I've been trying to find the cause of a high frequency vibration under acceleration for a few months. Feels like a bad bearing. Found a bad wheel bearing and replaced it. No change. Replaced both axles and the other wheel bearing. No change. So, before tearing back into things, I pulled a sample of transmission fluid (out of the dipstick tube) to hopefully rule out any transaxle problems.
Well, got the results today. It starts with "there's a lot of metal in this sample". There's 20k miles on the fluid. Did a flush (Gibbon's method, 16 qts total) of the original fluid at 147k miles.
So, the results:
Aluminum: 61, Avg-21
Copper: 192, Avg-85
Lead: 105, Avg-31
Average is for a Volvo automatic with 25k miles on the fluid.
So, not pretty and could be indicative of a bad bearing in the transaxle. It shifts fine.
So, how do I verify that something is wrong with the transaxle? I can pull the drain plug and see if there's any "glitter". Pulling the transmission is obvious a major and expensive effort. So, I want to be positive before I go down that path.