Buggered Crank Threads....

[stonesg]

So I'm replacing the timing cover gaskets on a 2001 Taurus (they leak... It's a thing..) and I think I buggered the first few threads where the harmonic balancer mounts.

I usually clean all fasteners and test them and this one seems to be trying to cross thread and gets hung up.

The bolt's threads look good.

I think I used the wrong center on the puller and may have mashed the first few threads.

It's a 14X1.5 thread and I was thinking that using a tapered tap I could get it started and clean up the messed up section.

Am I on the right track? I'm going to go look for it a tap tomorrow as my metric set tops out at 12.

TG

 

[Wamsutta]

You're in better shape than I am. I tried to ram a M8X1.25 tap through a cylinder head that had 5/16-18 threads. Now I have to scrap the cylinder head. Everything on the car is metric right? Wrong!

 

[chrisnazzy]

I'm thinking you'll want to start with a rethreading tap in lieu of an actual tap. I'm not claiming to be an expert here but the way I understand it, a standard tap is designed to cut threads while a rethreading tap is designed to clean up threads.

I have a rethreading set that I've used many times with success. Snap-on, Matco, Mac and even Craftsman all have a set and I'm pretty sure all are rebranded Irwin/Hanson or Kastar/Lang. They all seem to be around 48pc. and include metric and SAE rethreading taps and dies and most also come with thread files. These kits are also called thread restorer kits.

Here is a pic of mine. It does have 14mmx1.50.

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[yhprum]

You need a back tap like this one. It collapses to get past the buggered thread, then the mandrel expands it and you unthread the tool, cleaning the threads on the way out.

https://www.amazon.com/dp/B0014FGVVW/?tag=atomicindus08-20

 

[454ragtop]

Might be able to use a grinding wheel in a die grinder to grind away the first couple threads, won't miss 'em.

Wamsutta, can you use a Heli coil to fix the head, or substitute an 8MM bolt?

 

[Honda guy]

You need a back tap like this one. It collapses to get past the buggered thread, then the mandrel expands it and you unthread the tool, cleaning the threads on the way out.

https://www.amazon.com/dp/B0014FGVVW/?tag=atomicindus08-20

Agreed.

 

[unslow1]

You need a back tap like this one. It collapses to get past the buggered thread, then the mandrel expands it and you unthread the tool, cleaning the threads on the way out.

https://www.amazon.com/dp/B0014FGVVW/?tag=atomicindus08-20

That was my first thought also.

 

[619DioFan]

I'm thinking you'll want to start with a rethreading tap in lieu of an actual tap. I'm not claiming to be an expert here but the way I understand it, a standard tap is designed to cut threads while a rethreading tap is designed to clean up threads.

I have a rethreading set that I've used many times with success. Snap-on, Matco, Mac and even Craftsman all have a set and I'm pretty sure all are rebranded Irwin/Hanson or Kastar/Lang. They all seem to be around 48pc. and include metric and SAE rethreading taps and dies and most also come with thread files. These kits are also called thread restorer kits.

Here is a pic of mine. It does have 14mmx1.50.

Sent from my SM-G930P using Tapatalk

I have that set and it has saved my **** many times.

 

[BillK]

I have never used anything other than a plain tap. You are just trying to clean up a few threads, not the entire hole. Dont make it more complicated than it really is.

 

[tatra]

I have used backtaps on sparkplug holes after others tried to clean them up using a conventional tap . Honestly the best investment I ever made on a rarely used tool . I just never knew the name of them . If your size is available, I would wait until I got one . Cranksnout threads aren’t an item I would chance . Best of luck .

 

[Mr_B]

On well damaged starting threads a ordinary tap likely best way start besides the back threading tool .
I done loads over years with ordinary tap to start then a thread cleaner if got one .
Need visual check see how bad it is and that tap likely work in on original thread path as feeding it in .

 

[Schurkey]

If it's like my old GM engines, take the damper bolt out, remove bigass washer. PUT THE BOLT BACK IN as far as it will thread, before installing puller tool. Puller center bolt pushes on bolt head, not directly on crankshaft. Cannot screw-up crank threads.

 

[ScottsGT]

Hope you can fix it. Sons friend was swapping balancer on his 2010 Mustang GT in my driveway. Instructions were very clear on how to start tightening down with the longer bolt provided, then switch over to the stock bolt to pull it all the way in.
He started the install and got distracted and asked my son to finish it, he never read the instructions.
Car was towed off to the shop and a new crankshaft was installed.

 

[BuffettFan]

You're in better shape than I am. I tried to ram a M8X1.25 tap through a cylinder head that had 5/16-18 threads. Now I have to scrap the cylinder head. Everything on the car is metric right? Wrong!

Can you helicoil the threads, or another type of thread insert? Way cheaper than a new head and depending on where the they are, probably wouldn't even have to remove the head.

 

[stonesg]

Man I knew the GJ brain trust would come through...

A back tap seems like a good genius idea but all the 14mm ones I can find avaliable appear to be for spark plug threads which is 1.25 pitch.

I'm going to see if I can find a chaser or set and a tap on the way home today.

I cannot see anything but little dent on it left side in the this image so it's not going to take much.

 

[Packard V8]

Yes, No, Maybe, BTDT. I just had to buy a Chicom three-piece carbon steel set 7/16" x 20 tap set to clean the snout threads on a Studebaker V8 crankshaft the owner had buggered in that same manner.

The set was amazingly cheap; like $7.08. I'd never buy those to actually cut new threads, but for a one-time clean-up use, they were perfect. Starting tap to clean the threads and then a bottoming tap to make sure the threads were straight all the way down.

jack vines

 

[GrayFlattop]

I've used a thread chaser / restoring tool like this with good success. Not sure where I got it (McMaster Carr?), but it remains an alternative to the back tap.

 

[stonesg]

We'll it appears that in the backwater that is Richmond Virginia that a 14X1.5 tap is unubtainium. Mostly because our biggest local tool supplier is closed through Monday for the holiday.

Even Grainger couldn't get me one till next week.

McMaster was an option but I cheaped out thus...

Amazon to the rescue and a taper/plug set is inbound.

I'll report if there's any carnage.

TG

 

[ricleh]

Internal thread restorer

 

[stonesg]

Success Gentlemen.

The tap magically showed up in my driveway this morning and after gingerly getting it started, it cut for about one turn and then started threading in like a bolt.

It was a little tough to make sure it was running true as the engine is still in the car so I'm on the ground holding the inner fender out of the way while trying to eyeball the tap. It also tried to start crossed up just like the bolt but by keeping it straight it finally did the trick.

Thanks for the vertual look over the shoulder.

TG

 

[Mohawk Dave]

Since it's the first threads, look at NES rethreading tools.

 

[6PTsocket]

Irwin/Hansen makes the cutting taps and dies. Lang, formerly Kastar makes the rethreading taps snd dies for almost everyone. I agree that a retheading tap is the way to go. You want to straighten the threads, not cut them away. You can loose a lot of thread with a cutting tap if you are not careful.

I'm thinking you'll want to start with a rethreading tap in lieu of an actual tap. I'm not claiming to be an expert here but the way I understand it, a standard tap is designed to cut threads while a rethreading tap is designed to clean up threads.

I have a rethreading set that I've used many times with success. Snap-on, Matco, Mac and even Craftsman all have a set and I'm pretty sure all are rebranded Irwin/Hanson or Kastar/Lang. They all seem to be around 48pc. and include metric and SAE rethreading taps and dies and most also come with thread files. These kits are also called thread restorer kits.

Here is a pic of mine. It does have 14mmx1.50.

Sent from my SM-G930P using Tapatalk

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