Did I strip it! (Please comfort me in my time of need)

[ENDLIFE]

Today I was wrapping up my vibration elimination job. While I was underneath the rig looking to see if the new flexplate counter weight would clear, rotating the engine with the damper bolt, and then to my absolute horror the damper bolt got really easy to turn. I'm mortified that I may have stripped it! I talked to a friend about the potential issue, he said that it was highly unlikely that I stripped the crank hole, and the damper probably wasn't seated all the way.

Has this happened to anyone else?

 

[hogfan]

Did it ever get tight?

 

[DJs74]

Hard to say without a little more information. Did you try removing the bolt to take a look at the threads?


DJs74

 

[jrwyant]

I find it difficult to believe that you could strip that meaty bolt by simply using it to rotate the crankshaft... if that did strip it, then something else was wrong, and you found it ahead of it appearing far away from home at the worst possible moment.

So I agree that the dampener probably wasn't fully seated to begin with. (But I also agree that you could remove the bolt, study its threads as well as those in the crankshaft, to eliminate the worry.)

Did you install the dampener yourself? (And did you torque it to specs.?)

 

[ENDLIFE]

I installed it after I machined and rebuilt the engine. I'm obsessed with spec torque. I did notice that when I turned the crank the bolt would tighten a little more and more, but I didn't try to retorque it after it went grotesquely loose. I didn't see any sheered threads on the bolt, so I thought maybe they came off in the hole. I am a whooping boy for Murphy's Law, so I thought I would consult one of the most awesome communities I know.

 

[pcf_mark]

I hope you did not strip it and what you did surely should not have.

But i will say if the crank bolt is too long and it bottoms before the balancer is seated the torque will pull the threads out. Also if you are lucky the bolt gave up and not the crank threads. Even you do have a problem and the bolt was short you may have more good threads further down.

If you are total hosed and the crank stripped you can tap it oversize in the truck.

 

[jckkys]

I looked through my huge bolt bucket and found 3 crank snout bolts to see if some are longer but they're all 1 5/8". Most Ford V8s use the same one. The exception is the 351C. I would pull the vibration damper, and put the bolt in with grease on the threads and see how deep it goes and how easy it turns. A thread chasing tap would clean up the threaded hole in the crank. The junk yards are full of Ford bolts for V8s too. Other engine families use the same bolt. ARP has these;http://www.jegs.com/p/ARP/ARP-Harmo...0&Ntk=productgroup&productId=744916&Tab=SKU&e replacement bolts that are over 2" long. The thread pitch is 5/8"18.

 

[DirtDonk]

Exactly that.
My first thought was that even if you'd taken the bolt out yourself and put it back in the last time, it's still possible that someone in the engine's past put a slightly too-small bolt in the hole and it tightened up just enough to function.
That seems pretty unlikely, as it would probably just not fit at all. But you never know...

Good luck.

Paul

 

[Rustytruck]

5/8-18 with an inch of thread in the crank should break the bolt before you strip it. Only way to know is take out the bolt. If the bolt looks good check the bolt threads for distortion right at the end of the crank snout. Any sign if stretch or twist replace the bolt. Now if the wrong bolt was used and too short then you may have problems.

 

[langester]

Is it possible the damper was not totally seated and you pushed it on the final bit and loosened the bolt? Just a thought? Good luck man!

 

[73azbronco]

remove bolt and check.

 

[blubuckaroo]

I just looked up the torque spec for that bolt in my Chiltons manual. They give two different torque specs. 66'-91' is 70-90 ft lbs, but has a note that '74-'77 is only 35-50 ft lbs.
I found that a little strange, but I have actually had one break while in service. It sure wasn't fun trying to get the broken bolt out. I was told later by a Ford mechanic that the 35- 50 ft lbs was correct for my car and I had over tightened it. That's very possible since those torque specs are for dry threads, and I had used antisieze.

 

[BruceAH]

Post (above) re: the not-fully-seated damper was my first guess too.

 

[ENDLIFE]

Thank you all for the comfort in my time of need, and I pretty sure that my damper was not seated all the way. The only thing I can think of is the installer that I used must not have pushed it all the way down, and maybe some gunk caused the damper bolt to torque to the required spec. I'm super relieved that I only had one major problem instead of two. For those of you that are fighting a vibration problem, SFI heavy duty flexplates SUCK and made my rig a vibrating beast. My 5.0 is running smooth, and I don't have to worry about the damper flying through the hood.

 

[73azbronco]

Those need to be balanced with the rotating mass while off the engine.

 

[September 1972]

Did you use a new bolt made in china?

 

[jagbucket]

so you never took it off to inspect ? and are just running it as is not to torque spec ? this will not end well if that is the case. at the very lest it will ruin the key way in time