93 MTX - Busted timing sprocket

[notahemi72]

I've got a broken crank key and timing belt sprocket. From what I've read, I probably caused it by undertorquing the crank bolt a few years ago. I fought the crank pulley removing it and before I do anything with the busted key and timing sprocket I'd like to get some adivce on how to proceed to minimize the damage. Not sure if the attached image is clear enough, but does it look like I can salvage the crank and get away with just a new key and sprocket? Where can I get a key and sprocket. 290,000 miles - I want to keep it on the road. Thanks.

View attachment 1344

 

[intimdatr]

How bad is the crank slot for the Key?
This is called crank cancer around here, and cancer as you know is not a good thing that doesnt really have a cure.
You need to pull the sprocket off and find out how bad the damage is.


Edit: and the more i look at the pic the worse its looking.

 

[Irish Pride]

If the damage is to the Key and Sprocket only then you can replace them and be good to go. If the keyway is damaged which i'm thinking might be the case looking at that pic then you would need to replace the Crankshaft too. A new Key can be had at SHOsource and a sprocket can be pulled at any junk yard.

 

[notahemi72]

Thanks for the replies. I ordered a key and sprocket from SHOSource. I'll let you know how it goes. About 9 months ago I drove through about a foot of standing water from a Texas spring storm. There was a lot of rust on the crankshaft as I removed the harmonic balancer.

 

[jimtash]

It's easier to remove the crank bolt than it is to torque it down. Good luck with it.

 

[notahemi72]

The SHO is back on the road with new key, sprocket, cam and crank seals, belt, tensioner pulley, and cps. Here's a picture of the wallowed keyway. I coated the keyway, crank and inside of the timing sprocket with Loctite 660. I planned to get the damper on and the crank bolt torqued before the 660 set up, but it set up in about 5 minutes. I used Loctite 242 on the damper and crank bolt. 145 ft-lb on the crank bolt and let it sit for two days. I've got a day on it so far.

View attachment 1358

 

[3d914]

How bad is the crank slot for the Key?
This is called crank cancer around here, and cancer as you know is not a good thing that doesnt really have a cure.
You need to pull the sprocket off and find out how bad the damage is.


Edit: and the more i look at the pic the worse its looking.

Looking at the way the keyway is hogged out along the back end - couldn't that portion be welded and remachined to clean it up? Seems like the waste of an otherwise good crank.

 

[Off Road SHO]

Looking at the way the keyway is hogged out along the back end - couldn't that portion be welded and remachined to clean it up? Seems like the waste of an otherwise good crank.

Yeah, but to do that the right way, you would have to remove the crank and take it to a machine shop that turns cranks for a living. And it would be in the hundreds easily.

Tom

 

[notahemi72]

Update - 100k miles later the Loctite 660 is still bonding the crank sprocket to the crank. Last year I removed the pulley and replaced the crank position sensor without touching the sprocket. The SHO is going strong at 371k miles.

 

[Irish Pride]

That's awesome!