billschall
04-19-2007, 11:04
A knocking sound presented itself about a week ago. From inside the cab, it sounds like the handle of a screwdriver being smacked against an aluminum housing that's full of oil. It's neither a hollow sound nor does it appear to be a solid sound. Here are the interesting variables:
(1) The sound is absent when everything's cold.
(2) The sound is absent if I let the engine warm up to operating temp but do not drive it anywhere.
(3) The sound is present after driving about five miles.
(4) The sound runs concurrent with engine RPM
So, I'm thinking tranny. It's a 4L80E.
Last night I crawled underneath with my screwdriver/stethoscope and auscultated various locations.
(1) The sound is almost absent in the engine oil pan.
(2) The sound is very prominent around the TC housing cover.
(3) There is also a noticeable "clicking" noise inside the tranny pan.
The transmission does not exhibit any evidence of slippage. And, there are no codes when jumping pins A&B on the ALDL.
Any ideas?
(1) The sound is absent when everything's cold.
(2) The sound is absent if I let the engine warm up to operating temp but do not drive it anywhere.
(3) The sound is present after driving about five miles.
(4) The sound runs concurrent with engine RPM
So, I'm thinking tranny. It's a 4L80E.
Last night I crawled underneath with my screwdriver/stethoscope and auscultated various locations.
(1) The sound is almost absent in the engine oil pan.
(2) The sound is very prominent around the TC housing cover.
(3) There is also a noticeable "clicking" noise inside the tranny pan.
The transmission does not exhibit any evidence of slippage. And, there are no codes when jumping pins A&B on the ALDL.
Any ideas?