'10 ST 4.0 Shifting Issues

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thehof2012

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I posted about this earlier but didn't get a reply, hoping someone can chime in.

My ST has intermittent issues where it doesn't want to engage into R, it lags a few seconds. I have a new filter on order and plan to change out at least the 5qts in the pan and filter, wondering if/what else I should review/replace while I'm this far into it.

I found a kit that includes a new solenoid block and I'm tempted to purchase it and replace, but I honestly don't know enough on where the issue could lie. A few questions:

- If my reverse band was broken, there would be no reverse at all, right? Since I have reverse, it just takes a few seconds to engage (intermittently), I'm hoping/assuming the band is not broken?
- If the band isn't broken, and the issue is largely in R (sometimes in 1st gear from a stop, but almost never), would this point to the reverse servo going out, or it's screen being clogged and not allowing enough fluid/pressure to build up to engage it into reverse? Or, is it more likely that the solenoid block is causing the issue?
- If I want to lengthen the life of this tranny (5R55S), should I replace the solenoid block to see if this resolves the issue?

Just trying to get some feedback as to what I should be looking at when I have the pan off this weekend. Any thoughts appreciated!
 

DILLARD000

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Certainly not knowledgable\familiar with the 5r55s, so take my comments as such.
But Slow\No shifting into Reverse is a symptom of declining\failing ATF pressure.
Could be due to several things in the Tranny.
Has the Tranny ATF+Filter ever been replaced before?
I'd start by doing a PanDrop, new Filter, new PanGasket, refresh ATF.
Consider adding a Drain Bung+Plug\FumotoValve to the pan to allow easier
draining+refilling several times to get a full replacement with new ATF..
Adjust the Bands while your there.
Replacing the Solenoids may help, maybe.
May have leaky\worn ValveBody components; so a rebuilt VB may help.
Commercial "Tranny Flush" machines have been reported doing more harm than good.
Do you have any OBD2 TroubleCodes?
 

OvalSports

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I would check another forums that uses those tranny’s.
Definitely fluid and filter change, too many people ignore this then complain when their tranny fails. It costs more for a good granny than it does for an engine, so keep those fluids changed.
Something else, if this is primarily happening at the beginning of a drive, I would let the car warm up first. You can even cycle the gears to help with the warm up.
 

thehof2012

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I don't have any history of the transmission fluid or filter being changed. I have a new filter that just was delivered, assumed that was the best first step.

The transmission doesn't have a "fill" at the top (no dip stick) it's completely sealed with a drain plug on the bottom of the pan to check level and drain when needed. I'm just debating if I should buy a rebuilt valve body and/or solenoid pack now and replace it all while I'm there, or what to do.

I don't have any OBD codes which is quite odd, too.

There's a guy I know that has a 5R55E tranny w/ 20k mi on it but I doubt that would work as a replacement? (5R55E vs. 5R55S)

Just seems pretty odd, but since I still have reverse and all forward gears, I'm hoping there are no broken bands internally.
 

OvalSports

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I would try the tranny fluid and filter change first. Typically initial fluid changes are followed by another shortly after when a full system flush is not performed. You can always try swapping those during the next change if there no improvement from the initial change.
 

EddieS'04

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The transmission doesn't have a "fill" at the top (no dip stick)
There is a plug where the dipstick would be. Dipstick is under the plug. You will need a funnel and tubing that will fit the plug hole, and reach engine compartment. Easiest if possible is to measure the amount drained. put that much back. It is sort of hard to use the stupid dipstick
 

thehof2012

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There is a plug where the dipstick would be. Dipstick is under the plug. You will need a funnel and tubing that will fit the plug hole, and reach engine compartment. Easiest if possible is to measure the amount drained. put that much back. It is sort of hard to use the stupid dipstick
Eddie, There isn't an actual "dip stick" itself, but there's a hole on top I could utilize for "top filling" vs. pumping it in from the bottom? That's nice to know!

Interesting.. I will be checking this out further (hopefully this weekend)
 

Todd Z

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Eddie, There isn't an actual "dip stick" itself, but there's a hole on top I could utilize for "top filling" vs. pumping it in from the bottom? That's nice to know!

Interesting.. I will be checking this out further (hopefully this weekend)
NOT on the v6.... that's the v8.... the v6 uses the bottom fill plug that you need a pump for.
 

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