conflicting answers about doing a tranny flush.

[E-rex]

Did you change the filter or drop the pan? Pro and con opinions on changing the filter, but my thought it that dropping the pan should not hurt, and could help me know if the tranny is really fouled up and nearing end of life.

Interesting how widely opinions and reported experiences on this vary..

[marret]

Originally Posted by arctictraveller

Did he give you any indication of why it failed or if the failure was related to the flush?

He said the procedure, using the transmission pump to cycle fluid from/to an external tank, is very hard on the pump and in my case with the miles on the transmission it was too much, and even if fewer miles, it subjects the pump to unnecessary stress. He said it wasn't necessary to do a flush, the fluid and filter change is sufficient.

[Pntyrmvr]

What is the pump doing its entire life if not pumping fluid around? An external tank is the same thing as the rad and/or auxiliary cooler. That reasoning defies logic.


"Talk is cheap. Whiskey costs money."

[marret]

Well, that may be, but can you explain the pump failure soon after?

I believe the process puts extra stress on the pump. With a high mileage transmission... There are likely factors impacting this and I don't know what they are. Maybe the amount of fluid in a short time, how it was done, etc., I don't know. I do know the pump failed and the trans required a rebuild within a very short time after.

Either way it doesn't matter to me, a mechanic who rebuilt a lot of transmissions told me it was not necessary and did not recommend the procedure. That coupled with my failure was enough for me. Others may disagree and that is fine.

At the end of the day, keeping the transmission serviced with clean fluid and filter is important.

[Pntyrmvr]

The extra crap loosened by flushing the trans would certainly stress the pump. Also running it dry during the process could be contributory if it occurred.

Trans life is limited. How long will the one in there last now? Even if flushed regularly. I'd be happy with 200K on a trans.


"Talk is cheap. Whiskey costs money."

[marret]

Yep. 200k is reasonable I think, but more is possible.

[carringb]

A "transmission flush" usually implies a machines which uses its own pump to pressurize the transmission. These are the ones that can cause damage. A "transmission exchange" machine uses the transmission's own pump, should not cause damage, and is recommended by Ford.

The last time I dropped my pan was at ~170,000 miles. The "filter" within is really just a screen to capture large debris. And external filter provides better filtering, enough so that Ford spec's one after a rebuilt or replacement. Since adding a Magnefine external filter, I just swap that out instead of the dropping the pan, since it's way less messy and does a better job. Currently have 433,000 miles and the transmission still shifts like-new.

[E-rex]

Originally Posted by Pntyrmvr

...running it dry during the process could be contributory if it occurred.

The recommended process as I understand it is to flush it out in several 'batches' of 5-6 qts per, where you dump some, then replenish, then dump more, replenish again (etc). Being lazy and trying to push out more and do it in one shot could have the pump sucking air, which I could see stressing the pump, perhaps to the point of damaging it. All this does make me wonder how many qts I am down if the fluid is not even registering on the dipstick. Rex is not on the road yet (should be in a month or so), so I was just going to do the fluid change before registering (or right after), rather than wasting fluid right now topping it off.

Barring running the tranny too low on fluid, I would tend to agree with the logic that the pump is moving fluid within normal the operating pressure range, but of course, that it my opinion (as opposed to a proven fact).

[boywonder]

Originally Posted by E-rex

Did you change the filter or drop the pan?

Nope....but probably will next time.....

[KilrPilr]

When I had my 2000 F150 I used to take it regularly into a quick lube place for trans fluid exchanges. Usually about ever 30k. They used the transmission pump method and they had 2 clear glass tanks. One had fresh fluid in it and the other was empty and as it filled you could see the huge contrast in color of the fluid until the clean fluid tank was just about empty then you would see clearer fluid coming in the dirty tank. I always noticed an improvement when I left there. After about every 2-3 fluid exchanges, I would get the filter changed. I totally recommend it.

My Father in-law is a mechanic for the last hun years and he wont go near the pressurized exchangers. He told me one time after an exchange with one of those machines (and the use of cleaner additives during the flush), the filter got so clogged with crap the pressure from the machine crumpled the filter up into a ball. I guess they figured that out after the vehicle wouldn't move.

Anyways the truck had 414,000 km or so when I got rid of it 5 years ago , (Still see it driving around) and never had a tranny problem. In fact, when I felt anything weird about the shifting or sluggishness of the shift, I knew it was time and when it came out from the exchange the problems wouldn't be there anymore.