'96 Explorer 4.0l V6 4X4... 214,000 miles. So, I'm having some transmission slippage and was wondering what can be done about it. You see the mileage and the only thing done to the trans was a drain and filter/fluid replacement at 120,000 miles.

Here's what's going on... When cold, in the morning, I put it in drive, trans engages, I move maybe 20 feet and it disengages. I wait up to 20-30 seconds and it engages and slips right back out. I wait, engages, move 50 feet and it disengages. You get the picture. After doing this 4-5 times it will engage and I can drive a 100 miles with no problem. Seems like it need to build up pressure or warm up before it will drive normally. I've checked the fluid and it is at the correct level. I guess my question is, would I be wasting time and money to replace the filter and fluid again or is it just warn out?

I've read when a trans starts slipping after it's warmed up means it needs a rebuild and mine is the opposite.

Any advise you can give me would be greatly appreciated. Thanks.

 

i am FAR from a transmission expert, but one thing comes to mind.

try taking off with the O/D off button pressed and see if it acts differently
then try taking off with the gear shifter in "1" and see if it acts differently.

I m assuming a 5R55 here, but to the best of my knowledge Pressing the OD button engages an extra clutch (to support the sprag), and putting the shifter in "1" engages 2 extra clutches (one to support the sprag and one to provide engine braking).

this may give some of the transmission guru's an idea of what is going on.

also you may try posting your question here: Clutch, Transmission, Differential, Axle & Transfer Case - Ford Truck Enthusiasts Forums

there are some VERY sharp people hanging out in that forum.
good luck and keep us posted!

 

First thing to check is your fluid level. If the fluid is too low, the system can't pressurize, so it slips, and as it slips, it heats the fluid and it expands, as it expands, it can then get enough fluid to pressurize the system.

However, these transmissions require new fluid and a new filter every 30,000 miles, So it should have been on its forth fluid change by the time it did its last one, and you should have performed 3 since then. Heres what happens.

Every time a clutch of band engages, there is always a little momentary slippage, so is engineered in for comfort (smooth shifting) and you are always gonna get some slippage as two surfaces moving at different speeds come in contact. As this brief slipping happens, the surfaces get hot which burns and sheer stresses the fluid in the contact zone, and some of the friction material wears off, which ends up in the fluid. Transmission fluid contains additives which help it maintain its proper viscosity, lubriscosity, etc. as it gets contaminated, but it can only handle so much contamination. Also among its additives are detergents and surfricants which allow the detergent to keep certain contaminants in suspension so they don't accumulate in any passages. When the fluid gets so much stuff in it, it both becomes acidic and corrosive, and can start to damage any seals and will slowly etch the metal, but the fine particles of grit that it has accumulates starts to reach a critical point and the fluid starts to act like a polishing compound.

If the fluid is changed often enough, the fluid never becomes harmful and the transmission lasts much longer.

Obviously the first thing is to make sure you have enough fluid, as low fluid causes more slipping. The next priority is to replace the old fluid. Since it has been so long since your last fluid change, simply dropping the pan and replacing the filter will not be adequate. In addition to that, you need to perform a dynamic fluid exchange. Here are the steps.

1: Drop the pan and replace the filter. Take special notice of what is on the bottom of the pan. If there are metal shavings, then there is hard metal damage and that will need to be dealt with at some point. Clean and replace the pan, then refill the trans.

2: Disconnect the return line from the transmission cooler and route it to a 5 gallon bucket.

3: Turn the engine on. The old fluid should begin pumping out and into the bucket. The goal here is to keep adding new fresh fluid to the trans as old irty fluid is pumping out. Keep doing this until either dirty fluid is no longer pumping out, or until a total of 12 quarts of new fluid has been added. While doing this, it doesn't hurt to manually cycle through each position on the gear selector to make sure the new fluid replaces any old in each circuit. Reconnect the return line.

4: Make sure the fluid is at the correct level, then take it for a test drive. After the test drive verify the correct fluid level again.

As far as what fluid to use, use MerconV. There is no need for any special additives, I find most additives either mask real problems until it is too late, or they create new problems. Do not use a generic multi-transmission formula, even if it says it meets MerconV specs. Use only real MerconV. I have seen simple fluid changes work miracles sometimes. It depends on how much life is left in the friction surfaces, and if any hard parts damage has occurred.

 

Kham: good description. If you turn off the engine will it stop flowing from the line?
I think I'm gonna do my own flush, I dont trust these shops to put in the Mercon V.

 

Yes, the pump is driven by the engine, so if you shut the engine off, the fluid will stop.