Cracked crank pulley, worn woodruff keys, crank

[BRAAP]

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 woordruff 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, that that's precisely when you start having problems.

 

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

 

 

As an engine builder/machinist, this is poetry to my ears.

 

Well stated Tim, thank you.

[Oddmanout84]

Thanks guys for all the info. I do know that the woodruff keys are only there for indexing the damper on the crank, and that the bolt/washer combo is whats really clamping it on there with friction. I'd LIKE to think that this engine was built correctly. The guy who made it around 2000(who's also a member of this site) seemed to know his stuff, and put most of his work on this engine into blueprinting the bottom end and using clevite bearings. He seemed to have really good attention to detail with what he did. But we're all human, and I should really pursue this further. Before the motor went into the car I DID crack open the oil pan and valve cover to inspect and check torques. However, that's not going to find possible spider cracks. I have two spare L28 cranks that I could theoretically use, but I'm not even sure that THOSE don't have hairline cracks either. I poked around the internet for magnaflux inspections and even found a few do-it-yourself kits that include the dye and sometimes a blacklite. Would it be worth it to do my own inspection or should I just find a machine shop that can professionally do it for me? Usually, I like to do things myself and can't see this as being over my head, but I could be wrong. Its certainly something important enough to make sure its done right.

 

Otherwise, there's an airport nearby which should have some sort of A&P shop with capability for magnaflux inspection.

[Tony D]

Magnaflux is NOT a 'dye penetrant' inspection process! The kits you are talking about are either Spot-Chek, or Zyglo.

 

The Magnaflux process uses an induced magnetic field in a ferrous component and a magnetic dust shaken on the part---the theory being any crack will give a 'north and south' magnetic pole setup and the particles will align. In some instances these can be INTERNAL cracks close to the surface that have failed to fully propogate to the surface, from a casting inclusion, etc.

 

I wouldn't do my own check on a crankshaft, the charge for a proper maxnaflux and zyglo inspection should be under $50 and that will be done right by someone who knows what to look for on the components.

 

I spot-check Pistons, though. My Zyglo stuff is all out of date, you need a pretty good dark room and shroud to block the light to do that test. I'd just pay the $ and have the guy run the test.

 

Oh yeah, and the 'clamping'---the KA bolt is too ling, but Jeff used that Volvo Washer which was thicker, so it didn't bottom. I have seen people take the ARA air conditioners off, as well as the drive pulley, then screw in the crankshaft bolt---bottoming it out because there's no auxiliary pully under it, making the stock pulley wobble all over and do all sorts of nasty stuff. Sometimes you can even hear the washer rattling at idle (tink-tink-tink-tinka!)

 

This is the same process our company uses to mate centrifugal compressor impellers to their drive pinions, our 'keys' are only there for precision alignment as well--in some cases they are nothing more than a 1/8" spring pin. If the impeller stud 'goes soft' and elastically deforms....that's all she wrote! Wreck time.

 

Of course, those are turning 54,000 rpms, not 7000...

Edited May 16, 2010 by Tony D

[Sam280Z]

I'm in the process of putting together a motor with the KA bolt/Volvo washer mod. I ordered the washers from Swedish Engineering and the KA bolt from Courtesy. Courtesy said they are having so many problems getting stuff from NISMO NA that it wasn't worth trying to get the $40 NISMO set. MSA said it would take 6 weeks for them to get it.

 

KA Bolt & Volvo Washer

 

The pic shows the unmodified KA bolt on the left, the shortened bolt (2.240" total length, head and all) in the center, and the stock bolt on the right. The volvo and stock washers are shown above. I still have to cut the small step to register the washer on the crank shaft. It appears thta I do not have to reduce the diameter as has been reported since I am using a BHJ damper.

[Dgriggs]

I have not seen your pics yet,

But I think I had a very similar situation with a well worn L24 years ago. The crank snout bolt had backed off and the balancer was twisting back and forth so violently on the worn out key and keyway there was a terminal sounding knock coming from down there. At the time I was saving my pennies for the stroker I am currently running.

