Mercedes-Benz Forum banner

My V8 may have died

1K views 17 replies 6 participants last post by  Wessman 
#1 ·
Hi

I was about to take my lady for a ride with my old and faithful s500L. I heard an ugly noise from the engine room and I decided not to start it anymore. So, when we were walking instead of driving I started guessing the source of that sound. After opening the valve covers I saw pieces of plastic and then I knew my guess was the right one.
To the point; to see the total damage, I decided to open the timing cover but I realised that I don't know how.
So here is a picture below and I need someone to tell me, how to proceed. The engine is M119.

Sincerely. Marco from Finland
 

Attachments

See less See more
1
#3 ·
Don't turn over motor with starter

Turn the motor over by hand at the crank for 2 full revolutions to check for any interference. If interference is found, then heads will likely have to come off if motor was started or run in that state.

Next step is then to check valve timing. If motor was not run with interference of pistons & valves, then noise may have just been plastic pieces (likely from upper chain guides seen at top of cyl head) going down thru timing chain/gear train. Others have said that this makes a nasty sound.

If motor does not have valve/piston interference, you are lucky and you only have to replace upper chain guides; check/set valve timing and clean out plastic bits in sump pan.
 
#4 ·
My idea is to see and inspect all the chain guides ja maybe to replace the chain if everything else (like the valves) is ok. How do I get the cover open? Now everything is removed between the radiator and the chain cover. Even the pulley that is still on that picture of my first message.
 
#5 ·
In the 124 forum you will find links to the FSM. Go to the DIY sticky and you'll see the links. The FSM has all you need to know for removing the chain cover. However, I would wait on pulling it until you've determined what has happened. The M119 motor has a double row chain that seldom let's go. Take the easy road first.

Jayare

Sent from my XT1080 using Tapatalk
 
#6 ·
Do that manual turnover interference check FIRST before anything else.

It's incredibly easy as you've already got the plugs out, etc.

Put wrench with socket to the crank and do the 2 full revolutions test.

If something clunks and stops your turning THEN you know you must dig deeper into the motor.

If nothing clunks and you successfully complete the interference test, THEN you can proceed with check of valve timing which is also easy with those cyl head covers off.

Only then will it be appropriate to continue with replacement of chain guide parts.

You may not have to open the timing case, but you probably will have to remove the sump pan.
 
#7 ·
Odometer says 188 000 miles and I believe the chain is misplaced. My plan is to open the chain cover and check the situation. I check the chain and install some new guides and rotate the engine. After measuring compression I will put in a new chain. If everything is OK, of course. If not, I will take the cylinder heads off.

Thanks for the tip of the w124 forum but it did´t contain this info.
 

Attachments

#9 ·
I looked inside every cylinder with an endoscope and there are tiny scratches on pistons number 3 and 7. Nothing major, I hope. When I rotate the crankshaft, the camshafts do not move so I need to open the front cover and I still don´t know how.
 
#12 ·
Lift up on the chain on both sprockets. Is it loose?
If you can move the crank and the camshaft sprockets do not move the timing chain has broken. Piston/valve interference would destroy valves, piston crowns, bend rods, etc. You should not be able to complete two revs of crank because of interference .
 
#13 ·
The M119, like other Mercedes engines, is an interference motor. The likelihood that a bunch of valves are bent is very, very, very high. Not to mention damage to the Piston tops.

Honestly, the path of least financial resistance is going to be getting a second hand motor and installing it.

Good luck

Jayare

Sent from my XT1080 using Tapatalk
 
#17 ·
A very tough procedure.

Makes winding a new chain in a piece of cake in comparison.

If chain really IS broken, then I would think it would be slack on the outside of one of the heads. Probably the left head (driver's) side. You should be able to pull the chain upwards.

If this really is the case, then pulling the motor is probably going to be the best option.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top