krazzdav

If the mark on the pulley is off, u can use the keyway to make a new TDC mark on the pulley and realign the chain but I would recommend having the pulley replaced ASAP if that's the case so u don't cause damage to ur engine. Worse case scenario is the pulley finished separating and flies around you're engine compartment and the crank and bearings gets damaged from it being out out of balance.

jpman

Agreed. I will go with the replacement route. Basically have him pull of the pulley and check mark, if its off then replace pulley and verify pulley and top position of piston and then get cam timing. I believe that will be the procedure tomorrow.

VVF

Does your car sound like this by any chance?
https://mbworld.org/forums/c-class-w...ml#post6089361

jpman

Nothing like that...

Mine sounds like its about to start and you can here the compression of the pistons. As a matter of fact at one point when it stops cranking you can hear what sounds like an air pop coming from the intake.

ncmudbug

Have you done a compression test?

jpman

No compression test yet. The car does not seem to be in timing so I'm not sure if that will yield accurate results. The mechanic called me to tell me he was removing the crank pulley to verify if it has moved. Best case scenario it has moved and we can replace it and then get timing back. Then I will check for compressin test. Not sure if this would be the correct order?

ncmudbug

That's my point. If you're not getting any compression, something is mistimed. Of course, if your wrench can determine that the crank pulley is off, that might get the same info.

I'm speaking from ignorance here but in my experience with other motors, the crank pulley goes on only one way. But, like I say, I don't have any knowledge of how the M271 pulley is attached to the crank.

jpman

Just confirmed, the crank pulley moved. I will post pics later tonight. Right now I have a question. The seal on the crank is not leaking oil. Should I replace it or apply the if it ain't broke don't fix it. Another question, the bolt holding the crank, the 27mm bolt, do I have to replace that too? Is it a stretch bolt?

RWDlifer

A backfire/air pop from the intake is not a good thing....it almost always indicates effed up timing, fingers crossed there's no metal on metal contact....

jpman

got it. Yeah the car was not in timing because of the pulley marks. I have confirmed the pulley outer ring shifted, moving the marks in te wrong location. Don't know if I should replace the crankshaft seal, or leave it without touching it. It currently does not leak oil. Does the bolt holding the pulley need to be replaced?

krazzdav

One of the docs I gave u had the directions but replace the seal. The old seal is worn to the old balancer and plus you already have it apart. Changing a $300 balancer and not the $5 seal doesn't make sense.

The manual didn't say anything about replacing the bolt that I recall.

At least u know it was the balancer that spun and can get it sorted easily now.

ncmudbug

That's great news (I think)!

How is the graduated part attached to the pulley? Is there a harmonic balancer? Is that what is marked? It seems a little odd that the thing that tells the world where TDC is would be something that could slip but I'm sure there is a good reason. I thought the sprag bearing on the alternator pulley was a dumb idea (when it blew and took out my A/C compressor), but it is actually a very good idea.

jpman

So here she is... The mean to all of my timing chain DIY problems



Got the new pulley and will be installing tomorrow. We basically got the top guide from the crank and lined it up to the mark on the timing casing that is used for the pulley for reference and locked the cams to line up with their respective marks. From there they cranked it by hand and made sure all the marks continue with their alignment marks and made sure its all in timing. Tomorrow should be mounting the new damper and starting her up. Hopeful everything goes as planned tomorrow.

VVF

Nice!

What I don't understand is how did it spin like that?
Have him check all the other pulleys and check the alternator overrun pulley. There must have been a reason for this...

jpman

Well the alternator itself got replaced about two years ago, one day I started getting the shop notification on the car and we had to replace it. Other than that, the wrench says this is the first time he has seen this issue on this car. Searching online I don't seem to find any people with this model or engine model with crank pulley problems.

krazzdav

Yup that is definitely off! Just glad it's confirmed now.
I wouldn't worry about something else causing the balancer to shift but rather it was just worn out and does happen occasionally on all cars---it just isn't often. What I find strange is how good the elastomer ring is (rubber between the inner and outer).

Lesson learned for anyone else that reads through this thread---before changing the timing chain on a running vehicle, align the timing marks prior to taking the chain apart to verify there isn't another problem like the balancer being bad.

jpman take this as a blessing in disguise...if it shifted that much it was just a matter of time before it totally disintegrated and caused engine damage.

