The nut for the crankshaft pulley keeps coming loose , I have tighten it with a wrench , but keeps loosening , the motor is new with only 400 miles , is this normal or is there a permanent fix .
Original Post
Replies sorted oldest to newest
Loc Title it and be sure you have the correct torque
Here's a good link to torque settings - it calls for 33 ft/lbs
https://www.hotvws.com/content.php?contentID=62
If this is an aftermarket crank pulley bolt, check the length vs depth of threads in the crank. Years ago I had a SPG roller crankshaft, and the 1 1/2" oversize gland nut was slightly too long and was bottoming out. I thought the crank was tight, but after it came loose twice, with loctite, I investigated further. I wound up machining a couple of threads off the gland nut, problem solved.
Thanks for the info I torque the bolt and put loc tite as suggested hopefully this does it , I do not know anything about it being after market like I said the motor is new , the car was built by Greg from Vintage , so that is all I know about the engine .It says Brazil on it so I guess it is from Brazil.
As Rick said, measure the depth of the threads in the crank (and not just the depth of the "hole") and compare to the length of the bolt to make sure the bolt isn't bottoming out and preventing itself from being torqued properly. Although the case has Brazil cast into it, the engine was probably assembled by someone stateside and will be a a collection of parts (and not factory assembled in Brazil), hence the reason these things have to be checked.
Hope this helps. Al
Sometimes the pulley and/or the woodruff key(is one in there?) can be a loose fit and cause the loosening. The pulley can be out of balance or out of round which causes vibration and loosening also.
Since the engine is in the car, tightening the pulley bolt properly can be difficult. On an engine stand or off, using a flywheel lock makes it easy.
In the car, you put it in first with the brake on, but that may not be enough to trque the bolt properly. Put a big screwdriver(square shank, not round) or prybar behind the alternator pulley and squeeze the belt together to prevent slip. You squeeze the belt together with a couple ty-raps. Then you should be able to tighten the bolt. You should not need loctite, in fact I recommend against it.
Precision-machined billet steel pulleys(Gene Berg and JayCee for example) use a much higher torque value than a stock pulley. I'd make sure everything is clean and tight and straight, and that the threads on the bolt are neither too short or too long, and torque to 43 ft. lbs.