Bellhousing noise and sluggish

[2013 nick]

Hi guys- I have a 2013 Sierra 5.3 with 127000 miles.  I’ve owed since new.  A tick or chirp noise started coming from the bell housing 5 days ago.  At the same time I noticed drivability problems.  The noise is fairly faint, always there unless accelerating in reverse, and inconsistent (no pattern to it).  It gets faster and slightly louder with engine speed. I had thought it was a cracked flex plate, but that doesn’t explain the drivability issue. It bogs down really bad or lacks power starting from a stop.  Sometimes it’s really bad, other times you might not notice if it wasn’t your truck.  Possibly worse when hot, but so inconsistent it’s hard to say.  Any ideas?  Torque converter?  Trans fluid is clean and full. Thanks for any thoughts!

Edited July 4, 2020 by 2013 nick

[davester]

How did you narrow it down to the bell housing and not the engine or transmission?

[2013 nick]

Hi davester- I used a stethoscope.  It also got noticeably louder when I took the little cap out of the bottom of the bell housing.  Listening to the oil pan and tranny pan, both sound fine.  The cats both sound fine as well.  I also pulled the o2 before each cat because it sort of acts like a plugged cat, but it still acted sluggish even with both sensors pulled.  Plus it seems fine at higher rpm and higher gears.  Also ran without the SERP to eliminate those noises

[davester]

That sounds like you did a great job of narrowing down where the problem is.

 

Sorry, I don't have the experience to directly help with this problem, only thing I can suggest is to get a subscription to the full-service manual for your truck and go through the transmission diagnosis section (the torque converter stuff would be there).

[2013 nick]

Where do I go for a subscription to the full service manual?  I bought a chilton manual, it was helpful, but not as detailed As it sounds like this subscription would be

[txab]

One place is http://www.alldatadiy.com/index.html

[2013 nick]

Hi all- sorry I forgot to post a reply until now.  I wound up pulling my transmission and replacing the torque converter and flex plate.  After getting it all back together the noise and drivability issue were both still there...  I finally took it to a transmission shop expecting the worst.  It turned out that my starter was broken and causing the clicking noise I heard as the starter gear was bouncing off the flex plate.  The noise or vibration was causing the knock sensor to pull power away from the engine, causing my drivability issue.  Very glad I lucked out to find a transmission shop that Figured this out.  My brother is a GM tech for almost 20 years.  He has never heard of something like this, nor had anybody in his shop.  It’s now almost 3 months later and no more problems

[davester]

good stuff. thanks for coming back and posting what the problem/fix was.