I have a 2005 F150 King Ranch with the 5.4L V-8. I'm not sure which transmission it has. the truck has 160k miles on it and the transmission was rebuilt about 4 years ago.
Very recently when stopped at a red light or in traffic it started feeling like it was jumping out of gear and then back in. I'm thinking the torque converter may be unlocking and locking again.
When I start to go it is still unlocking and then will lock up hard. Once I am moving it is fine, both slow and on the freeway and OD seems to be working fine.
When it started a few days ago I checked the transmission fluid level and it didn't show on the dipstick. I added 2 quarts and it seemed to work fine after.
Today in stop and go traffic it started again, but this time the fluid level is good.
I have noticed it doesn't do this when the engine is cold, but only happens after it has been driven for a while and is at normal temperature.

Any ideas? I do not have a check engine or any other warning light lit on the dash.

Jim

 

Well it doesn't seem to be temperature related. I took it out again after it had cooled off. It did fine cool, but then it also did fine after I got it to normal temperature. I didn't take it on the freeway but I did drive it around 45mph then on residential stretts at 20mph. I went through a Sonic drive through and made several stops at red lights and stop signs with no issues.

It seems to occur after long periods of being stopped while in drive, like in heavy stop and go traffic.

 

Even though you may not think it's temperature related, it still may be getting hotter than you'd like. Do you have a digital gauge showing your trans fluid temp? BTW, you have the 4R75E. Electronic 4 speed rated for 750 ft/lbs.

Your torque converter theory may be correct. A major problem that people have when replacing trans and torque converters are not properly fill the torque converter with fluids before installation. Then, upon start, the clutches are ground significantly, essentially diminishing longevity. A torque converter replacement is much less expensive than a trans rebuild. But don't forget, just because you got a rebuilt transmission years ago doesn't mean it's brand new and should last another 130K miles. Not all internals are replaced. Only clutches, gaskets, snap rings, etc...

My advice would monitor temps with a gauge, then when it persists at a specific temperature, take it to a transmission specialist and then have them diagnose.

Sorry I couldn't be of more help.

 

When I said it doesn't seem to be temp related I meant it didn't matter if the engine temp was cold or at normal temp.
Normal stop and go, like at a red light doesn't seem to initiate the problem, but long periods of being stopped or barely moving like in heavy traffic will eventually cause the problem.

Is the damage already done and I need another torque converter, or would a better transmission cooler fix it?

I bought this truck from my nephew when he decided he needed a 4x4 truck. When he had the transmission problem he had them install a remanufactured transmission rather than having the original rebuilt- if that matters.

 

If the torque converter were to lock while stopped it will stall the engine. So I can guarantee that the converter is always unlocked when you're stopped. You can also eliminate the torque converter as the cause of this problem, it can't cause this.
Usually this is caused by low trans fluid. Then I saw the next line...
The locking and unlocking you were feeling is the forward clutch releasing and reapplying due to low fluid. Between all the release and applys, plus the slams you described, I suspect the forward clutch is damaged.
A damaged clutch will work better when the trans is cold. As it heats up the fluid thins and the seals that are damaged will not be as effective at keeping pressure in the clutch.

I think you're going to need a trans rebuild to fix this.

 

Thank you Mark.
Do you have a wild guess about how soon I would need to have it rebuilt? I need to start planning on a big expense.

 

Mark sounds smarter than me.

I'd do it sooner rather than later. You don't want to be stuck on the side of the road with a blown trans. Also. Replace the trans cooler as well. Fluid, AND metals/gunk/debris go through it. Clean the lines out so your new trans doesn't get any more of that crap inside it.

 

About right now is a wise choice if it has that damage.

D

 

This started about a week ago. It only does it when I am stopped in drive for a long time. Normal stops at lights, etc. don't seem to cause it to happen. When it first happened I checked the fluid level- I had the oil changed a few months ago and they apparently didn't check any fluid levels- or fill the oil, and I trusted them.
It started acting up and when I checked the fluid it was low- not on the stick. I added the amount of fluid it needed and thought it was OK- until Saturday when it started again during a very long traffic delay.
I am going to have to save up the money to get it rebuilt, and until then I need to nurse it along.
I have a short drive to work and will not be taking it on any trips over a few miles, and try hard to avoid heavy traffic.
Would it do any good to drain the fluid, replace the filter, and try to flush the cooler? Would that possibly get me by until I can get it rebuilt? I simply do not have $1,500.00+ laying around for a rebuild.
Does replacing the forward clutch require a full rebuild?

 

Having done this for more time than a lot of people on this forum have been on this earth, I can safely tell you that there is nothing that will get you by if it truly is time to rebuild it. Nothing fixes physical damage other than repairing the physical damage.

Make sure your fluid is positively full. So many people get that wrong you can't imagine. I have gotten into some ridiculous arguments with even professional shops over this. If there is a dry spot on that dipstick below the wet spot you are thinking is the fluid level then the fluid level isn't where you think it is. If the dipstick is immersed in fluid then there can't be a dry spot below the immersion point. It just cannot happen.

D

 

I will double check the fluid level this evening.
Dumb question, but is the forward clutch in the transmission itself or in the torque converter?

 

so low fluid will cause this?
I checked the fluid level right after work and found it wasn't on the stick- again. I know it was full when I last added fluid.
I have a leak somewhere. I will crawl around under the truck and see if I can find it.

 

4 wheel drive? Open the transfer case fill plug, if fluid pours out that's where it went - the seal between the trans and TC needs to be replaced.

 

2wd.

 

It's inside the transmission. The torque converter clutch is the only one inside the torque converter.