Crank Threads on Deere 466 engine

Anonymous-0 · Aug 12, 2008

I've stripped the threads in the crank for the bolt that holds the harmonic balancer on. I think there is enough depth to the hole to retap, but the crank is probably heat treated and not having any luck re-threading. Sure don't want to snap the tap off trying. And a d**n hard place to get into.

Any history of this on this (or sim) engine? Any known fixes?

bison · Aug 12, 2008

there are taps avalable to tap hardened or difficult materials.For next size tap you prob need to drill hole bigger too.Take a file to the edge of the crankstub,if it files it can be tapped.As last resort if all else fails,you could run a stud in the bore and weld it to the stub,only problem is that if the crank needs to be ground in the future,the taper in the stub is used to center the crank in the lathe.

Bob · Aug 12, 2008

IMHO, you would be better of using a Helicoil, rather than making the hole "deeper", or a lot bigger.

jose bagge · Aug 12, 2008

Hate to admit that I've done this before but...oh well: put the harmonic balance on and shoot 4 little tacks every 90 degrees with Mig. it will hold it on just fine, and if you need to remove it in the future just grind the tacks away with a dremel.
I actually RACED a SBC held together this way, and i have about 20,000 miles on a Geo tracker with the Cam gear key tacked into the snout of the crank (gear came loose and wobbled out the key slot). I KNOW IT AIN'T RIGHT, but it will git r' done...

Bob · Aug 12, 2008

With the reputation these engines have for tearing up dampers, I wouldn't even consider that!

Anonymous-0 · Aug 12, 2008

Not aware it was a problem with these engines. Does Deere or anyone offer an improved balancer? I'm probably not going to get a second chance to save the crank, so I need to fix it best I can this time.

buickanddeere · Aug 12, 2008

The stud idea is probably best.
Run a bottoming tap in the threads to get the stud in as deep as possible and into the best threads at the bottom.
Slobber some thread locker in there and away you go.

Bob · Aug 12, 2008

There's a recommendation to change the balancer after a certain amount of hours (crs at the moment).

I have personally seen a number of them fail and go "off center" to the point the tractor jiggles up and down on it's front tires at idle.

On one of those, the crank snout was cracked by the time the customer had us look at the balancer.

rexhellwig · Aug 12, 2008

Ahem..

These threads don't just "strip out". Were you trying to pull the dampener back into position using the originl bolt? This is a no-no. You need to start with a longer 5/8 bolt and pull it home part way, then finish with a new original bolt.

If this is what caused it, you probably didn't damage more than two or three threads. There is usually room in the crank snout threads for a "custom" bolt a 1/4 inch longer. If it ends up one or two threads too long, grind the longer bolt off. If you still have twelve good threads in the crank, that's plenty.

If for any reason, the dampener has run loose on the crank, {even for a short time} forget about counting threads. you're going to need another crank and start over.

Crank Threads on Deere 466 engine

Anonymous-0

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bison

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Bob

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jose bagge

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Bob

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Anonymous-0

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buickanddeere

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Bob

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rexhellwig

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