So now the question that remains...if you had it aligned to the marks and had valve interference and couldn't spin the engine, how did the mechanic align it to the same mark but could spin the engine?? lol

jpman

Agreed. I intended to check the marks first, but I was trying to get them without the tensioner. Stupid mistake. First step should be, check marks with tensioner on

Confirm top of piston with 0 degree mark on pulley. If I had to start from scratch, I still would have drawn the chain by rotating the crankshaft only. So long as the valves are in the closed position, which I could imagine is when the timing marks of the cams are locked in position with wrenches. The reason I say this is because on the official document from Mercedes Benz they mention to draw the new chain in without the tensioner. I could imagine the only way it won't jump teeth is because they use the tool to hold the chain to the cam gears.

If you run it the way I did, without moving the cam gears, just as long as your valves are closed, and cam gears locked with wrenches you should be able to draw the chain in without interfering the pistons and valves. Then once you have done that you simply lock the cam gears and close the chain. Spin it a couple of time and make sure all lines mark.

This is of course, assuming your pulley has not moved, and your 0 degree mark lines up with the highest point of the piston run.

krazzdav

Nah you didn't make a stupid mistake in not checking the marks first---you just got unlucky that your balancer was one of the few that was no good. But now we know because of the trouble you went through.

I would not recommend anyone changing their chain like you did but now we know it's possible. You got lucky on this point that no valves hit the pistons. The only way to have had the valves in the closed point as you say was to have removed the camshaft entirely. Whatever point the valves were at without holding the cams and in whichever place at rest they chose to be just happened to be lucky for you. Some had to have been partially open while others could have been closed. There are many different positions this could have went.

krazzdav

do you remember where your cam alignment marks were at when you spun the crank? Did you hold the cams at the TDC mark or just let them rest? If you let them rest do you remember where the marks were pointing? This can help someone else if they wanted to take the chance and do it the way you did without the special tool.

jpman

That I don't remember. Its understood this engine is an interference engine, but maybe it only interferes when the valve is in full extension? or in other words fully open.

The way the wrench did it today was set the cams to their respective marks, lock them with a bracket that he has which seems to be the tool in the cam setting document from mercedes. Once this was done he simply removed the exhaust cam gear, and rotate the crank until the crank key notch was lined up to the mark on the timing case. Once done, he just slit the chain onto the intake gear, then added the chain to the exhaust gear and attached the exhaust gear and tightened the bolt that holds it. This ensured the engine was at TDC, the cam gear marks were dead on. Then he rotated the crank a couple of times to make sure the drives kept timing. I believe that he did a full 360 degree turn on the crank while he had the cams locked with their respective timing marks aligned, at no point whatsoever that I hear metal against metal.

Now does the engine work, well we will see tomorrow

What I could say that if the engine had a bent valve, or something went wrong, I believe we would have heard metal against metal noise as we turned the engine. There was none of that.

jpman

ncmudbug

The pulley is comprised of three parts. The inner diameter which attached to the crank, the middle ring which is an elastomer (which in itself is the damper itself) and the outer ring diameter which is what touches the belt. These things happen. Maybe mine was made on a sunday, maybe someone before I had the car did something to the actual crank pulley. One thing is for sure, the bolt was intact which points to it never being touched.

The thing to learn is, confirm 0 degree on the pulley with the piston being at the highest point.

jpman

krazzdav, Thats true, some valves had to have been partially open unless the camshaft itself had been removed (which was not the case). This would lead to believe that there is only interference when the valves are almost at full extension. Cant confirm, just a theory. Lets see if she is the same as she used to be as before.

ncmudbug

I compared the new pulley against the old one it it really has slipped! So the serpentine belt wraps around the outer surface of the pulley and it could slip with respect to the hub? You'd never know unless you went through the pain you did! Maybe it should normally be replaced with the chain.

jpman

Yeap, it has gone around one time at least. I compared it to the new pulley and the thickness of the elastomer is much smaller, it has shrunk. I wouldn't go as far as replacing it with every timing chain replacement as it doesn't seem to be a common issue on these cars. However, I would check it every 100k miles on the car.

jpman

Update, the car started on the first turn with no metallic sound and or hiccups.

Here's a video of a startup after I got home.

Please excuse the broken intake tube. Planning on ordering one as we speak.