I needed a cheap truck, found a decent condition 2008 F150 4.6 2wd (4r75e transmission) for auction with hail damage and bought it for cheap! I've put about 4000k miles on it. When the transmission is cold I put it in drive and theirs no issues. but once the transmission is up to temp and I shift into reverse or park, and then back in the drive it feels like its in neutral until the the rpm reaches 1800 and it slams into gear! For the last few months I just put in low when starting out and once im moving shift into drive and everything good to go, Theirs no issues once the truck is in drive! I replaced the fluid and filter, and the fluid is full! Called a small transmission yesterday and talked to the guy he said its more then likely a week fluid pump. It looks fairly easy to replace, just pulling transmission, any other ideas?
First thing to check is the NSS. They sometimes work loose and here's what happens: The switch "follows" the shaft instead of going through the switch positions. The shifter is in D, but the computer thinks the trans is in neutral, so it defaults to bypass pressures. It's also simply possible that the switch is just fragged. Ford was known for that.
This doesn't always happen, but most of the time when a trans pump goes bad, you get a whine that sounds a lot like a dry PS pump. You also mention that once it engages, it's fine. A weak pump should theoretically let it drop to neutral everytime you're below a certain RPM.
Also when it's acting up check the dipstick for bubbles. Someone might have torn the rubber washer where the filter pops in and you're sucking air.
That NSS doesn't explain the cold operation, other than maybe the bypass pressure is high enough to engage the gear.
I'm not sure I knew anything about the 4R70/75 valve body. Also possible that a piston or servo is sticking until it gets enough pressure?
Also, how many miles overall? If you're pulling the transmission and taking out the pump, that's 90% of the way to a complete rebuild. If I'm pulling a transmission out of a vehicle, it almost always gets rebuilt unless it has 20k on it or something. Not doing it is kind of like pulling a piston and re-using the rings. You're doing open heart surgery, might as well do it all while you're apart.
Another possibility is to find a low-mileage junkyard unit.
Mr_Asa
PowerDork
1/8/22 6:29 p.m.
Is there a MAP on that truck? If so,, Ford programmed it so that it helped with shift points. When mine went bad it shifted like I had been rear ended.
Cold it could be in open loop mode and not using it for shifting.
Have you checked the fluid level?
In reply to Curtis73 (Forum Supporter) :
It has 186k miles, I'm willing to do a full rebuild, I just have never open up a transmission, but it could be a good learning experience for a some what simple transmission! Their is a slight whine in the trans but only in first gear!
In reply to dean1484 :
Yes, did a drain and fill with valvoline max life and changed the filter.
In reply to Mr_Asa :
Once I'm actually in drive it shift great, the problem is getting into drive while the trans is hot, I have to shift in L and start moving and then shift in to Drive!
I suggest you join and then post your question here: Ford Truck Enthusiasts Forums - Ford truck and SUV owners and enthusiasts Community And Information Source. (ford-trucks.com)
Use the transmission forum as there are a number of Ford techs lurking there.
