5R55E overheating after rebuild swap

[AyyAre15]

I purchased a rebuild from a guy in my state.. put it in.. everything was good to go but recently I noticed it starts slipping and hesitating to shift when it’s been driven 20-25 minutes. It’s fine in my drive to work, fine on the way home.. but if it’s driven longer it’ll start acting up. I checked the cooler lines today and had good flow at the return line but noticed the fluid doesn’t seem any cooler.
Or if it is, it’s not much cooler. What else could be bad if I have good flow and normally no issues with the transmission? Appreciate any help.

Fluid and fluid level are good. I’ve checked the up to temp in park on a level surface about twenty times. Thought I should include that detail, thanks

 

[wollimann]

My first thought was the thermal bypass valve, sitting in the valve body, should open at 70°C / 158°F
I am not shure if this valve is still available, i didn't found it. They often fails in the past, oil/bands/clutches get burned.
So i block this valve with a little part, so the oil runs every time through the cooler and the additional cooler.

This part was included in this superior shift kit, but you also can use a matching copper pipe part.

 

[wollimann]

I purchased a rebuild

Did you know exactly what he's doing with the 5R55E?
Valve body, solenoids, pump, bands, clutches, seals, servo pistons...
Band alignment?

 

[AyyAre15]

Did you know exactly what he's doing with the 5R55E?
Valve body, solenoids, pump, bands, clutches, seals, servo pistons...
Band alignment?

Did you know exactly what he's doing with the 5R55E?
Valve body, solenoids, pump, bands, clutches, seals, servo pistons...
Band alignment?

Not at all.. it was 6200 for a rebuild and warranty locally.. so I found one from marketplace in a project they were calling it quits on. He said it got a new reverse, 1st and new updated valve body. I remember him saying he adjusted the bands but I don’t know much about transmissions. I was just happy to have survived the swap and it worked

I figure I am likely getting what I paid for but thought I might ask on here for some solutions to check out.

Did you know exactly what he's doing with the 5R55E?
Valve body, solenoids, pump, bands, clutches, seals, servo pistons...
Band alignment?

Not at all.. it was 6200 for a rebuild and warranty locally.. so I found one from marketplace in a project they were calling it quits on. He said it got a new reverse, 1st and new updated valve body. I remember him saying he adjusted the bands but I don’t know much about transmissions. I was just happy to have survived the swap and it worked

I figure I am likely getting what I paid for but thought I might ask on here for some solutions to check out.

 

[AyyAre15]

Did you know exactly what he's doing with the 5R55E?
Valve body, solenoids, pump, bands, clutches, seals, servo pistons...
Band alignment?

My first thought was the thermal bypass valve, sitting in the valve body, should open at 70°C / 158°F
I am not shure if this valve is still available, i didn't found it. They often fails in the past, oil/bands/clutches get burned.
So i block this valve with a little part, so the oil runs every time through the cooler and the additional cooler.
View attachment 464754
View attachment 464755

This part was included in this superior shift kit, but you also can use a matching copper pipe part.
View attachment 464756

Thanks I will look into this. Appreciate ya!

 

[wollimann]

He said it got a new reverse, 1st and new updated valve body.

That's not so much information, but a updated valve body should be tested by the seller.
The thermal bypass element has always the risk of failing, so i would recommend to
get free flow for the transmission oil.
If not present i also recommend installing a auxiliary transmission oil cooler,
inside the returnline.
In any kind of transmission rebuild Ford recommends to install a inline filter (returnline).

recently I noticed it starts slipping and hesitating to shift when it’s been driven 20-25 minutes.

Can you say which gears hesitate?
Any DTC's, OBD reader present?
Blinking OD lamp?
MerconV should be inside?
Transmission range sensor alignment correct?
Band alignment correct?

You have to take care of the transmission oil temperature, slipping is a sign of
insufficient oil pressure if temperature rises or gets too high.
So it is important to get the matching pressure in every gear, could be read out
at the tranny pressure test port.
But you cant figure out which internal part causes the pressure loss, if you don't
know exactly if the servo pistons/bands/clutch plates/clutch piston seals are in good shape.

It is not a satisfying circumstance for you, but so it is with so called rebuilds.
Hope that is "only" a temperature problem.