wsybert

Height won't matter, as long as he has full engagement of the key. The key is in shear and what does matter is cross sectional area. You would be amazed at how much force that key can take in shear.

sknight

"Aftermarket" is the key here. Parallel keys are not typically used stock to increase the strength and longevity of the crank and to avoid cracking and/or splitting over time, either by loads placed on the crank via the pulley, or thermal cycling and tolerances. The smaller stock keys have proven strong enough for decades now, and also proven to not induce problems of their own- such as being significant weak points in the designs of cranks, leading to their destruction.

c32AMG-DTM

Just to add... my understanding was that the woodruff key wasn't really intended to withstand the shearing forces imparted by a loose crank pulley. Tightening a fresh OEM crank pulley bolt to 200 nM, plus an additional 90* turn, is the only way to ensure that it is torqued sufficiently and properly. Other installation methods (i.e. impact gun) might work, but how do you verify the bolt received the proper torque? If you gun it to 200 Nm (around 150 ft lbs)... you haven't even come close to the actual spec.

GT-ER

You are correct...the woodruff key isn't designed for high shearing forces. It relies on a high clamping force to allow for the shearing forces to be as low as possible. In my case I doubt I can get to high clamping force due to the shaft being worn down...so I now need to rely on something that can take high sheering forces. Another thing is that the oem system is designed to allow for easy disassembly and reassembly with generally zero alignment issues. The parallel key will usually clamp on pretty hard and usually makes a puller necessary. I may also take more than one try to make sure the pulley doesn't wobble.

Again...I'm not saying this is BETTER than oem. It's just better than a new crankshaft or engine ( hopefully anyways ).

c32AMG-DTM

Our definition of "easy" must be different. But I get your point. Good luck with your repairs. Saw in the other thread that you're supposed to torque EC's pulley to 275 ft/lbs (373 Nm), plus the additional 90* turn. That's gonna be tough... good luck; keep us posted on how it goes.

GT-ER

Yes...getting to 275lb-ft is hard enough...the additional 90* makes you think you're going to break the bolt!

Quadcammer

oh bloody hell.

you cut a slot into your crank with a DREMEL in situ?

sometimes its better to cut your losses.

WayneE

Am I correct in assuming that the wobble is caused by not bottoming the hub on the crank snout?

Can you post a picture of the inside of the hub/pulley, where it mates to the front of the crank snout? Is the keyway on the hub/pulley f ucked up? (can't believe f uck is censored)

How are you installing the hub/pulley? Pulling it on with the bolt? When installing, are you not aligning the keyway properly with the key? How are you keeping it from moving before engaging the key in the keyway on the hub/pulley?

sknight

Seriously, can you stop being so insensitive? Imagine how the world would be if we were all nicer, like Care Bears.

Worth the wait

I get that you are trying to fix it yourself without having to replace major engine componets. Further, you acknowledge that this is not the "correct" fix.
Regardless of wether I believe this is the right move or not, I can't help but think of the next guy.......

Provided you can actually get this to hold, When you eventually sell the car what are you going to tell the new owner?

Good luck!

jcjmw

Wow!!! That is a very simple and BRILLIANT solution to a big A$$ problem!!!

sknight

Does anyone else notice the new damage on the front of the engine case?

wsybert

Looks superficial to me.

sknight

Including the ones on the machined surfaces?

slownrusty

Agreed!!

Install that new oil seal, button her up, go for a spin (pun not intended) and you can put an end to all the psychic readers on this forum.

jmb614

Good luck.

benz_addict

how much do new crank bolts go for? Mine came with the pulley

wsybert

Yep. Unless the seal I.D. is damaged to the point it will leak, which I doubt it is, based on what I can see. The machined area on the face doesn't do anything.

sknight

Well, using a screwdriver to pry the crank off doesn't look especially nice.

MBTEK

So here's my .02,if when you orig. replaced the key,didn't replace the whole key,just kinda made your own to fit the area that broke and installed the pulley I'm not suprised it broke again.To do this repair correctly you should be replacing the whole key not part of it,a modified keyway like the one you're doing would really be strong.That may mean pulling the front cover off ,timing chain gear,etc.,I think that will be the end all solution.Having done 60+ pulley swaps on benz's,I have never seen these problems personally,I would would also rec. that to you and all others when installing a pulley on these cars,heat the pulley snout and it will slide on easier.Trying to run the pulley down with bolt does put excess strain on the keyway and failure is more likely to occur.I would also apply some sealant in the keyway area at the end to prevent any oil leaks,checking the pulley balance is also a good idea as JAKPRO mentioned,best of luck and keep us updated,although I fear you may still have problems(fingers crossed).Also for info purposes, there is only 1 key for both pulley and timing gear,part # n 006888 005005.

komp55

Wouldn't the heat make the metal in the pulley snout expand and actually decrease the size of the opening? I don't see how heating it would help, but I also don't doubt what you're saying. I just don't get how it helps?

MBTEK

You are heating the pulley snout,which expands,then allows it to slide over the crank easier.heat= expands,cold= retract/shrink.

WayneE

I've done this on SBCs - works great.

Hotrod-Realtor

Same as a cylinder sleeve for an engine block. You put the sleeve in a freezer to make it smaller. Both the inside hole and outside diameter shrink. Same here on the pulley, the heat expands the inside hole and outside diameter but you did ask a good question. You were probably thinking that if the metal expanded it would close the hole slightly?

KLR CLS

Anybody else notice this guy has nothing helpful to say ...ever! We hear you..... Nobody but MB techs should work these cars........ and they should only be driven on the Autobahn! Why don't you save everybody the trouble of reading your constant negative attacks or attempts to come off as an authority on the engineering on these cars.

Since you don't think a parallel key or pinning the crank is acceptable, what is your solution? Have you ever personally dealt with this type of issue before? What do you think the MB solution would be for this? They would tell you to replace the motor. Dealerships techs are parts changers, thats it ( some good innovative guys like MBTEK are out there thankfully). You seem to bash the common aftermarket solution to this type of problem, an aftermarket which is responsible for some incredible feats of engineering. Look no further than the Texas Mile thread for proof of what aftermarket engineers are capable of.

You sit there and criticize tempts to come up with a creative solution to a problem that this guy is going through. If you don't have anything helpful to add screw off already...