Hogger

2003 Kompressor M271 with 116,000 miles.
Has started having rough starts, and some rattling at start up.
The other day I went to start it, and there was a metal clanking type sound as it turned over, but it didn't start. Tried turning it over again, and all I heard was the starter spinning.

I pulled the starter, and had it tested. All good there, teeth in good condition, bendix engages, and flywheel teeth look good.
I'm thinking it may be the timing chain, after reading about the rattles until the oil pressure comes up.

If the timing chain snapped, would you just hear the starter spinning?
Is there a way to test if the timing chain is bad?

sammydragon3

only way would be to tear the engine open and look at the chain

but u dont know for sure thats the problem...accessory belt, belt tensioner, a pulley could be the problem

timing chain is gunna be like 500 dollars ...part is 100.. labor is like 4 hrs or more

i'd replace the chain at ur mileage..people on here said their valves got bent from the chain at like 60k miles

Glyn M Ruck

Lift the cambox cover & check the chain. Try & turn the engine over manually with a spanner on the crank pulley nut to see if valves are striking pistons. Sounds like the chain has let go.

LILBENZ230

Hopefully your engine isn't terribly damaged if the chain let go during start up.

Hogger

I sure hope it's not bad either.

Glyn, you wouldn't happen to have a diagram of the cam box cover? I couldn't find anything searching, or a DIY.

From what I can tell, I need to pull the coils and plugs, then remove the valve cover. After that I can remove the front cam cover?

If that's the case, I'm going to change the little gaskets around the spark plug holes. Found oil when I changed the plugs. Now I need to find that write up too.

Also, is a chain from Autozone, or NAPA OK? Or should that be something I get from the dealer?

Hogger

Got it exposed, but not sure what to do now. I thought it might have been broken, but it feels tight.
The guide in the center is a little worn. Is the sag normal, or is the chain stretched? Do I need a new valve cover gasket after removing the cover? Or can I re-use the one in there?

Hogger

Here's a couple more. Tried to get the side guides.

Javvy

nice pictures, I am no expert on the TC's but that saag looks bad man.....It should be tight...try lifting it...if you are able to easily lift it...then I would say they are streched beyoud recovery......the chain is suppose to be tight to be bale to sustain the power generated by these v6's.....again some one can chime in, but to me they look pretty streched....

javvy

Hogger

It's on an M271 Kompressor, but ya. I'm thinking the sag is a little excessive.

Hogger

So, does it need to be replaced?
How will I know if the tensioner, and guides need to be replaced?

Called 4 different MB dealers, and they all had different prices for the chain alone. From $124 to $269.
I found on NAPA they have the chain, tensioner, and guides for $278, from Altrom Imports. Think it's safe?

Glyn M Ruck

You obviously got it off. Please use a genuine chain.!

Glyn M Ruck

Your timing chain is in big trouble. I'm merging threads!

Glyn M Ruck

OK. You chain has no tension & is stretched. We don't know if it has jumped a tooth. Can you turn the engine over?

What do you intend doing? Repair yourself? Or go to an Indy. You need to at minimum draw a new chain through & tension & check the valve timing if the engine will turn over.

If it were my engine I would strip the front end & do a new balancer chain, primary chain. Check the guides & fit a new tensioner and anything else thats worn including sprockets (only if worn).

The cheap way is to pull a new primary chain , tension it, check the valve timing & pray.

Good luck!



11 A 271 052 11 16 SLIDE RAIL
(CLAMPING RAIL) 001
14 N 000000 0002102 SCREW
TENSIONING RAIL TO CYLINDER HEAD 001
17 A 271 052 10 16 SLIDE RAIL
AT CYLINDER HEAD 001
20 N 000000 0002102 SCREW
SLIDING RAIL TO CYLINDER HEAD 001
23 A 000 997 64 20 EXPANSION PLUG 002
26 A 271 052 04 16 SLIDE RAIL
TO CAMSHAFT BEARING HOUSING 001
70 A 271 052 06 40 HOLDER
CHAIN TIGHTENER TO CYLINDER CRANKCASE 001
75 N 910105 5008014 SCREW
CHAIN TIGHTENER TO CYLINDER CRANKCASE
M8X35 002
130 A 004 997 25 94 ROLLER CHAIN
LANCHESTER BALANCER, WITH LOCK
Replaced_By: A 000 993 20 76 001
130 A 000 993 20 76 CHAIN
LANCHESTER BALANCER, WITH LOCK 001
150 A 271 030 08 63 CHAIN TIGHTENER
LANCHESTER BALANCER 001

Hogger

Glyn, again, your knowledge, and information is amazing.
I really appreciate your help. You've been instrumental in my last couple of projects.

Thank you!

I plan on doing the work myself. I've got most of the parts ordered from a couple different dealers. So now I have the weekend to tear it down while I wait for parts.
It doesn't start. I initially thought my starter was bad, so I pulled it out and had it tested, but it's fine. So i started looking toward this timing chain issue after the rattles on start-up.
I'm going to try and turn it over by hand to check the valves like you suggested.

