Tackling 2 leaks, rad and front main

[rcb280z]

I did think that yesterday but I've owned this car since 1985, the harmonic balancer was off twice and the same key went back in. The last time the balancer was off was in 1995. Replaced it with a used one because it was separating. Been on there ever since, with the same key.

Edited March 4, 2018 by rcb280z

[rcb280z]

Picked up the aluminum radiator today. Here's a pic of the repair. Note the epoxy. They did all four corners. Said to make sure I have it grounded properly.

[ensys]

Mr.rcb280z:

First, the Woodruff key has a round bottom to fit into the only slot (round bottom) that can be machined into a crank (ever see a rotary tool that cuts a square-bottomed slot?). When assembled at the Factory, a key that was carefully machined to be tight, was snugly fitted into the slot. This is why every description of its removal demonstrates the need for force and finesse.

If you're lucky, you'll find that the new key cannot be fitted properly without removing the front cover. If not, even the correct key will drop in easily. If it does, it means that the once parallel sides of the slot are now not, as one or both have become sloped, assuring further problems in the future.

Theoretically, the key should never have come out easily in the last two operations in the first place. Perhaps the failed balancer pulley induced unusual stress on the key, causing enough wear on the pulley slot to hammer the key regularly. Again theoretically, the key should absorb the wear, as they are typically a touch softer than the crank they are fitted to.

So, harsh as it sounds, I hope you will be cursing the need to pull that cover; the alternatives to anything more than a kiss-and-a-promise repair get ugly fast.

Good luck.

[Captain Obvious]

20 hours ago, ensys said:

the only slot (round bottom) that can be machined into a crank (ever see a rotary tool that cuts a square-bottomed slot?).

End mill. You cut on the tip instead of the side. Poof. Flat bottom slot.

Then you use a flat bottom key instead of Woodruff. Plenty of auto manufacturers do it. 

[Zed Head]

Just feeling a chime in urge.  These keys are generally meant for location purposes only, or mainly.  The clamping force of the bolt is what stops the movement.  105 foot-lbs, etc.  If a person really wanted to be detail-oriented, they'd clean the surfaces that clamp together to ensure high friction and metal to metal contact.  The key probably needs to be strong enough to resist the torque transmitted through the bolt head in to the damper.  You can sit and imagine where the loads go, if you want to, and figure out what to clean and what to lubricate.  Lots of surfaces involved.  Lubricate under the bolt head and washer, clean the space between the damper and crankshaft.  Choose the right oil for the threads.  Say a prayer...

 

[ensys]

 

Mr.Cpt.Obvious:

I would note that you can't have it both ways; its either round bottom or round ends (now wouldn't that be an interesting "key" to machine with precision... imagine trying to extract that puppy at Factory fit specs).

Mr.ZedHead:

And when that end bolt either loses its clamp or the pulley develops sufficient eccentricity in rotation so as to develop tangenal rotational stresses... Well, I believe Mr.rcb280z has graphic evidence of the peril.

There is a reason, beyond a passion for precision, that mfgrs. provide such close tolerances in any keyed assembly. It is the last line of defense for rotational continuity.

Of course, splines (longitudinal or radial) would do the best job of rotational lock, but they are soo expensive to cut en masse, as opposed to a simple keyway cut. If it was just a matter of locaton, dimples/scribe marks in the parts, or perhaps a shallow longitudinal kerf and inside spur, would do the trick.

Edited March 5, 2018 by ensys

[Zed Head]

I think it's a matter of scale.  If you're transmitting small loads then a key, a small tab of metal pushing on a small area of the shaft's outer perimeter, is probably fine.  The damper pulley transmits a lot of torque though.  And the are of the damper with the slot in it is thin and fragile, hence the breakage.  Seems to be more for location.

I over-generalized to all keys.  I do remember plastic extrusion applications where the key was used as the failure mechanism, to save the shaft and other parts from over-torquing.  So it was the power transmitter in that case.

 

I searched the internet and have supplied only the words that kind of support my argument, below.

https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/Key_(engineering).html

[Mark Maras]

Briggs & Stratton engines used an aluminum flywheel key as a "failure mechanism." The keys were often offset after years of use.

[rcb280z]

**UPDATE**

Finally got everything in. Installed the balancer. Wanted that out of the way. The woodruff key fit snug, not loose or too tight. So I'm certain of no keyway damage. 

Now I just need to put the rest of her together.

 

[Captain Obvious]

Excellent. Just another example of a fifteen minute job turning into a two week long expensive ordeal.

We've all been there, done that!  

[rcb280z]

Just finished putting her all back together. All looks good. No more leaky radiator or front main seal. I'll probably check more times than I'll need to but I guess you can't be too careful. I still have 2 more leaks to tend to. Looks like rear main is leaking, maybe. Also looks like the pan gasket is leaking after all. You would think I was loosing a lot of oil with these leaks but I never have to top it off. Thanks to everyone that helped me with this last repair.  

[esmit208]

I for ONE am glad you took the time and did the work. Above all it sharpens your trouble shooting skills and ability to tackle a somewhat complicated procedure. Next..... building the TC24B-1Z! Nice work!