i have a 2000 ford f-150 v6 5-speed man. with 106,000 miles on it. i noticed that when i upshift into 4th gear it grinds about 80% of the time, but it doesn't do it in any other gear. it also does not do it when i am downshifting. does anyone know what can cause this and how can i fix this. thanks for the info!
-matt

 

synchros? whats the oil level?

 

Have you been under the truck and inspected the transmission?
Have you checked and/or changed the fluid?
There are some rubber plugs on top of the transmission that can leak, causing a loss of fluid.
I seem to remember problems with 4th gear being the first sign of a problem with low fluid.
I suggest draining the fluid and refilling to proper level with ATF.
And, look closely for signs of a leak. I have been told the fluid will leak while driving, and this can cause the fluid to blow back, not drip straight down the transmission housing.

Here's some info on an easy drian - refill for the M5OD transmission.
https://www.ford-trucks.com/forums/s...d.php?t=204530

 

i bought the truck on Dec 23, 2004 and it had 92,000 miles on it so i'm sure the trans. fluid has never been changed. i will try this this weekend and check for leaks- thanks for the info.
-matt