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What do I do if I discover the cams are out of alignment when I open her up?
If the cams are off much, then that's easy - you get another engine, because that engine is trash. The M271 is an interference design.
Once you start pulling the new timing chain ends towards each other, that will lock the position of position of all of the sprockets into some alignment.
Therefore, you need to lock/hold the cams when you install the timing chain. You can have 2 people bite down on the cams, holding them, if that's your thing. But, the cams must be aligned when the timing chain is installed. If the cams are rolling around playing footsie when you're installing the master link into the chain, then who knows what the alignment will be.
Just a tip to anyone who is planning on doing this job and doesn't have access to the chain riveting tool. Febi Bilstein and Swag supply these links to Mercedes m271 timing chains. Part number is; febi 34729
Just a tip to anyone who is planning on doing this job and doesn't have access to the chain riveting tool. Febi Bilstein and Swag supply these links to Mercedes m271 timing chains. Part number is; febi 34729
Fwiw, that has to be one of STUPIDEST Moronic Ricer products that I've ever seen.
WHEN, *not if*, those STUPID clips fall off, the timing chain is broken, and NOTHING OF THAT ENGINE WILL BE SALVAGEABLE - NOTHING! The engine will immediately die. And, for the ~1% of the people that have manual trannys, their rear wheels lock, any vehicle behind them will soon likely be "very intimate" with the car.
I don't know what Bilstein has been doing since the early 2000's. It's hard enough keeping track of the American mergers/etc.
Fwiw, spend the SUPER MASSIVE $100, and DO IT CORRECTLY!! Or, don't waste your time and money. Buy a Honda.
As you know, most companies will gladly sell cr*p to people.
Fwiw, I do not give a flying ****ck if someone used those cr*p product, and their engine "still works". Show me photo proof of when they were installed, the mileage at the time, and the mileage now. Or, take your ricer cr*p and shove it.
Red, don't motorcycles use master links like that? (the clips are different TBF) - the torque on the mc chain has got to be greater than on a timing chain...
Fwiw, that has to be one of STUPIDEST Moronic Ricer products that I've ever seen.
WHEN, *not if*, those STUPID clips fall off, the timing chain is broken, and NOTHING OF THAT ENGINE WILL BE SALVAGEABLE - NOTHING! The engine will immediately die. And, for the ~1% of the people that have manual trannys, their rear wheels lock, any vehicle behind them will soon likely be "very intimate" with the car.
I don't know what Bilstein has been doing since the early 2000's. It's hard enough keeping track of the American mergers/etc.
Fwiw, spend the SUPER MASSIVE $100, and DO IT CORRECTLY!! Or, don't waste your time and money. Buy a Honda.
As you know, most companies will gladly sell cr*p to people.
Fwiw, I do not give a flying ****ck if someone used those cr*p product, and their engine "still works". Show me photo proof of when they were installed, the mileage at the time, and the mileage now. Or, take your ricer cr*p and shove it.
Ehm. Ookay. Pretty aggressive. Are you well?
(Similar chain links have been used for ages in many different applications)
Red, don't motorcycles use master links like that? (the clips are different TBF) - the torque on the mc chain has got to be greater than on a timing chain...
Yeah. Mercedes used them in the past also, on the W116 for one. Alfa Romeo have them in their timing chains, Cadillac have them. It seems pretty common. Just install the closed end in the direction of travel and it should be fine.
Another one bites the dust. 236000 kilometers, I think it's the original chain. Sprockets seem in good condition. Chain tensioner is very tight, almost can't lift it at all.
Just a question before the new chain arrives. Is the chain the length of an even number of turns on the crank? When feeding the new chain through, I guess I have to turn the crank an even number of rotations so I don't end up being 180 degrees out. I other words, I'll end up connecting the new chain together at the same spot where I took the old chain apart, with an even amounts of turns on the crank? Do anyone understand what I'm talking about? 😆
I wonder, though, if it's possible to just drag the chain without turning the crank? Some valves would be open when one piston is at TDC...
You do need to turn an even # rotations, there have been a couple reports where folks ended up 180 degrees out of phase (I think due to their harmonic balancers slipping and them eventually losing count)
Originally Posted by Pexen
Another one bites the dust.
Chain tensioner is very tight, almost can't lift it at all.
Did it blow up or..?
Might just be in a lucky spot where it seems tight, but could start skipping as you rotate the crank.
I wonder, though, if it's possible to just drag the chain without turning the crank? Some valves would be open when one piston is at TDC...
You do need to turn an even # rotations, there have been a couple reports where folks ended up 180 degrees out of phase (I think due to their harmonic balancers slipping and them eventually losing count)
I don't think it's possible. There is no room under the chain to fall, I've checked some videos where all of the front covers are off and there's not room to get enough slack on the chain below the crank sprocket. Everyone I've seen that has done it has locked the cams at tdc and then turned the crank and fed the chain through. There has to be enough clearance for the valves at TDC or else it would not be posssible to do it the way I've seen.
So I guess the chain is the specific length of an even number of rotations on the crank? So that you're able to connect the ends of the new chain without being 180 degrees out.
