Nismo280zEd Posted July 22, 2005 Share Posted July 22, 2005 Ok... about the last month my crank pulley keeps coming loose and I can't figure out why. My belt is fine, nice and tight. I've torqued the bolt back down several times to only find it loose a couple days or weeks later. The last time I put thread lock on it with no availe any ideas why it's coming loose all of a sudden? I never run past stock redline. -Ed Quote Link to comment Share on other sites More sharing options...
TheNeedForZ Posted July 22, 2005 Share Posted July 22, 2005 Is it dirty inside the threads? Maybe you could clean it or chase it with a tap. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted July 22, 2005 Author Share Posted July 22, 2005 Nope, the threads are clean.. I checked that when I put thread lock on it. Only thing I can think of is one of my pulleys being bent somehow. -Ed Quote Link to comment Share on other sites More sharing options...
260DET Posted July 22, 2005 Share Posted July 22, 2005 Hate to say this but the hub may be loose on the crankshaft ie the fit of the pulley on the crankshaft may not be tight enough. Loctite both may help in the short term. Quote Link to comment Share on other sites More sharing options...
srgunz Posted July 22, 2005 Share Posted July 22, 2005 Once the key and keyway get hammered for a while it will no longer stay tight. Check it close. If so you will need new pulley and key. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted July 22, 2005 Share Posted July 22, 2005 Both of the last two suggestions are correct. Once the pulley gets loose it wobbles on the end of the crank, which makes the fit looser and then it won't stay tight. Usually also breaks the slot that the woodruff key sits in. Some loctite in there might make it last a while. One engine I took apart had loctite in there and was running fine for a long time by all appearances. I actually scrapped a motor because of this. I didn't notice the pulley was loose until way too late, and then when I got it off the end of the crank was just screwed. The rest of the motor was fine, but I ended up building another shortblock. On my engine the rubber in the pulley had come apart. Never figured out if the rubber went because the pulley came loose or the pulley came loose because the rubber went. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted July 23, 2005 Share Posted July 23, 2005 I remedied the "loose crank pulley" problem with a slightly longer bolt from a bolt and thread shop on a previous motor.... Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted July 23, 2005 Author Share Posted July 23, 2005 I've already replaced the pulley and the key once on this motor because the rubber in the harmonic balancer was shot and throwing it off balance, but this pully doesn't even have 2k miles on it! I'll check the key and see if it's worn at all today. Thanx for the suggestions -Ed Quote Link to comment Share on other sites More sharing options...
heavy85 Posted July 24, 2005 Share Posted July 24, 2005 There are several different grades of loctite - may want to try the 'permanent' stuff. There is also a loctite made for slip fit application like the pulley on the end of the crank which is different than the threadlocker and may work better? I used to work with someone who used to work for loctite and I would hear stories. Apparently back in the early days the salesmen used to drink some for show since it's anerobic (cures in a lack of oxygen) and the body's got plenty of oxygen so it wasn't really that harmful. Also used to hear the stories when he worked the helpline ... like my grandson superglued my a$$ to the toilet seat and I cant get up kind of stuff. Cameron Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted July 26, 2005 Author Share Posted July 26, 2005 actually I took the pulley off the other day.. the key was about half worn threw.. about to shear. So I replaced it with a nissan spec key from a spare motor I have... no play anymore and I feel confident that fixed the problem. -Ed Quote Link to comment Share on other sites More sharing options...
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