 

Not wanting any further turd polishing, I fixed it on the cheap.

 

Cheap Solution:

The pulley was removed,

key replaced with a slightly larger (I bought a slightly wider one that need to be filed to fit) version from an industrial bearing supplier,

pulley reinstalled with new key, and crank bolt retorqued using "red death" locktite.

 

This 75 cent fix lasted for 15,000 miles, until I swapped in the L31. Who knows how much longer it would have lasted. I used to rev that L24 like there was no tomorrow!

 

You can replace your crank, bearings etc. on general principle if it helps you sleep at night. However, as it was in my case, you may just need a 75 cent band aid.

 

I know which one I would do again if I had to.

I think I will check the torque on my engine when I get home.

 

DG

Edited May 17, 2010 by Dgriggs

[Oddmanout84]

You guys are making this hard! Lol. My usual anal-retentive self is at war with my desire to get this thing back on the road so I can enjoy the summer driving.

 

Tony- Yes, I'm new to the world of magnaflux but I understood that it required a magnet. I just thought maybe the kits came with a small electromagnet and the "dye" in the aerosol cans had some sort of ferrous particles in it. I was wrong. And you're right, I should just get it professionally inspected instead of trying to do it myself.

 

Upon cleaning and further inspection with the block still in the car, I discovered the cylinder walls of especially #3 and #4 are pitted pretty bad near the top (but below top of stroke). Bad enough to catch a fingernail. Could be because the motor had sat for 4 years in a garage, but regardless the buildup of carbon and oil sludge looks like the rings have lost a lot of oil control. Perhaps I'm going to far in this respect but I figure now since I SHOULD be inspecting the crankshaft, maybe I should just get the whole block out and bore .020 over and get some matching ITM pistons. I wanted to do that at some point anyway.

[cygnusx1]

I vote quick fix and enjoy the car.  Fix it, if and when, it really breaks.   I have been saying to myself, "I need to rebuild my turbo motor" for about seven years now.  In reality, I have gained seven years of use on a motor that was failing in my head.  I hear a tick, see some oil, a drop of coolant, or a rattle, and my imagination runs wild.  Sometimes, leaving it alone is not the bad option. I repeat, SOMETIMES....

[Daeron]

I've kept quiet on this, because my relevant experience was with a Geo, and because I didn't want to write a book about a Geo in response to your situation.. so I will try to be short and sweet.

 

My first car was a 92 Geo Storm hatchback. Pretty sweet little ride, except for the automatic tranny.. 1.6 liter, aluminum block four cylinder, 12 valve single cam head (two intakes one exh I THINK) It had like, 160K on the odometer when I got it upon high school graduation.

 

After four thousand miles, the timing belt snapped on me while driving on I-95. (Turned into a MUCH worse day than that... ugh) I could NOT, for the life of me, over the next two WEEKS, get the crankshaft bolt off; at first the car was 40 miles from my house, at a friends.. Using a breaker bar and a big pipe with the starter motor didn't get it.

 

Took the car to my brother's house and he eventually broke off the half-moon flange that served as the bottom half of the sprocket cover (part of the block casting) to slip the new timing belt on. Eventually the leaking oil seal destroyed this timing belt as well, so THIS time I threw one on, and got the car to my brother's shop where The Big Impact Gun was used to bust the crankshaft bolt loose, and voila!!! Oil seal changed.

 

This is all playing out over my Summer of Freedom and then first year of college, remember.

 

Four thousand miles later the car runs awful again and we find that the whole time, the woodruff key has been wearing out. Replaced the Pulley, bolt, washer, and key all with new Isuzu parts (to the tune of about $150, IIRC) and thought I was FINALLY good to go!!!

