Timing chain master link with e-clips
 

I noticed when I ordered a new timing chain for my 560 sel; the master link was not a crimp-type that requires a chain peening tool, but a link that uses two e-clips to secure the link to the chain. I always thought these were just for pulling a new chain into the engine via attachment to the old to draw it through.

My dealer however claims that they use these master links exclusively for permanent applications. A crimp-type is unavailable from this dealer.

I feel a bit strange about having e-clips holding something so serious together as a timing chain. Has anyone had a similar experience or good or bad results with the supposed e-clip master link??? Otherwise, I might have to track down a supplier of a crimped style so I feel better.

Thanks

Adam T. L. Delecki

I felt the same, but used the clips that were provided after encouraging words from a couple techs here. Been 60K+ miles without problem on the 560, and a couple years on the 4.5.

Thanks, I think I'll give it a try. It just looks a bit too flimsy to be spinning around at several hundred rpm. Plus, the cutaways that the clips slide into weaken the link considerably, much more than deforming the crimpable link. I might do this, just with the point to replace the link with a second clip-type in 50,000 miles.

Adam

Using clips is what the 107 shop manual recommended, and I can't beleive that MB would actually document a seriously inferior repair.

My opinion, even if that winds up being the weakest link on the chain, if that breaks, it breaks for some other reason that would have broken any link on a chain without clips!

I used these on my last motorcycle chain. If you think major engine damage is a high price to pay for chain failure, try substituting your life.

Well, I'll give it a try. When I did the chain on my diesel, I was able to get a crimpable master link. Well, this will certainly be a lot easier, but it also makes my crimping tool that I bought some years ago for MB double chains quite useless for this job...

Timing chain failure effectively just stops the engine (permanently) when it occurs. Other than removing power assist from steering and brakes, you can still control the car quite well, just as if the engine would die for any other reason. I had a BMW that died when the timing chain (single) failed at highway speeds. Just turned my blinker on and pulled off the road. The sound of the failure clues you into what happened immediately. The only problem that can occur is the car speed will still try to turn the crankshaft through the transmission if you are not quick to shift to neutral. If for some reason the chain will still try to feed by the crank's speocket, the chain can bind and damage either the crank, the sprocket or worst case the allum block. If this happends, rebuilding is unlikely.

Thanks,

Adam

that is the only type links we have used when replacing the v-8 chains, never a problem

The circlip style chain is perfectly fine on the gas engines. The diesels are a different story however. IIRC MB stopped selling the circlip style for diesels, because of problems with the possibility of failure. Unless you get some old stock, all the diesel replacement chains are the crimp style. By the way you don't need a special crimping tool. Two ball peen hammers work just fine. Most people don't even know why it's called a BALL PEEN. Also don't woory about the reduced pin size where the clip goes, because there is no stress there. Hopefully you have a replacement chain with two small clips. I don't think the single clip style is available anymore. If you have a single clip, the solid end goes in the direction of travel.

Sorry I just reread your post. You have two clips.:o

I would think the higher compression of the diesel will send a lot more vibration/harmonics through the chain than in a gas motor, however I'm not sure the circlip suffers this stress or not.

The V-8s don't suffer from much chain stretch as a probelm with timing, but the guides get sensitive after about 100k mi to any chain slap which if they break off can cause catastrofic engine failure (at least for the top end). I am just replacing the guides and chains as a set for my 100k mi maintenance. Does anyone know if the diesel master link will fit the 560's chain? I might try using this just to make me feel better.

I agree, you don't need a chain press to properly crimp the chain, but it does look a lot nicer than peening it manually. Also, if you do peen it, it is smart to use something heavy like a heel dolly to back the master link when you peen it so the sprocket does not have to take the full load; and yes with a ball peen hammer. The only problem with peening it manually without the factory tool, is that you can over peen the link which will induce stresses into the link, cause excessive friction, and possibly even cause the crimp to become undone over time.

The factory tool will only allow a certain amount of crimp, and with most steels, this actually hardens the metal and makes it less liekly to deform later on its own.

Thanks,

Adam (ATLD)

Adam,
You worry too much. There is no stress on the peened part. It meerly keeps the end piece from coming off. MB designed the crimping tool for uniformity to be sure there would be no problem. That doesn't mean that a person skilled with a peen hammer can't do the job as well. They are just covering their butts as well they should be. I have to disagree with you on V8 chain stretch. They are the only MB chains with a problem, because of their length. They slap the crap out of the insde rail on the left head until it snaps. Every professional sees this as a classic problem. When a V8 reaches about 8* of retard, it's chain time.

By the way, the old style diesel link is different.

I think that it is easy to fall into the mindset that the eclips are all that is holding the tension of the chain. That is just not the case. The tension of the chain is held by the links and plates. The eclip only keeps the plate from sliding off of the link pins. This force is a tiny, TINY fraction of the tension force held by the chain.

Have a great day,

It's true, I do worry too much about machines, but perfection is difficult if not impossible to accomplish unless you are God. Also, most good machines are the product of a worrying engineer, while most bad machines are the product of an overly confident or untrained engineer.

I believe that’s what I said in an earlier post so I'm not really sure about what you are disagreeing about. The chain stretching isn't really the main problem; it’s the brittle guides that fracture with an otherwise not problematic amount of chain stretch (as in not affecting timing etc). Some people have even replaced their chain at 100k (but not the guides) and suffer the same fate. That is why it is always recommended that the chain and guides are replaced together. The chain slaps against the plastic guides that get brittle with age and with some engine dynamics, a part breaks off and gets between the chain and the sprocket and then the top end of the engine is gone. This replacement (chain, guides, and tensioner rail) is recommended for any late 80s or early 90s MB v-8 every 100K mi or more. The design flaw is the brittle guides, though a slacking chain accentuates this problem. I had thought I said this earlier.

I agree that the stresses are minimal for the link trying to fall outward from the chain, but this is true only for static loading. In dynamic loading all hell can break loose and harmonics of the engine's explosions and chains rotation and slapping can certainly cause vibrations that are in the direction axial to the chain's link. Perhaps the e-clips can still hold the link on, but it just makes me feel squeamish.

Ask any engineer, if a structure is exposed to both static and dynamic loading, it’s the dynamic vibrations are the chief concern to structural stability for the long run and the primary factor that decides the structural dimensions to support these loadings. Vibrations are a huge portion of engineering and not one of the easier parts either.

I once taught a dynamics course for turbines and other high speed rotating machines once. You’d be absolutely amazed how much force can be produced from a tiny unbalance (which is inevitable) in any spinning object. The other interesting thing was in what direction are these forces produced, not at all in the directions you’d think. For even marginally realistic problems, huge FEA codes are needed to estimate these loads while even at best the output is still conservative. This is why high speed turbines such as turbochargers require such precise machining. Though, I’ll admit that the chain is spinning at a much slower speed, it is however running in a non-concentric pattern and has a mass far grater than most turbines for small engines.

Again, I don't disagree that MB took this loading into account because these cars were build by some of the best engineers in the industry, but these clips are spinning and sliding around at a couple hundreds rpm; this still makes me worry. I’d still rather have a crimped clip but I guess if there is no other choice, I’ll have to go with it. Hell, they were wrong with the chain guides, so they could be wrong with this too.

ATLD