I had some slipping while towing in overdrive, does my transmission need a rebuild?

[Triskal]

I have a 2008 Explorer Limited 4.0V6, 5 speed auto, 4x4 with the factory class III hitch. I was towing a camper last fall on a hilly and windy stretch of highway and I had 2 instances of slippage where the engine revved up without any increase in speed. I believe both cases were while going up hill (I'm in the Midwest so these were mild hills). In each case I came to a stop as soon as I could and turned the engine off for a time. After that I got off the highway and used local slower speed roads the rest of the way and had no more issues. While camping I took it to a local transmission shop and he drove it a bit without the trailer but got no codes on his diagnostic tool. I also learned that I should have turned off overdrive in the conditions I was driving in.

That guy recommended against any kind of fluid flush or power flush and said it will likely need a transmission rebuild. After the weekend I was able to tow back home using local roads and leaving overdrive off and had no issues. When I got back home I talked with a local transmission shop (that everyone in town recommends) and just based on my description he said unequivocally that it needs a transmission rebuild.

This is our main daily driver and my wife and I have been driving around since then including through a snowy winter, some highway day trips, towing a couple small utility trailers around town, and I moved my camper before winter to its storage spot - again without using overdrive - all without issue.

So I am curious if any of you had any similar experience and what you did. Do you think the rebuild is inevitable or is there something less expensive you would recommend?

Please don't hit me over the head about towing with overdrive off - I've learned that lesson

Thanks

 

[94Eddie]

Unfortunately, the 5R55 transmission in your Explorer is well known for needing a rebuild/replacement anytime after 100k miles. Not saying yours is one of them yet but the odds are fairly high this is the case. You might consider dropping the transmission pan, changing the filter and refilling. Also, looking at whether the bands in the transmission need adjusted is another item. Doing the above might allow you to get quite a few more miles out of it.

 

[Mbrooks420]

Miles? Fluid color?

 

[Triskal]

Miles? Fluid color?

Approaching 200k. I have not looked at the fluid yet. There is no dipstick and I have not crawled underneath to check yet.

I just talked to another shop and they suggested a flush and refill with synthetic might be all that is needed but that could also reveal more problems. Might be worth the $180 gamble to save $2500

 

[Mbrooks420]

I’ve never once known a transmission fluid change AFTER an issue making a transmission better.

 

[Mbrooks420]

That’s a lot of miles for towing stuff around.

 

[Triskal]

I’ve never once known a transmission fluid change AFTER an issue making a transmission better.

His explanation was that the conventional fluid can't handle the heat and loses viscosity and that is what caused the slipping. Synthetic can handle more heat.

 

[Explorer_PL]

200k on 5R is rare so you may need a new one.
Our 07 with the v6 was owned by a lady since day one, never towed anything, driven like a passenger car and the tranny lost most of its gears at 117k.

To tranny experts:
What about the servos sleeves ? Would leaky bores cause the RPM jumps ?

 

[Josh P]

Approaching 200k. I have not looked at the fluid yet. There is no dipstick and I have not crawled underneath to check yet.

I just talked to another shop and they suggested a flush and refill with synthetic might be all that is needed but that could also reveal more problems. Might be worth the $180 gamble to save $2500

Not much of a gamble, your transmission is on borrowed time.

 

[michael loibl]

Are you sure it was actually slipping and not just reacting to the hill and downshifting or unlocking the torque converter that was causing the rpm to rise without an increase in vehicle speed?

 

[J_C]

His explanation was that the conventional fluid can't handle the heat and loses viscosity and that is what caused the slipping. Synthetic can handle more heat.

Yes, conventional fluid can't stand the heat but if you have ran the same fluid for a long time (factory fill?), odds are that new fluid will be less viscous, more slippy, and more easily cause the slippage. However, your factory fill might have been synthetic. Wait, no, now that I think about it, the 5R55 stayed on Mercon V right? And Ford specified not to use the LV even when the others (6R) switched to it, so if a synthetic is listed as LV compatible then I wouldn't use it as it's probably not viscous enough.

However I think a lot of this had to do with using overdrive, and you weren't getting torque converter lockup and this overheated and thinned the fluid. I feel like you should get a sample of fluid out and see if it looks burnt, and possibly not do anything besides not tow in overdrive, unless the problem starts happening again more frequently.

If the fluid does look or smell burnt, there are additives you can put in new fluid to increase viscosity, reduce slip.

 

[CDW6212R]

I'd get a look at the fluid first. Unhook a cooler line to the external cooler, and let some out to see it. If it turns out to be very black, full of material, then I'd bet a rebuild is a near future event. If it look fairly okay, I'd have a few things replaced and see how long it will last.

A rebuild includes many parts, some can be done with the pan removed. I prefer to replace everything possible myself when I buy a used vehicle, and those items are typically what are among failed parts causing issues later on. IMO about 95% of all trans failures are due to control items, not the friction/clutch parts or basic gaskets and seals. The solenoids and accumulators are prime wear items, and easily replaced by a competent mechanic. I'd replace those and install any Sonnax VB parts available for that model trans. All of that is great for a used trans, and doesn't need to be again if it turns out a rebuild is required soon anyway.

Skip the flush procedure, that's more about a shop creating business for themselves, it doesn't help a transmission any great amount more than changing the fluid. If the VB is fouled by fine debris, flushing it will dislodge it, which is not a sure thing to not create more problems.

 

[MotorCityFats13]

That’s a lot of miles for towing stuff around.

we all know that is a recipe for blown trans.... its like getting a transfusion after you already died

 

[MotorCityFats13]

if you dont know the maintenance history of the trans and suspect its never been changed dont waste time doing a filter and a fill it will probably end its life.... if the bands cant be adjusted and are slipping or the fiction disks are worn down new fluid will only make it slip more.... if you were able to change the filter but keep the old fluid id say give it a shot

 

[Gary Crist]

Ask this "savior mechanic" a couple of questions.

1. How many times his "special fluid" has fixed a transmission problem.
2. How many times have you rebuilt that transmission a short time after
that flush job.

This is like the old Fram oil filter commercial;

You can pay me now and you can pay me later.