I posted this in another thread a few months ago, but I have an '04 Tahoe w/183,000 miles. The same tick came up out of nowhere, and my wrench nephew told me to add two qts of ATF to the engine, on top of the oil without draining any off. Idle for 10-15 minutes, no rev, no drive. Change oil and filter w/o any ATF, back to normal.
I ended up with 1 qt of Gunk engine flush and 1 qt of ATF to do the deed and all is good. I'm just about to do the next oil change at 3,000 miles and just for the hell of it, I'm doing the flush again. The Tahoe has been running as it should since the engine flush...nice and quiet.
Cheap and easy DIY possible fix. Worked for me. Good luck...
Jamo
