Transmission fluid do or don’t??

[Dsimm321]

hello all,
I pitched a 03 Explorer NBX with 240k miles
I’m trying to do some maintenance. Before winter.
I want to do a transmission flush but I’m worried about what “mechanic Google” had to say.
I have no info about anything done to the suv.
But I want to clean it up and make it last.
So changing the fluid seems like what to do.
I worried that if I change the fluid it will show me issues after. And I don’t have the money to replace or rebuild the transmission.
So my question is. Should I change the fluid to new or wait. Or do I have other options???
I am haveing no issues as of now.

 

[koda2000]

I wouldn't do a flush. Just do a pan drop, filter change and refill with fresh Mercon V. I'd be concerned what a flush might break loose in a high mileage trans and with that many miles on a 5R55 doing a flush might hasten its demise. It's not a the most durable transmission to begin with.

One way to assess previous transmission maintenance is to examine the color and smell of the trans fluid. If it's pink and doesn't smell burnt it's seen maintenance in the past.

 

[Dsimm321]

Thank you. I will check it out tonigh after work.

 

[koda2000]

Thank you. I will check it out tonigh after work.

BTW - I have an '01 ST and before dropping my trans pan I checked the fluid level. It was right where it was supposed to be before draining. After draining the fluid into an empty drain pan I measured what came out. On my '01 5R55 it measured about 4.5 qts. After changing the filter (I prefer to use Motorcraft or WIX trans filters) I put in about 4.5 qts of Castrol Mercon v (because it was on sale at Advance) and the level was spot on.

The Ford OE trans pan gasket is supposed to be reusable and has little metal slugs to prevent over-tightening the pan bolts, but I used the new gasket that came with my WIX filter following their directions to coat it with some grease. It's been over 2 years now and no leaks or seepage, I also added a universal B&M transmission drain plug as I planned to drain and fill a second time, because my fluid was black. Dropping the pan is not particularly difficult, but it is a super messy job. Some here use a transfer pump down the fill/dipstick tube to get as much fluid as possible out of the pan before dropping the pan to lessen the spillage. That might be a good idea.

 

[CDW6212R]

Just replace the ATF and filter, as much as you can. Flushing a trans moves fluid around in the valve body, and any tiny debris can create issues, and kill the trans. So flushing a trans is almost never a good idea, I'd never do that. Replacing fluid is always a good idea, as well as changing solenoids, or accumulators, or installing a VB correction kit, or any Sonnax upgrades that are available. Do what you can, get help from an expert for the hard things.

 

[imp]

Just replace the ATF and filter, as much as you can. Flushing a trans moves fluid around in the valve body, and any tiny debris can create issues, and kill the trans. So flushing a trans is almost never a good idea, I'd never do that. Replacing fluid is always a good idea, as well as changing solenoids, or accumulators, or installing a VB correction kit, or any Sonnax upgrades that are available. Do what you can, get help from an expert for the hard things.

@CDW6212R
I may be off-base, but doesn't normal operation of a hydraulic device like an A.T. always keep moving fluid in and out of control valves? imp

 

[CDW6212R]

@CDW6212R
I may be off-base, but doesn't normal operation of a hydraulic device like an A.T. always keep moving fluid in and out of control valves? imp

Yes but normally fluid isn't going backwards in the TC, and the passages leading to and from it. As I understand flushing, the point is to dislodge any debris stuck in places that fluid only goes one way. I've had many valve bodies apart, and most proper running units will still have tiny pockets of sediment in many corners inside the VB. A poor running trans will have tons of material. It's those kinds of transmissions that a flush will likely kill immediately, dislodging large amounts of debris will foul something in the VB quickly.

If I thought a trans was having some accumulation of material, I'd much rather R&R the VB(and/or accumulators) and manually clean it. That would be far safer and better for the trans, than flushing(forcing/mixing) it all up.

 

[GT2000]

Well I did do a flush on my 98 exp with 140k which had some nasty fluid in it, idk may have been original who knows, but knock on wood couple hundred miles later and shifts way better then it used too, however, this was a 4R70W trans. But i think i do agree with the other guys, with that many miles, just do a change.