I just recently changed my timing chain tensioner because of a rattle on cold starts (the guide was not broken, so I'm hopeful it was a bad tensioner.While I was at it, I thought it would also be a good idea to replace the water pump since I had everything apart.
Here are the steps I took so far...
1) Rotate the engine clock-wise to set top dead center for good measure (I'm not 100% sure I did this right, but I matched the crank pulley single line to the the water pump pointer)
2) Removed the old timing tensioner
3) Rotated the engine counter clock-wise for slack in the water pump (Service Manual says 20 degrees, but I was paranoid of having the teeth skip so I probably got it to work at 17-20 because it was a little tight)
4) Replace waterpump and then installed new timing tensioner with pin intact. Tighten down all bolts
5) Rotate engine clock-wise to remove slack and then remove new tensioner stop pin.
At this point I felt confident and decided to manually rotate the engine a few times clock-wise to review mechanical, but I'm concerned about something! I noticed every rotation or so, the tensioner would compress and then complete decompress!! Is this normal behaviour for air being in the system? Also I do have my spark plugs removed because I am changing them as well. Is this what's causing the tensioner to decompress?
I'm scared to death to finish putting everything back together only to start my truck and I'm fearing the worst. Anything I can check besides pulling the timing chain cover and oil pan off to review everything. I'm really concerned about the tensioner decompressing and then compressing after every rotation. Just not sure if this is normal considering I just replaced it and there wasn't spark plugs. Just wanted to get some opinions before I try to finish the job.
I appreciate any advice before I continue on. By the way, my truck is a 2001 QX4