Cracked crank pulley, worn woodruff keys, crank

[Oddmanout84]

So it started with my last thread here about finding my timing chain guides worn. While taking the engine and everything around it apart, I found this:

 

 

The crank pulley rotates several degrees independent of the crankshaft. So being upset already at finding other things, I pulled it off to see what was going on. This is what I found next:

 

 

The crank pulley is visibly cracked, but it doesn't end there. On the crank the woodruff key was sitting loosely in its slot. It slid out easily with my fingers.

 

 

As you can easily see, the woodruff key looks like its been wobbling back and forth for a long time. I have a spare L28ET crankshaft sitting on my workbench, so I pried off another key to see if the wear extended to the crankshaft slot. It did. The key fits easily into the slot and wobbles around. The slot is larger than what it should be. Not good. I don't know how this has happened, but the bolt was tightly on the crank when I installed the motor. Now its not.

 

Is my crank screwed? Do I have to pull my crank and install another one? I'm already in the pit in terms of money that I didn't want to spend this month, but this looks to be yet another thing that's going to se me back. I don't even have an engine hoist here, as the nearest friend I have with one is 200 miles away and I have no means of getting it without a car to drive. If anyone has input, it'd sure be appreciated...

Edited April 28, 2010 by Oddmanout84

[josh817]

Time to acquire tools my friend. Maybe find a Harbor Freight. My dad bought an engine hoist for like $80.

 

My point is, that crank snout is dead. And if it saw a lot of miles and some higher RPM's with that bad key, bearings may be dead too.

Edited April 28, 2010 by josh817

[h4nsm0l3m4n]

If your pulley is cracked I'd invest in a new pulley. As far as the crank keyway being worn if youre looking for quick fix for the problem you might try this: http://www.miata.net/garage/hsue/LoctiteCrank1.html

I actually just had the same problem a couple weeks ago and used the same procedure as outlined in the above link. It seems to have worked very well and should hold until I have time and money to properly rebuilt the motor with a new pulley and crankshaft.

Edited April 28, 2010 by h4nsm0l3m4n

[woldson]

LOL, been their done that.

 

Now, the crank was so much harder that it was not an issue. I can not see your crank keyway very well.

 

My damage was an installation problem that haunted me for some time untill.......

[cygnusx1]

I did the locktite thing on my turbo Z a few years ago.  Seems to be working.  When it fails, I'll put in the new crank I have and rebuild the motor.  Just check the pulley bolt every month or so.  That's how they fail.  The bolt loosens and the pulley wobbles the keyway to death.  By the time you are aware of it, it's too late.

[josh817]

I like how everyone responds with a simple solution. I guess I'm not one to rig something up, but then again, when money is tight, do what you have to do.

 

Another thing you may check out is Devcon filler. Two part filler like bondo, they come with a titanium version or something. They use it to repair nuclear reactors and ****! Hahahaha. Its expensive, but you only need a little. I think they may come in the little syringe tubes like you see the with the plastic glues. A pound of this stuff is $100 though I believe. Search Google for "Devcon", its good stuff, I think they also use it to MAKE bolts for those giant applications that the bolt is a special order and they need one now. Make it out of Devcon, it holds up to the torque.

[Oddmanout84]

Time to acquire tools my friend. Maybe find a Harbor Freight. My dad bought an engine hoist for like $80.

 

My point is, that crank snout is dead. And if it saw a lot of miles and some higher RPM's with that bad key, bearings may be dead too.

 

Yeah, I've been looking to get a hoist for quite some time. But now was not supposed to be the time.

 

 

LOL, been their done that.

 

Now, the crank was so much harder that it was not an issue. I can not see your crank keyway very well.

 

My damage was an installation problem that haunted me for some time untill.......

 

Yeah, its really hard to see the slot in the crank. Its not absolutely terrible, but it seems widened a bit due to the wear. Thanks for the responses, guys. Its a bit early to tell, but I imagine I should be able to see it better when I remove the timing cover. Hopefully its as simple as putting in a shim or locktite... but I dunno...

[hoov100]

Just get a new key and pulley and run it. if the crank is indeed screwed up, you might as well try and run it until it needs a rebuild.

[Oddmanout84]

The sad thing is, this motor only has about 5000 miles on it since its previous owner rebuilt it.

[garvice]

I had a similar issue, but from completely different cause. The previous owner of my engine decided that a $100 stock pulley was too expensive for the L28 that he rebuilt. So he decided that a welded harmonic balancer was the go. It destroyed the key and keyway like you have shown. When I pulled the crank the bearings were scored/worn as well among other issues. Sorry to be the bearer of bad news but you may have other problems too.

[josh817]

I don't know the specs on Locktite but this Devcon epoxy does 2500psi and its $2.

 

http://www.antonline.com/p_60020-GP_590189.htm

[Oddmanout84]

The oil pump/dizzy drive gear didn't want to come out, had to file down the ridge that was formed on the crank.

 

Other than that, it looks like a shim and a bit of JB weld may fix this for now...

[yetterben]

Thats a disaster waiting to happen man. If yah need a crank let me know.

[BRAAP]

You guys forgot the most important aspect of why the damper is used in the first place, crankshaft fatigue.

Typical problems associated with a loose damper or one that has the inertia ring that came loose is a cracked/fractured/busted crankshaft, generally starts out as spider cracks in the radius of the rod journals, also sometimes in the main journal radius. To know for sure you'll have to remove the crank and have it inspected. Sometimes the cracks can be seen in a visual though a Mag test will reveal the hard to see cracks. If cracks are present and you continue to run it, those cracks will continue to grow to the point of failure at some point down the road. Could be several thousand miles later depending on many factors.

 

Sorry, but if it were my engine and I was planning to run it as my daily driver or race car, I'd start with a different crank.

