Advice on 4.0 ohv transmission

[Advanced Thanks]

I have a 97 explorer with a 4.0 ohv with 150000 miles on it. It's the four speed transmission, 2 wheel drive. I would like to change the filter and fluid. The fluid is brown with a lil pink left. I don't know if it's ever been changed. I've been told that doing anything to it could possibly mess it up. I need advice. Thanks.

 

[daisyrocky]

Did it to my 97 Explorer 5 years ago when I pick it up. Transmission never ran right ever since and had to take the tranny apart for rebuild. But on my 95 did the tranny flush and all and been changing tranny fluid every 3-4 years with no issues at all. Maybe it's the Mercon V on the 97? I'm still baffled till this day and wondering should've never touch that 97 tranny fluid. Brought that 97 for 800.00 and only problem was the tranny issues after the flush. Ended up spending extra 1500.00 for the tranny build. Wonder how far that 97 went without touching the tranny fluid?

 

[Advanced Thanks]

Thank you. I paid 650 for it. I didn't really wanna flush it. Maybe just change what comes out with the filter change. Or maybe just change the filter and reuse the fluid. Idk. Thanks for the input though.

 

[lobo411]

There's no point to dropping the pan if you're just going to reuse the fluid. Just do a standard filter/gasket replacement and refill with the appropriate fluid, which on mine (96) is Mercon V.

And I wouldn't do a flush. I don't know if anyone has ever proven that they actually do anything besides eat up people's money, and I'd be worried that the pressure would blow out the seals on an old trans.

 

[Rhett]

Unless you just want to drive it into the ground, it's my belief that it's always good to drop the pan, change filter, and exchange the fluid, even on an old trans. I think if your tranny misbehaves after this service, then it was going out anyway. That means crud and dirt and sludge was all that was keeping it from slipping -- not exactly confidence-inspiring, more like it would go out on you on that trip far from home on a deserted road.

I don't like those pressure flush machines for the reasons lobo mentions. Instead let the transmission pump out the fluid itself, via the cooler out line. On a 1st gen it pumps one quart out every 7 seconds. As one or two quarts pump out, put in the equivalent of new fluid via the filler neck. There is a good (old) thread here on EF about the procedure (it's pretty simple). You would drop the pan first, and change its filter, before doing to fluid exchange.

 

[Advanced Thanks]

Thank you all for your replies. I agree with your logic Rhet and I don't wanna drive it into the ground. I think I may just change the filter and whatever fluid comes out, see where that gets me and if everything still works then I might change all the fluid after. Thanks again and any one else who may have some input please feel free to add.

 

[lobo411]

Another thing you could do is install a drain plug in the absolute lowest part of the pan. You have to make sure you put it in a spot where it's not going to interfere with anything, but I didn't have any trouble. Seal the threads with teflon tape as well.

Once you get a drain plug in there, you have a choice. You could run the trans pump and get the fluid out that way, or you could drain what's in the pan and get 1/3 or half the fluidl out that way without too much fuss. Then you don't have to mess with the filter or the gasket a second time around just b/c you want to freshen up the trans fluid.

I installed mine about 10 or 15 years ago and haven't had a leak. IIRC, I just went to Autozone or Pep Boys and bought whatever generic kit they had on the shelf. Nothing fancy.

 

[Advanced Thanks]

I'll probably do that so I can transition to new fluid a lil more slowly and maybe not shock the system.

 

[Rhett]

Thank you all for your replies. I agree with your logic Rhet and I don't wanna drive it into the ground. I think I may just change the filter and whatever fluid comes out, see where that gets me and if everything still works then I might change all the fluid after. Thanks again and any one else who may have some input please feel free to add.

If you do that you will only change about 35% (35% on the A4LD. Your 5R55E may be different) of the fluid, the rest is in the torque converter and lines/cooler. You will still have a lot of dirty fluid in there.

 

[Advanced Thanks]

I figured that if I changed it that way four or five times, not back to back mind you, but over the course of a couple of months, then I would eventually get it all or at least a good portion while also doing it slowly. Is my logic correct? Thanks

 

[lobo411]

Last I checked, Mercon V costs $4 or $5 a quart, and a pan drain/refill takes about 4 quarts. To change it 4-5 times requires 16-20 quarts, or $64-$80. Too pricey imo.

Here's what I'd do:
1. Drop pan, change filter and gasket, install drain plug. Be sure to clean the magnet in the pan too.
2. I'm reluctant to run the trans pump to get rid of the rest of the fluid. I'd probably mess it up. Therefore, I'd just button it up and refill with 4-5 quarts of Mercon V
3. Smell the old fluid that you just drained out. Does it smell burned? Does it flow like it should, or is it a bit goopy? If it doesn't smell burned and flows like it should, I wouldn't worry. Just run the vehicle as normal and enjoy being done.

4. If and only if the old fluid smelled burned/behaved abnormally, then I'd run the vehicle a few hundred miles and then smell/inspect what comes up on a dipstick check. Does it still smell burned/look wrong?

If not, leave well enough alone.

If so, drain, refill, run a few hundred miles, and smell again.

 

[Advanced Thanks]

Sounds pretty good. I will definitely inspect quality of fluid before I make a decision on changing it. Thanks.

 

[Rhett]

I figured that if I changed it that way four or five times, not back to back mind you, but over the course of a couple of months, then I would eventually get it all or at least a good portion while also doing it slowly. Is my logic correct? Thanks

I think that's overkill. When I first bought my truck, I was not sure about the previous owner ever changing the fluid. So, I dropped pan, changed filter, and exchanged the fluid thru the cooler lines one time. Then I drove for about 6 months, and did the whole process over. I think 4-5 times is overkill and a waste of time and money.

If it were me I would not just drop the pan. I would also drain thru the cooler lines. You 2nd gen guys have auxiliary transmission coolers, correct?

 

[Advanced Thanks]

Alright fellas, I've decided to change the trans filter. All I can find are car quest, duramax, or the house brand at orielys. I really wanna motor craft or fram but can't find it. Any suggestions on the best filter.

 

[lobo411]

I dunno...usually when I want to do a job like this I order the parts on Amazon or Rockauto before I start. Assuming you have to do it now and can't wait for delivery, I'd say get whichever has the longest warranty and seems to be most durably-constructed. Maybe even go to the parts store and look at the filter before you buy it just to see if it feels like quality or junk.

The thing about X-brand filters is that they can be made by anyone at any point in time. IE, O'Reilly's house brand could be made by Super Duper Filter Co today and Generic Third World Filter Co tomorrow and back to Super Duper Filter Co the next day.

 

[Advanced Thanks]

I went ahead and ordered a motor craft filter from advanced. It should be here in a couple of days. Thanks to all the advice and I'll post the results after I change it. Btw it's a five speed auto trans. Idk how I missed a gear lol.