I have a 1989 f150 with the M5OD. When I'm driving and go the put it into overdrive when trying to get up to speed it just starts to slow down unless in going down hill. Is something wrong with my transmission on am I mistaken as to what the overdrive is for on this truck. The cluch isn't slipping nor is the fluid level low. Any help would be appreciated.

 

Yes, it is. That's exactly what you're describing. How many miles on that clutch? Was the flywheel resurfaced the last time it was replaced? Click this, read the caption, & the NEXT few:


(phone app link)

 

FWIW, found with my 5.0L AOD, it didn't have enough 'oomph' to pull itself in OD along on anything more than a long flat stretch. Between the massive 185hp engine rating with the related hp actually available at the less-than-max-hp slower engine speeds, and offered aerodynamics rating right up there with a brick wall - just didn't have the available extra power to pull itself up any kind of grade without downshifting. As a result, rarely used the clunk-in, clunk-out overdrive, leaving it in the regular, or 2nd 'D' position. Not a great solution, but it worked.

 

I believe the cluch had been changed right before I bought but not sure. I'm going on 2 years of owning it and it has done it from the beginning. I believe I've only put 10000 miles on it in the last 2 years

 

So you're saying you don't KNOW how many miles are on that clutch.

It's slipping.

 

No it's not slipping. From what I can tell. When in 5/OD and put the peddle to the floor. The speed goes down along with the rpms. If it was slipping the speed should go down while the rpms go up.

 

OK, well, good luck with that.

 

Are gears 1-4 operating properly? If you get on the throttle does it act like it should? What rpms do you see when you shift into 5th at say, 50mph?