The bolt/nut that holds the crank shaft pulley on has loosened up on me several times. This is problematic as 2 pulleys end up hitting and stopping the belt from turning. The 1st time it caused 2k in damage. The 2nd $500. Now I don't know if I should bother repairing it.
The last time, I had it torqued it and added 5000 lb epoxy and it still loosened. If anybody has any advice on how to hold it in place it would be much appreciated?

Stock pulley? Any particular model/yr/engine?

Sorry. 1990 350 sdl. Stock pulley to my knowledge with 324k on it. I purchased the car about 18 months ago and after a belt tensioner broke, the crank shaft pulley became loose.
Diesel 6cyl.

My local mechanic had torqued it..to what degree, I'm not sure.

Any advise?

If the shaft is damaged and or pulley worn inside the bolt won't hold it. Measure the fit. Inside of the pulley and shaft end. Should be .001-.002 " or so clearance. If you have more than that it won't stay on because the space will cause a small amount of wobble which will eventually lead to the problem. If the pulley is worn use a new one. You never stated a new one was installed. Using a new one might help if the crankshaft isn't damaged severly.

Very good info by vettdvr, the longer you leave it the worse it will get, if the key way is damaged thats the end of it

yep the key was damaged and the end of the shaft shaved.....its over

Sorry..

If the shaft is still relatively fair shape but key way damaged, you still might get away with a new pulley. But if the shaft is scored it is over and the only solution is to pull the engine replace the crank and pulley. Basically a new engine.


A final attempt to never be removed would be new pully and Locktite. This would be permenant and if it stayed the crank would be totalled for sure. If the engine is on it's final legs and you are trying to nurse a year or so out of it for local driving you might try it. But remember all the belts pull on this and any play will transmit to the bolt and you go back to square one new engine. Sorry. That's just the way "the shaft fits"

thanks again. I am told by my mechanic that I would also need a new flange. It's too much to buy from MB. Would you know where I may locate a cheap one?
part # 6030300303