So the timing belt was done on my car and all the marks are lined up and the belts are lined up perfectly but after 10-15mins of the car just sitting there the intake gear would turn clockwise and loosen the timing belt. Anyone know what would cause this?

Depends on how much it moves. A little is typical, but anything more than a few degrees is likely tensioned incorrectly.

I would say it moves like 3 degrees or so.

Did you replace the tensioner also?

you have a broken tensioner... saw it before... you should have changed the tensioner at the same time..

The tensioner was changed at the time of the install of the timing belt. I changed another tensioner and it seems to fixed now. Will have to monitor for a while and hopefully that will solve my issue.

I was kinda battling this issue as well. The tensioner pully has the 2 holes for the special tool to apply the 31 in. Lb. As you tighten that 14mm bolt down. Make sure you apply 31in lb of presure in the counter clock wise direction. When applied clockwise direction thats when it got loose after 5-15 min but all marks do line up and the belt gets tension properly when you turn the crank by hand. Hope this helps.

Sorry to thread jack but, when I torque the 14mm bolt down to 36 ft-lbs, the pulley arm moves and the belt comes loose. The tension also becomes incorrect and the grenade pin on the auto tensioner does not easily moves in and out. Anyone got any tips for torqueing this bolt down to 36 ft-lbs without getting the tension on the pulley messed up? Thanks in advance.

You have to hold the pulley with the 31in lb as you tighten that 14mm bolt to 36ft lb. Jays racing timing belt kit also got that bolt which holds the tensioner arm in place. Good luck hope this helps you.

If you don't have a specific tool just use 2 small Allen keys. Actually that is all I have ever used.