 

Four thousand miles later, the pulley had warbled itself again, the timing was slopping back and forth again, and the car barely ran again. The ENTIRE problem had re created itself. (AWESOME AWESOME ENDING THAT HAS TO BE INCLUDED HERE EVEN THOUGH IT IS UTTERLY UNRELATED TO THIS THREAD: My 75 280Z showed up on the corner I lived on.. the guy THREE houses down was selling it.. for $300!! got in and checked it out and saw the four speed shift knob, shofted through the pattern while I was investigating the rest of the intrior, and suddenly, it actually DID pop up into fifth! I was SOLD. Efff the Geoooooo!!!!)

 

 

At this point, the Internets was becoming ubiquitous (finally) and my oldest brother stumbled across a link similar to the one shown in this thread; loctite the living hell outta the crank pulley bolt, pray, hold on, and know that one day your hindquarters shall be bitten again, and the piper shall demand his pay. So we finally realized that some PO had loctited the engine before ever giving us the car... hence all the difficulties.

 

Four thousand miles, though... like CLOCKWORK. Timing belt blew, because the oil seal blew, because the crankshaft had simply been utterly... Heck, I don't even know. This story is my archetypal Unexplained Mystery Internal Failure that Taught Me How To Fix My Own Car. The official diagnosis for the engine in the Geo, in my mind, was simply a word that rhymes with "plucked."

[Oddmanout84]

Well, I finally have the block completely torn down. Here are my findings:

 

Two of my cylinders have pitting in them like this (#3 and #4)from where some moisture presumably accumulated while the engine sat in my friends garage for the four years before I bought it. This was not visible until the head was removed. Hopefully a .020 overbore will fix it, and I have .020 oversized pistons on the way.

 

The multi layer steel head gasket looks like it was leaking between a coolant passage and cylinder #2. Bought an OEM composite gasket to fix, hopefully the fact that it blocks off coolant passages isn't going to cause any issues (have seen varying opinions on the forums).

 

I've now torn down 3 L28's within the past couple months. These are the crank pulley bolts. All are shown in the same condition as when they were pulled.

On the far left is the bolt from my original L28E, its obviously shorter, never gave me any problems. The middle bolt is from my spare L28ET. The far right bolt is from my current L28ET, which I just pulled. Unlike the others, it has a lock washer installed. I've been informed that lock washers are actually detrimental in some situations, like on exhaust bolts, in which they act like springs and can actually loosen the fasteners they're meant to lock. In the case of this one, I'm willing to bet it also prevented the actual torque on the bolt from equaling the indicated torque on the wrench.

 

And the crème de la crème was discovered when I removed the oil pan and began inspection and disassembly. My crank could be moved laterally in the block over 1mm. You can guess where this is going.

 

Thrust bearing front face:

 

Thrust bearing rear face:

 

Crankshaft:

 

I'm willing to bet the crank is toast. Its gouged pretty well. I don't think I'm even going to bother with a magnaflux, lol. I'll save that for one of my spares... This movement could very well explain the premature timing chain guide wear I posted in another thread in this section. Before someone says it, no, I'm not a clutch rider. I learned to put the box in neutral at every stop with my first car. The clutch that's in there now is a circular sprung RPS which isn't much stiffer than stock.

 

I'd like to thank everyone who convinced me to be anal retentive on this one. If I had just gone with a quick fix based on outside appearances, it could have ended a lot worse. Luckily, it looks like I'm down and out the previous parts mentioned, a set of Clevite bearings, and everything else I have spares of. I'll be getting the conrods checked too to make sure they're not bent. I know this stuff isn't groundbreaking or anything new, but I figured I'd document it anyway for people to look at. More pictures available upon request.

[garvice]

Check the small ends on your rods. In my case the rods actually stood up by themselves in the piston. Not the sort of resistance you want when you are running your engine at redline.

[Tony D]

Bummer on the thrust face...

 

I never start the car with the clutch depressed. Always in "N", same goes for sitting at a light. Clutch is either 'on' or 'off'...can't stand to sit there with the foot on the clutch, grinding away at the bearing thrust face...

[Oddmanout84]

Bummer on the thrust face...