[Tony D]

The sad thing is, this motor only has about 5000 miles on it since its previous owner rebuilt it.

 

This is why I say not to 'rebuild engines' because with someone saying this engine was 'rebuilt' 5000 miles ago...well it is a prime example of being worse off than what they started with!

 

The loctite is not a 'temporary fix' or a 'rigging' it's recommended from the get-go when rebuilding. Cylindrical locking compounds help retain the mating surface, and when installed correctly do not cause an issue upon removal, given proper procedures. Nobody here has mentioned the KA24 Crank Snout Bolt and Washer Upgrade---if you use the same bolt and washer over, this WILL happen again, especially if you rev the longer-stroke of an L28. The torque pulsations from each cylinder hitting are big, and will loosen or work that crank snout hard. Longer Bolt + 1/2" Thick Hardened Washer = Pulley properly clamped to the crank snout to prevent fretting in the future.

 

There is no reason to pull the engine, crank service can be done in-frame. If it bothers you that much, with nothing more than a floor jack and some 2X4 blocks you can get the clearance to pull the crank out from the bottom. Yeah, it sucks doing it on your back, and in some cases laying in dirt and mud...but you can do it. If money is as tight as you say, then save the money on the lift rental, do the job in-frame (Norm the 12SU Dude described the process elsewhere...as well as how to PULL the engine out the bottom without and engine hoist!), and save that money for the Magnaflux Crank Inspection Braap discussed.

 

This is not the end of the world, just a shuffling of time from one priority to another. If you don't have the little bit of money now for an inspection....will you have the massive money later for the possible wreck that may occur?

 

Last point to ponder----if this guy says he rebuilt the engine and you found THIS....WHAT ELSE LAYS INSIDE UNOTICED??? Sounds like the biggest reason of all to pull the engine down and MAKE SURE what you have, judging by these photos, you never know what you will find inside when you open it up! Am I the only one with this concern?

[Zmanco]

I think Tony brings up a good point that you should be wondering what else isn't right with this build ...

 

That said, the identical thing happened to me about 10k miles after the engine rebuild. I bought a new damper and crank bolt and used the Miata fix listed in one of the posts above and drove it for another 15k miles before I changed to a turbo motor. I used some white nail polish to mark a line on one side of the bolt/washer/damper so that it would be obvious if anything began to move and then checked it regularly, but nothing ever moved.

 

It's not the kind of fix that any of us would prefer, but if it's the only way to get it back on the road, then you might take a shot at it.

 

BTW, lesson learned for me: always use loctite on the damper and crank bolt from now on!

[Tony D]

"BTW, lesson learned for me: always use loctite on the damper and crank bolt from now on!"

 

What continually amazes me, though, is that 'The Bible' has had those directions written down in it since before I was doing L-Engines. My VERY FIRST pulley replacement was done by the book according to Honsowetz, and that was 1985 or thereabout.

 

Who rebuilds and engine and doesn't locktite the crank pulley bolt, and use cylindrical locking compound? Especially when 'the directions' say to do so?

 

Overkill is one thing, but if you don't know, overkill is a good thing given the consequences.

[woldson]

Who rebuilds and engine and doesn't locktite the crank pulley bolt, and use cylindrical locking compound? Especially when 'the directions' say to do so?

 

Me.

 

Lesson learned though. The "pop" sound upon installation was not just the key ways lining up. You see, if I had done everything correctly then I would not have a smile on my face now.

 

I did my first top end build without instructions, I do love a challenge. Some mistakes are acceptable, for me.

 

Learned about the tensioner the hard way, however, replaced the chain because of it.

 

Knowing what I know now, I may be temped to mic the key for alignment and weld it. Then drive it carefully while looking for another long block.

 

Once that is in hand drive it harder. If it fails, well then you gots ye self a story.

 

The only problem, you are responsible if anyone gets hurt. You have to weigh that yourself.

 

 

Thinking about this more, in lue of information given to you, it might make you look like a dolt. Things that make you go hummm.

[yetterben]

Man i have this vision of the pulley coming off at 5 grand and well going...where it wants to.

[TimZ]

"BTW, lesson learned for me: always use loctite on the damper and crank bolt from now on!"

 

What continually amazes me, though, is that 'The Bible' has had those directions written down in it since before I was doing L-Engines. My VERY FIRST pulley replacement was done by the book according to Honsowetz, and that was 1985 or thereabout.

 

Who rebuilds and engine and doesn't locktite the crank pulley bolt, and use cylindrical locking compound? Especially when 'the directions' say to do so?

 

Overkill is one thing, but if you don't know, overkill is a good thing given the consequences.

 

One thing that Tony has alluded to, but I don't think has been emphasized enough is that the most important point here is the clamping force that the bolt is imparting on the damper. If your bolt/washer combo isn't applying enough clamping force, then all the red loctite in the world isn't going to keep it from failing. This applies to both the stock setup, whose washer is often too thin to give the force distribution necessary, to the Nissan Comp bolt/washer (probably the KA24 combo Tony mentioned but I'm not 100% sure), that has a locating step in the washer that's a few thou too thick and bottoms to the nose of the crank just before it starts putting clamping loads on the damper.

 

The clamping force is what keeps everything held together - the woodruff keys are only there for precise alignment during assembly. When proper clamping loads are present, all of the rotational forces imparted to the lower chain sprocket/oil pump drive/damper come through the frictional interface between the parts, and the woodruff keys see no shear loads. The woodruff keys should never be the thing that's actually causing the damper to rotate with the crank. That only happens when you lose clamping force, and that's precisely when you start having problems.

 

Hopefully this is obvious, but if you are seeing munged up woodruff keys/slots, then you definitely did not have enough clamping force on the damper.

Edited May 14, 2010 by TimZ