westhurmond

Hello,
91 F150 XLT Lariat 4.9. It's new to me and I have been working through some issues. Have had the transmission seals replaced and new fluid installed. Recently I noticed that when I put the car in REVERSE and start going backwards it acts like the brakes on are and jumps and jolts a lot until you get going. It doesn't appear to be the engine jumping, just the act of going in reverse causes it. This action physically makes the truck jump up like you are backing up quickly over some large bumps. Is it possible this is the transmission not getting into reverse gear? Forward gears are working fine.

Steve83

You need to put the transmission MODEL in your signature. At this point, I can't even tell if it's manual or automatic. Follow the links in this caption if necessary to ID the model:


(phone app link)

Who replaced the seals & fluid? What brand & type of fluild? Can you tell if it has been rebuilt before? How recently (time/miles) did this symptom appear? How long was it after the seals & fluid? Have you ever checked the engine/trans mounts? Have you ever serviced the rear axle or front suspension?

westhurmond

Automatic. I will get back to you on the model.Seals and fluid replaced by local transmission shop. I am not sure if it was rebuilt before. He didn't say brand and type of fluid. He did say that this particular Ford transmission was a solid one and that he did not see any metal in the pan so he felt like replacing the seals and changing the fluid should keep it going. Symptom appeared recently, yes after the service, but I can't say it was immediately. I have not check the mounts. I have not serviced the rear axle or front suspension.
Are you suggesting that I should check the mounts because maybe one or two are broken and/or loose and this could cause the issue?
What am I checking on front and rear axles and suspension?
When you say serviced the rear axle do you mean change differential fluid?
Sorry for the dumb questions, but I am learning as I go.
Probably should have included that I checked my codes a few weeks back and one is the 628 rc Excessive converter clutch slippage. Is the referring to the Torque Converter?

Steve83

Pass by there when you have a chance, and ask them what they think is causing this symptom - if it's related to their service.Ask those, too.It doesn't have to be immediate. New fluid can cause latent problems to appear gradually, or suddenly. And everyone makes simple mistakes - maybe they left something loose, and it vibrated out as you were driving. Just ask them to give it a quick once-over for you.Yes, it's VERY common (moreso than most owners realize) for these engine mounts to break. The trans mounts break far more rarely, but I have seen it; especially when both engine mounts have been broken for a long time.



Loose/worn/damaged parts on the front; differential damage on the rear.Yes, if you had dumped the fluid, you'd have seen it if there was something wrong with the diff or R&P.



No, it's the clutch inside the trans that locks up the torque converter. That might be one of those latent problems appearing due to the new or incorrect fluid (anything other than MotorCraft Mercon).