Local Crown Vic owner contacted me last week about his recently purchased CVPI suddenly loosing Overdrive.
It's quite common for the 2004-2005 transmissions to break the Overdrive servo retaining ring and the broken pieces find their way into the valve body and lodge in the OD servo regulator valve.
This causes the valve to become stuck in the exhaust position and OD servo will not apply. While this seems to be more common on F-150 trucks, it does happen to the CVPI models also. This failure is common enough that there is an updated, hardened retaining clip available
Originally, He wanted to bring the car to me to get fixed, but we couldn't get our schedules to align.
He decided to try the repair I mentioned on his own and with the help of a friend they got the valve body removed.
With the valve body removed, they discovered, on this transmission the OD servo retaining clip was still intact. However, the valve in question
still needed to be checked for proper operation and make sure there was no debris.
With my guidance over the phone, he got the valve body apart, located the correct valve and confirmed there was debris causing the valve to hang open.
It's not clear where the metal piece came from, but it was removed and confirmed the valve operated normally.
The valve body was reassembled, installed on the transmission, torqued to spec and the transmission filled with fresh fluid.
The owner reports the transmission has Overdrive again.