F150 1997 V6 4.2 transmission flush?

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Jun 15, 2010
I just purchased a 1997 F150 with 100,000 miles on it and have changed all the fluids except for the transmission fluid. The previous owner said he has never changed the fluid previously. It shifts and runs fine, the color is koolaid red with no signs of burning or debris in it. I bought the filter and gasket from Ford, but I have been told by several people not to flush or change the transmission fluid if it's never been done. To do so can free up debris in the system and cause problems. That doesn't sound right to me. Does anyone have any input on this? Winter is upon us and I would have thought it would be best to have good fresh fluid in the transmission. Any thoughts on whether a flush and fill or just dropping the pan and replacing most of the fluid and filter is the way to go? Thanks...
I'd be more concerned with the timing chain/water pump gaskets on the front of that engine. As far as the trans flush goes, don't think I would do it. May be better off just dropping the pan, change the filter, and re-fill. If the fluid isn't real burnt you may be ok doing the flush.
Ive seen that several times on transmissions that originally came with conventional fluid when they were changed after 50,000 miles. I dont know the exact mechanism but suspect the damage was already done and the fresh fluid simply uncovered it. If the truck came with Mercon V (Synthetic Blend), which I believe 1997 was the first year, I would be less concerned about changing it. Of course it would also depend on how the truck was driven and how much it hauled or towed. Sorry I cant say yea or nay to your question.
Drop pan, replace what comes out with fresh fluid. This is safest move since sometimes, and i do mean sometimes, 100% replacement of fluid = no pull when it goes back in. Change the 30% or so you get when you drop the pan, change the filter, refill what came out.
Yes, I'd heard about that gasket and even the cover itself cracking. I did a cooling system pressure test, swapped the oil and coolant, and literally check them daily to watch for any signs of contamination, to which there are thankfully none as yet. To replace the gasket and cover costs $1100.00 including labour and parts at my local Ford dealer... 5.5 hours time, plus $400 cover, $30 gasket, taxes. so it's not something I want to do as a 'prevention' measure. So you're of the opinion to not change the transmission fluid. Have you had bad results from doing so in the past?
Ok, so Gene K says it could be bad news to swap 100% of the fluid, and 45ACP agrees with this. I'm feeling inclined to just drop the pan, change the filter and leave the torque converter alone. How about Lucas transmission additive? Any idea if that'd be a good idea to pop in with the amount of fluid I take out of it?
Gary, I generally dislike oil additives, but I have heard some pretty good things about adding the proper dosage of "Lubegaurd Red" As previously stated I'd be quite hesitant doing a flush.
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Originally Posted By: HM12460
Gary, I generally dislike oil additives, but I have heard some pretty good things about adding the proper dosage of "Lubegaurd Red" As previously stated I'd be quite hesitant doing a flush.
Pretty much +1, the way the fluid looks and smells says a lot. Additives are a hit-or-miss thing. A lot of the time, its best to sue fresh ATF and no additives, though he named a good one and not an "iffy" one like Lucas (which makes no less than two, one thick like syrup and one thin. I dont trust it.) Every car ive had ive line-flushed out roughly one gallon of ATF at any given time within a month of owning it as well as iston soak, coolant flush and a Seafoaming, and the results have been great (no dead cars, very marked performance improvement.) I dont fully believe in changing it all out, since that high mileage stuff, be it in the best condition or absolute worst, does tend to accumulate its own chemistry. Changing either what comes out in a pan drop, or disconnecting the trans line from the radiator and doing it that way, replacing roughly 30-50% is a safer way. Its a great way to get fresh fluid in, and then if it works well, you can do it again in 30,000 miles or less, if you want. The result is new fluid going in, and old fluid being removed. Filter and pan is up to you! Trans cooler line may be an easier way. That also goes a long way towards not upsetting some type of delicate balance the trans MAY have, clean it too much you may do a no pull. Happened with a 1996 Honda Accord "Oh yeah it will be ok, go ahead and flush it!" .. no pull. That guy was [censored] too. Statement was "That wasnt supposed to happen! Everything i read says its not supposed to happen! it should have been fine, this and this and this i researched it yada yada yada" and his car gets pushed out from the lift. No, he was mad.
Just drain what you can and refill with new fluid. I bought an extra capacity pan with a drain plug for this reason. I do this every year. FYI, I just changed the fluid for the first time in my 2001 F150 as well. I believe that it was around 118,000 on the original factory fluid.
Flush it slowly. When I bought my Cherokee last year, I didn't know how long it had been since the transmission fluid was changed (if ,ever). The transmission in that is good in a Crown Vic, but not near heavy duty enough for a pickup that's been used to tow / etc. I drained a few quarts at each oil change. I've never had a single problem with the trans (knock on wood). Just a few weeks ago, I changed ALL of the fluid when the line blew off and I ran it dry!
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I did a pan drop and filter change when I got my '98 F150 at 96K last Oct. 1,000 miles later I did a full flush and replaced the fluid with Amsoil ATF. That was 17,000 miles ago, and the trans is fine. I've done trans fluid flushes on 7 cars in the last 10 years, and every one was near or well over 100K miles. Every vehicle got Amsoil ATF, and none ever had any transmission trouble. Even my wife's '00 Civic (what with that dodgy slushbox Honda was tossing in those cars) didn't grenade after I did a flush at 90K. That was still going strong-about ready for the next fluid change at 120K-when some drunk [censored] hopped the curb and took out that and my '93 Cougar in our driveway. That had 185K miles on it; Did the first trans flush when I got the car at 110K miles. I don't think I'm some kind of anomaly when it comes to old transmission health and trans flushes. If the fluid looks and smells good, and the trans is shifting well I'll do a flush. Nothing has gone sideways yet. But honestly, I would never have purchased a used vehicle that I wasn't confident had every major component in well working order.
In both my ford explorer and my BMW x5. I drain the pan, refill mobil 1 which is dexvi and mercv, drive, drain and refill/drive 2 more times. Has worked like a charm every time I do it every other year (about 30K to 40K on each vehicle). I changed the filter and gasket at 35,000, on both cars, when should it be done again if I am draining and refilling x 3 every other yr?
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