 

I never start the car with the clutch depressed. Always in "N", same goes for sitting at a light. Clutch is either 'on' or 'off'...can't stand to sit there with the foot on the clutch, grinding away at the bearing thrust face...

 

 

I do the same. It bothers me to start my girlfriend's car because you're forced to depress it in order to start. I've actually yelled at her when I first noticed she was holding the clutch in while stopped in traffic. She doesn't do it anymore.

Edited May 27, 2010 by Oddmanout84

[Oddmanout84]

Check the small ends on your rods. In my case the rods actually stood up by themselves in the piston. Not the sort of resistance you want when you are running your engine at redline.

 

I still have further checks to do, but I guess I've essentially already tested this one when I put each piston/rod assembly on my bench. They're all flopping around nicely though not in any areas they shouldn't (that's I've seen thus far). I am worried about them being slightly bent though, with how much play was in the crank.

[garvice]

I still have further checks to do, but I guess I've essentially already tested this one when I put each piston/rod assembly on my bench. They're all flopping around nicely though not in any areas they shouldn't (that's I've seen thus far). I am worried about them being slightly bent though, with how much play was in the crank.

Sounds much better then mine, fingers crossed they aren't bent.

[Sideways]

I cringed a little when i saw the back of that thrust washer. That thing is a smidge more fubar than I thought. Straightaway From WME btw (Side note: My wme pun name will make sense now hah). Best of luck man. I have to admit I feel kind of bad in some odd way watching your project, Its like every time i took a step towards getting mine on the road, yours took a step back. Bad voodoo.

 

Get that thing back on the road asap!

[Oddmanout84]

I cringed a little when i saw the back of that thrust washer. That thing is a smidge more fubar than I thought. Straightaway From WME btw (Side note: My wme pun name will make sense now hah). Best of luck man. I have to admit I feel kind of bad in some odd way watching your project, Its like every time i took a step towards getting mine on the road, yours took a step back. Bad voodoo.

 

Get that thing back on the road asap!

 

Working on it! Waiting on parts, then waiting on machining, then I get to put humpty dumpty back together again. In the meantime I'm improving other areas that would otherwise keep the car from moving (possible 240sx transmission swap, cleaning up ALL the engine bay wiring). The only thing I'm missing is a welder, otherwise I'd be fabricating a Ron Tyler diff mount and fixing my fenders under the flares. May remedy that this weekend.

[Tony D]

I do the same. It bothers me to start my girlfriend's car because you're forced to depress it in order to start. I've actually yelled at her when I first noticed she was holding the clutch in while stopped in traffic. She doesn't do it anymore.

 

One of the first things I did to the Y2K Frontier my wife has was to disconnect that damnable clutch switch. Yes, I can start the car in gear now. I still believe I have enough intelligence to remember to shift to 'n' before starting the car. I also have anough honor to understand if I run into my own house because of a temporary lapse of reason, it's my problem, and not Nissan's....

 

I hate those switches. Same goes for shift interlocks on Automatics.

 

I could go on and on...

 

Anybody remember when you had to adjust lubrication rate and pump the crankcase full of oil on your motorcycle? Manual Rocker Arm Lubricators?

[kj280z]

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.

 

Also, when pushing L Motors to limits a BHJ damper is the way to go.... they are expensive but well worth it - I had cronic problems breaking dampers in my turbo and supercharged setups - switched to a BHJ and the problem was solved. - I have one for sale in the classifieds

[Oddmanout84]

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.

 

Digging up old dirt...

 

Nearly a year later, I'm just about ready to put everything back together. Block has been machined and freshened up, I got a different crank, entire rotating assembly rebalanced. I also had ordered a new damper and bolt/washer around the time of Tim's post. Its the damper from MSA, along with the Nissan comp bolt/washer. That being said with it bottoming out on the crank snout too soon, is there any way to remedy this besides machining? Perhaps a very thin, circular, washer-esqe shim? I have not test fit the bolt yet to see if it indeed bottoms out too soon, but I'd hate to have it on there and replicate last year's debacle within the span of the next year.