Bad idea to change trans fluid on older truck?


Sworn

Sworn

15+ Year Member

Joined
Dec 10, 2007
Messages
215
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3,101
Vehicle Year
2008 FX4 Ranger
Transmission
Automatic
Okay, here's the short version. I think my truck is leaking trans fluid from around the pan.

I mentioned this to my neighbor, who is a fairly knowledgeable guy. I further related to him that I was going to get a new trans pan gasket and a fluid change.......My neighbor said it might not be the best idea to change the fluid and here's why.....If the fluid is not changed on an older vehicle it tends to develop a bit of "grit" in the fluid. In an auto trans the older fluid with aforementioned "grit" helps older and worn clutches engage. If brand new fluid is used the clutches have less to grab on to.

Anyway this is what I was told, and I would like to get some input from you guys. Thanks in advance!
 
I'd revise your opinion of your neighbor if I were you.

Listening to myths is not knowledge.

Do you REALLY think grit in moving parts is a good thing?
 
I've heard this idea too... But then again I have never flushed any auto I've ever owned..

My 2001 I only had for 25K miles, and so far that's about what i've put on my SD. It may be due for one soon.

The fiancee's ranger has 101K, it was just flushed by the previous owner at 90K.
 
I'd revise your opinion of your neighbor if I were you.

Listening to myths is not knowledge.

Do you REALLY think grit in moving parts is a good thing?
Click to expand...

It sounded plausible.... That's why I posted the question.
 
its alright to just change the fluid in the transmission and put a new filter but do not have it flushed. do not touch the fluid in the torque converter.
 
Because the ATF gremlins will "get" you.

Flushing the transmission is fine. It may expose a preexisting problem that you didn't notice over all the other problems, but it simply will not cause them on its own.

I'd like to know who came up with the idea that dirt can hold things together. JehEEzus, I'd like to know what he was smoking.
 
why not flush the torque converter? Why not flush the trans?? That bit about the "grit" in the oil helps the clutchs grab better is halarious. Its the grit that creats slugish shifts by making the vakves stick. If its a ferros metal paticals, they will actualy be atracted to shift valves that are solinoid operated. it will clog the trans pump pick up screen. If the grit was good, firsters wouldnt exist. Your nieghbor may be well informed on some topics BUT auto tranys isnt one of them. Try talking to a guy who works on tranys all day, or somone whos good with hydraulics. They will both tell you that anything floating around in oil is not good.
 
You can flush the tranny if you want, in fact, I recommend it. I recently had my A4LD flushed after 70k miles on the previous fluid. (my dad was never big on tranny maintenance but I'm taking care of the cars now, and I say auto trannies need flushes every 30k) So far, it's been about 1000 miles and the transmission still works perfectly.
 
I differ in opinion with most of the posts here. When you flush an older transmission, it can break up all the built up crud in the hydraulics, which can make their way to the pump, clog it, and cause it to fail. I lost my first transmission because I flushed it at 70K (yeah I know, it was very late), and the pump failed about 100 miles later. The transmission shop that rebuilt it (very trustworthy, I subcontract all my shop's transmission work to them) said that the pumped had to work overtime to compensate for being clogged, and as such went boom.

Take it for what it's worth, it's just my experience. I think flushing is a good thing; however, on older cars I will not touch them or offer a warranty on the flush because I've seen what has happened to my and friends' transmissions that I flushed.
 
punp had to work over time? The pumps being driven by the engine, and any kinda "clog" woild get either sucked right through, OR starve the pump and then it will burn up. Its just a hydraulic pump that fills the torque converter and provides lube oil and "supply/apply" oil to operate the trany through its ranges. Take this for what its worth. Automatic tranys get neglected. They are the last thing more people thing about during a normal service. YET, they are the first thing bitched about when they dont work. There is nothing wrong with properly flushing out a trany. All it does is pump clean fluid through the trany untill al lthe old contaminated fluid is washed out. Also, when trany fluit smells/looks burnt, thats the additives in the fluid breaking down due to heat. so, never changing the fluid is foolishness. changing fluids and flushing does not cause problems. IT MAY however reveal problems that went un noticed
 
Ranger5.0 said:
punp had to work over time? The pumps being driven by the engine, and any kinda "clog" woild get either sucked right through, OR starve the pump and then it will burn up. Its just a hydraulic pump that fills the torque converter and provides lube oil and "supply/apply" oil to operate the trany through its ranges. Take this for what its worth. Automatic tranys get neglected. They are the last thing more people thing about during a normal service. YET, they are the first thing bitched about when they dont work. There is nothing wrong with properly flushing out a trany. All it does is pump clean fluid through the trany untill al lthe old contaminated fluid is washed out. Also, when trany fluit smells/looks burnt, thats the additives in the fluid breaking down due to heat. so, never changing the fluid is foolishness. changing fluids and flushing does not cause problems. IT MAY however reveal problems that went un noticed
Click to expand...

It wouldn't get sucked right through if enough crap is broken up. I'm not talking about little stuff, I'm talking small pieces of clutch and band material that is broken up by the fresh fluid being introduced. Even though the pump is driven by the engine, it will still clog and it will require more power to push enough fluid through. I should get the pictures of how bad my pump looked when they took it out in pieces (it's a two piece I believe on the 4R44E). If the pump is clogged, it won't force enough fluid through for a proper shift, which will hurt a transmission over the long run. I'm sorry, but I disagree, based on my experience (mostly Fords and Audi 5 speed autos) that flushing a transmission on an older vehicle is always a good idea.

Also, without draining the torque converter, you're far from getting the majority of the old fluid out. You're really just mixing new fluid with old fluid. I had my torque converter tapped with a drain so I could get all the fluid out.
 
If this was my truck I'd be looking at it this way- if the gasket's leaking, go ahead and fix it, as leaking gaskets don't heal themselves (at least I ain't ever seen one do it!). Why have to keep checking the level, topping it off, and/or run the risk of running the fluid too low? In the process of replacing the gasket you'll be draining most of the old fluid; throw a new filter in it while you're at it, and refill it with new fluid. Just an opinion, and good luck whichever way you go with it.
 
so where does all the pieces of clutch materieal get stuck in the pump? do you understand the basic principals of hydraulic pumps? Whats the oil circuit in most auto trannys?
 
further more, if there is shit that big breaking lose, or kinda floating around in there, then the trany is already on its way out. Flushing a trans does NOT hurt it. Its not being blasted with high pressure cleaning fluids. Its juss getting some clean oil circulated through it. And no, flushing does not help with the oil in the torque converter, but most auto/light truck converters have drains. Every converter used in large applications has a drain, but is seldom used for some reason. Most likly its from people talking about the ATF monsters lol.
 
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