Edit; I've now checked how it's possible that no valves hit the piston when you rotate crank without cams turning. The m271 has a special design on the crank. When piston 1 is at tdc, so is piston 4. And #2&3 are at bottom dead center (BDC), then the valves are only open a fraction, so little that the piston doesn't hit. The m271 also uses hyudraulic lifters so the valves does not open as much with no oil pressure turning by hand, as they do when car is running.
Edit; I've now checked how it's possible that no valves hit the piston when you rotate crank without cams turning. The m271 has a special design on the crank. When piston 1 is at tdc, so is piston 4. And #2&3 are at bottom dead center (BDC), then the valves are only open a fraction, so little that the piston doesn't hit.
Fwiw, that's completely incorrect, and doesn't even make any sense.
Imho, it'd help you a lot if you understood the basics of how a 4-cycle engine works.
There are plenty of books that describe engine theory, operation, and design - both for 2-cycle and 4-cycle engines.
Good luck.
I have neither the time, nor desire, to argue against doing things that go against the factory, and/or the factory service manual.
Red, don't motorcycles use master links like that? (the clips are different TBF) - the torque on the mc chain has got to be greater than on a timing chain...
Actually, the first thing I thought was "WTF, this isn't some motorcycle chain"!
A bowling ball (without the finger holes drilled in it), a pool/billiard ball, and a roller bearing ball are all "*****".
However, they differ greatly in their design and their properties.
There are real life considerations in the design of anything.
To greatly over simplify things, the M271 timing chain was not designed to use that type of "snap together" Master Link.
Imho, for more detailed reasons, it gets easily into graduate-level Mechanical Engineering.
Actually, the first thing I thought was "WTF, this isn't some motorcycle chain"!
A bowling ball (without the finger holes drilled in it), a pool/billiard ball, and a roller bearing ball are all "*****".
However, they differ greatly in their design and their properties.
There are real life considerations in the design of anything.
To greatly over simplify things, the M271 timing chain was not designed to use that type of "snap together" Master Link.
Imho, for more detailed reasons, it gets easily into graduate-level Mechanical Engineering.
I'm sure the original chain was not designed to be used with timing chain circlips. But that's not relevant because I'm not replacing it with an original chain from 2005. I'm using a new Febi Bilstein chain and they supplied me with the circlips to it.
Mercedes has used these circlips on other cars timing chains, from factory. So does Cadillac and other brands, still today.
You obviously didn't know about it, and that's fine. But chill.
And it's humorous that you say my explanation of how it's possible to turn the engine without the cams turning is incorrect, when you yourself give the exakt same explanation in this post; https://mbworld.org/forums/c-class-w...ml#post7536052
I don't have any interest in beefing with you over this matter. Have a nice life.
I would like to prime the oil system properly before starting it with the new chain in place. I guess I can just leave the coils unplugged and crank it with the key?
Interesting failure on that pulley!.
It might be worth marking a line on the pulley between the keyway and the O/T mark, so any movement of the elastomer section can be picked up?..
Hi,
I have a leaking set of cam magnets. No oil on harness side of pigtails.
I’m being informed that is because of a failing timing chain.
I was under the impression these are not related instances and the cam design is poor, thus the leaking.
A bit late to the party, but the magnet sensors the dealer installed under recall had the same manufacturing flaw as the ones that were replaced. The problem is actually caused by the rubber gaskets between the brown donut sensor and the metal casing losing their flexibility and breaking into pieces.
The solution is to either installed updated senrsors (I heard they updated the gaskets in recent years), or simply open up the metal casings and add a circular ring of RTV on both sides of the brown donut. Knowing what I know now, I would've gone the latter route. The latter fix costs 2% as much as the former and does the same job.
Last edited by slammer111; May 17, 2022 at 08:33 PM.
Hi, for anyone that has done the timing chain replacement. How well do the inlet ('B') and exhaust cam adjuster markings line-up with the TDC mark on the harmonic balancer, with the new chain?
I have inspected mine, and the inlet side and TDC mark line-up perfectly, but the exhaust side is very slightly (~1mm) to the left of the marking. Just wondering whether this is anything to worry about?
I noticed the MB picture shown, they only show the inlet side as lining up, curious why they didn't bother to show the exhaust side cam adjuster?.. TIA..
Hi, for anyone that has done the timing chain replacement. How well do the inlet ('B') and exhaust cam adjuster markings line-up with the TDC mark on the harmonic balancer, with the new chain?
I have inspected mine, and the inlet side and TDC mark line-up perfectly, but the exhaust side is very slightly (~1mm) to the left of the marking. Just wondering whether this is anything to worry about?
I noticed the MB picture shown, they only show the inlet side as lining up, curious why they didn't bother to show the exhaust side cam adjuster?.. TIA..
Hi there, just wondering if you ever got an answer to your query above? On checking my original chain at 95k miles, I find the exact same thing - really tight chain and good teeth on adjusters - and am wondering if it's worth replacing a chain to correct a 1 mm gap between the arrow over the camshaft and the mark on the exhaust outlet.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
(I think due to their harmonic balancers slipping and them eventually losing count)
The problem is actually caused by the rubber gaskets between the brown donut sensor and the metal casing losing their flexibility and breaking into pieces.