Hogger

Well, the engine turns over by hand, but I'm not sure if I'm turning it the right way.
More questions.
1. Which way should I be turning the crank bolt to turn the engine? Clockwise, or counter clockwise?
2. And which way to loosen it?
3. I'm trying to hear if the valves are hitting the pistons. Will I just hear a little metallic click? How can I tell if valves are bad without removing the head?
4. Which side is intake cam, and which is exhaust cam? Guessing intake on right side since that's where the intake is, and exhaust on the left since that's the side the exhaust manifold is on.
5. To replace the guides, do I have to remove the front timing chain cover? Or is it possible from just removing the top U shaped piece?
6. How about the tensioner, does the front cover have to be removed to change it out? Or just remove the alternator.
7. How does the tensioner have to be set? Is there a specific length, tightness, etc...?

When the crank is at TDC the notches on the cams are not lined up with the arrows on the cam housing. Shouldn't they both be lined up at TDC?
I guess it did jump teeth.

Glyn M Ruck

The chain has jumped. I would really replace both chains on this engine.

Hogger

Thanks Glyn.
I was rotating the engine and the chain was jumping the exhaust cam. I think I saw it jump intake cam too. Now I rotated it more, and it stops. Like something is catching, or blocking it. I did turn it counter clockwise earlier, but decided I better wait and find out for sure, only maybe 1/2 a turn.

When you say guides, are you referring to the orange chain guides, or valve guides?

Carsy

Hello Hogger,

IMHO you will need a detailed guide ie workshop manual to work you way through this.

Good luck,

JC

Hogger

I decided to call a shop and get an idea for repair costs, I am feeling a little frustrated at this point. Talked to one mechanic, who quickly told me it would be unlikely that there WOULDN'T be damage to the valves or rods, or both. He even thought replacing the engine might be easier.
Without knowing exactly what damage I have, what is likelyhood that I will need new rods/valves, and is a new engine a better route. A new engine will not be worth the value of the car, it might be better to part it out. But if there is still hope of repairs, not involving a replacement engine, then I am all ears. Can you hear the anxiety in my voice? 2 weeks ago I had a perfect running vehicle, now possibly needing MAJOR repairs. Please give me all your professional input.

I don't have a service manual, but I've done a lot of work on cars, trucks, and marine engines. I feel I shouldn't have too much trouble doing the work with a little help here. Plus, I love the challenge.

I really appreciate everyones time you put into responding. You are a huge help!

Jordan

Carsy

Right O, with your experience , a workshop manual & time you should be able to do the job well.

I understood from this forum that in the USA you have access to the manual on CD's from the dealer.

Otherwise you will have to find some kind person on this website with WIS who can transfer the info easily to you . I have it but need to print it out then scan it then attach it. There will be quite a few pages of info that you will need.

As Glyn says whilst you are at it you should replace the other chain , the chain guides
& any other worn parts.

If it were my engine I would avoid removing the head to ascertain whether there is any damage until I could check with a scope through the spark plug or by timing the engine again & rotating it by hand to see whether there are bent valve stems.

Back yourself & have a go but first find out the extent of the damage & therefore the cost of repair. You can them make a decision on whether it may be cheaper to find another engine or scrap the car.

Keep us informed.

Hogger

Ok, so I know it's out of time right now since I saw it jump teeth when rotating it by hand, and it won't rotate now because it jumped so far that now the valves are hitting the piston.
So I'm thinking if I can undo the master link, or loosen the chain enough, I can get the crank and cams set back properly by hand. Then re-link the chain and try and keep it tight while rotating the engine and looking with a scope to see if the valves are hitting.
This should let me know if the internals are shot, right?
Sound plausable?

Glyn M Ruck

You can try that but I think you almost certainly have a few bent valves if you hit tesistance while rotating. I was talking the plastic guides. In most cases with the M271 the pistons & rods survive just fine & valve replacement & seating is all that's required. The only & obvious exception is a chain letting go at high RPM under load.

Obviously with the head off it pays to replace valve stem seals. Reseat all valves nicely & inspect valve guides for damage where valves have bent.

BTW - I'm hoping that someone with the R&R CD can post the whole method for you - splinter, Johnand help! I've never torn down an M271 - bit of a theory man I'm afraid although I've had many Benz & other engines apart. I know that the chain tensioner is a use once device that you release per the method once - when you have everything aligned & timed. Any further fiddling can lead to over tensioning & rapid initial wear with dire consequences.

splinter

M271 cylinder head R&R

Hogger

So I grabbed a borescope today and started poking around.
In cyl. #4 I found both exhaust and intake valves down on the piston. BUT after the chain jumped teeth when turning it by hand, I can see how they got in that position.
Now the bad part. On the top of two of the pistons I found where the valves have left indents.
Sorry the pictures aren't great, but at least the scope takes them.

I don't think the dents have worked into the cylinder wall, but I'll have to take another look at each dent, and cylinder.

So, I think I'm beyond just pulling the head and getting new valves.
What do you guys think? New engine? Rebuild? Is it worth it?

Hogger

After a closer inspection. All pistons are dented from the intake valves. I might have one or two dents on the exhaust side, but if they are, they are very small.
A few more pictures. Two of dented pistons, and one of the dents showing the cylinder wall, taken from the top of the piston.

This is a fun little tool!