left inlet cam sensor is line up with the L shape bracket on the inlet cam sprocket. Have 4 6mm screws from the valve cover handy. You should see a hole on the left exhaust cam sprocket side that will line up with the timing hole on the cam bearing block. Insert the 6mm screw into the cam bearing block into the hole on the sprocket. All of the other three pin locations on the cam sprockets should line up. If not note how far from each hole is a mismatch and post it here. .
 

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Registered
1992 500SEL
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21 Posts
Discussion Starter #15
Update:

I was able to pin all 4 cams at what appeared to be around 42 degrees. I saw he 'L' attachments on the intake cam but I wasn't able to pin it while it was lined up with the cam sensor. I may have misunderstood though, but it looked like it lined up with the backside of the bolt that holds the cam sprocket to the cam.

Pulled a few pore chunks or plastic out of the timing cover from what I can access, this plastic appears timing related as its brown plastic. My oil catch was full so i have to dispose of that before I can drain the oil/pull pan, but I'm already expecting chunky.

Thanks daidnik for the heads up! I was smart enough to replace those plastic chain guides up top when I did the oilers, just not smart enough to do the other chain guides. But I will exercise the same caution as before, thanks!
 

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1982 MB 380SE 1999 S500
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371 Posts
Great job. All four pins in at around 45 degrees. Hence, no interference problems.

How tight is the chain? Which side are you getting the plastic pieces from? They should not be going side to side. Look with a strong light into the spaces under the cam sprockets for any broken pieces. The noise you heard may of been due to the breakup of a chain guide. You may have to remove the chain tensioner and check for any broken pieces of the chain tension-er plastic guide.

Replacing the chain guides is minor surgery.
 

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Registered
1992 500SEL
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21 Posts
Discussion Starter #19
Got a chance to drain the oil, but didn't have enough time to pull the pan today. My coffee filter strainer didn't work as well as I hoped beings that the oil was so thick since I couldn't warm it up. Although what I was able to strain were all very fine chunks. All smaller than grains of sand so I'm chopping the larger chunks were just up top or are resting nicely at the bottom of the pan. Should have time tomorrow to pull the pan, I had more running around today than expected.

However the chain did feel nice and tight, I probably did about 5 full crank rotations watching the chains on the sprockets closely to make sure nothing jumped. I've got the upper guides on order from the local dealer, but as far as the timing cover goes is it a one piece or two piece affair? If memory serves me well I recall reading about possible head gasket leaks from removing timing cover. That's my biggest worry about getting at the chain tensioner. Would like to pull the upper guides, but I'll have to re-read some old threads on if it can be done while all assembled and not having to re-time everything.

Thanks again for all the help, this forum is the best!
 

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1982 MB 380SE 1999 S500
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371 Posts
To gain access to the chain guides I pulled the cam shafts on the side I was working on. I left pinned the side not worked on. I also used a wood wedge stuck between chain on sprocket and opening in the head to keep chain on sprocket. Upper guides held in with 2 pins each on front face of head so everything mounted on front of head must be removed. There are some very good explanations how how to time listed on the forum. If the chain tensioner guide is bad then crank damper has to be pulled to gain access to mounting pin.

Your getting into some serious work. Go slow. I found my guides were cracked at the lower pin and broken off.

When you pull tensioner make sure you have a new gasket. Do not used the old one.

Good time now to do a compression check and leak-down test before further work.

Removing the valve covers should not effect the cylinder head gasket on a M119 engine.

Its a lot of work to change a $10.00 part.

Marking the chain location on all four sprockets helps in putting it back together.

Even though the timing is set a 45 degrees on the crank the right exhaust cam shaft will move when the chain is relaxed due to valve spring pressure on the cam. About one tooth rotation.
 
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