Trans Flush??

[explorerguy27]

I have a 98 EX, V8, AWD. I was wondering what I should do to service the trans? I have had for about 2 years now and think it's time to do it. Any suggestions? Thanks in advance.

 

[Glacier991]

How many miles on the trans? Ever had the fluid changed? How does the fluid look? How does it perform?

 

[aldive]

I am a believer in flushing the tranny and in using synthetic ATF.

Good luck ........

 

[H.A.L.O.]

i do mine every 30,000 because i drive the hell out of it

 

[BigOne]

Well, I'm not a big fan of trans flushes.

I do the regular maintainance of changing fluid and filter as per spec. The only two times I've ever had a trans "flush" done the tranmission has failed within 25,000 kilometers thereafter.

One, the most recent, was my Ex which was flushed at 165,000 kilometers and had a fluid and filter change as well. Started leaking at the rear seal at 177,000 kilometers while on a highway run and burned up the clutches pretty bad. Total repair about $2000 CDN.

The other one was on my Mother's 83 Marquis. Trans flushed at 150,000 kilometers as per dealer recommendation (in her 80's she goes to the dealer too much). Trans seal (I think front) went out at 169,000 km.

So, maybe a trans flush is a good thing if you do it regularly but if you have some miles on it I feel maybe the fluid and filter is enough of a shock to it's system.

 

[aldive]

Please explain why you feel that a tranny flush caused the problems mentioned above.

Also why do you think a tranny flush is potentially harmful.

All that you are doing is letting the tranny pump out old fluid while adding new.

 

[ExplorerDMB]

Aldives right. There isn't any extra "pressure" being injected into the system. The machine that most shops use will usually run anywhere from 20-50psi, but that is from the transmission itself, not the machine. The machine basically catches the old fluid which pushes the new fluid in. Flushes are safe and very good!

That is similar to the machine we use, but they are great and easy to set up (usually).

-Drew

 

[BigOne]

As I say, my experience has been that the two times I've had flushes I've had failures following. Why? I'm not an automatic transmission expert so I don't know why.

I've been turning wrenches for 30 years, but don't touch automatics myself.

Both of the failures have been seal problems. My speculation is that the flush may have removed varnish and deposits from around the seal area, possibly on the shaft that then allowed a leak to start.

Not knowing what service, if any, either of these vehicles had before acquiring them, these may well have been the first fluid/filter/flushes that had ever happened on them. I would agree, that if one has a vehicle from the time it is new, the flush idea would be a good one to ensure complete cleaning. As most of us know dirt is a major enemy of the automatic transmission.

Many of us also know that new transmission fluid is actually quite a cleaning agent. It can and does remove deposits that have accumulated over time. There are also custom rifle barrel cleaning solutions that are based on automatic transmission fluid due to it's ability to remove deposits and fouling.

When a seal is old, it is not as flexible as when new. In the case of the older transmissions the removal of deposits may have caused microscopic seepage that the harder seal was not able to control, thus leading to increasing leakage and eventual failure.

So, from my experience, I don't feel a flush is always a good thing, particularly on a transmission that is upwards of 150,000 kilometers (approx 100,000mi).

 

[Rhett]

As I say, my experience has been that the two times I've had flushes I've had failures following. Why? I'm not an automatic transmission expert so I don't know why.

how many times did you flush it? Just once?

In my experience there are TWO reasons why the transmissions failed on you after flushing:
1) the method used to do the flush subjected the seals to extraordinary pressures, or
2) the transmission in question was only flushed that one time, not AGAIN in a week or two.

re: #1, The way I do it, the transmission never knows it's being flushed, because as a quart goes out, a quart goes in via the filler neck, no out-of-spec pressures subjected to it at all.

And re: #2 above, if you just flush it once, you're asking for trouble...the new fluid has lots of detergent properties, and will knock loose lots of gunk and varnish, and likely the old filter is ready to be replaced too. So a second flush, after a week or so, is sometimes wise on a transmission that's never had it done before.

 

[Glacier991]

The flush or no flush debate is an ongoing one. Big One does a good job of articulating a not wholly unheard of complaint (eg. I flushed it and shortly after had a failure) and others likewise do a good job explaining that the equipment does not pressurize the system, and hence a complaint which in some fashion appears to casts blame on the process seems poorly founded. In response Big One postulates some interesting ideas for everyone's consideration which might explain his experiences. I would add that all too often the "flushed it and it failed" stories are not related as a personal experience but rather as a "I heard from my Uncle Joe that he had a friend who's brother, etc etc.." Big One has related his own experiences and I think that is worthy of note as we ponder this.

Is there a definitive answer to this age old debate? I doubt one exists which everyone would accept as definitive. I think the one thing everyone would agree on is that regular fluid changes (30-50,000 miles) are one way to help extend the life of your transmission. If you come into possession of a vehicle with an automatic transmission where the fluid has not been changed (maybe ever!) and it has A LOT of miles on it... well... you may have some decisions to make.

Me? I'd accept there there may be some empirical value in what Big One has said, I'd weight that against running the trannie on fluid which probably has very poor operational characteristics. I mean if the choice came down to change or no, I'd opt to change. If I was really worried I might do a "pan drop change" - and change only a portion of the fluid by doing so. Sort of the "worst of both worlds".

I'm always interested in this debate, especially where we consider evidence and postulate causes.

 

[spindlecone]

G
Do you have any thoughts of possible benifits (or none) of using an oversize oilpan, such as a PML (finned aluminum) my temps never exceed 150 degs, even on the hottest valley days.
I also drain out 7 qts of tranny fluid every 5k miles and replace with Merc V, (overkill or maybe benificial?)

 

[BigOne]

how many times did you flush it? Just once?

Both were done at tranmission shops, different ones. They had the vehicles for the day and did the flush. No mention of how much fluid was flushed through. No mention of how long it was on the machine recirculating fluid through a filter. No "bring it back in a week to do it again". No mention of anything else.

I have not experienced a similar failure on the old drop the pan and change the fluid/filter. I've done literally hundreds of these myself with no ill effects.

Both of the flushes were done on transmissions that had relatively high mileage with no known history of servicing (approx 100,000mi). Fluid on the stick appeared dark, but was not burned nor did it smell at all wrong. No sign of water contamination or anything else was evident.

So anyways, I'm hoping to have a transmission in it now, that with proper care can last a good long time. When the rebuild was done, I had them do it all, no skimping on bands that looked "ok" or the like.

 

[Glacier991]

Spindlecone.... my take on deeper cast pans is that they a) provide a greater storage area for fluid, so you might extend the time between changes as a result; b) provide what would seem like an increased cooling surface - but I have little evidence to suggest that this is significant, at all; c) in high HP applications might provide a little more case integrity - not that I have much experience with high HP case failures; d) often provide both a thickness and place to drill for temp senders, and e) look sexy as hell.

Also 7 qts every 5000 miles is way overkill.... but at least yer not hurting anything. At 15-20,000 miles you may have a more viable idea.

 

[explorerguy27]

Sorry I haven't been here, I was out of town. I was just trying to think of ways to extend the life of my trans. The EX has 137k on it, and I do pull occasionally. The trailer I pull wieghs on average 4500 to 5000 lbs. My EX is equipped with the factory towing package including the extra trans cooler. I don't know when the last time it was serviced. I bought it with 105k on it and I haven't done it yet. Thanks for any advice. Rob

 

[aldive]

A few other things to help prolong the tranny's life are:

Another cooler in line with the one you have
An external tranny filter
Possibly a tranny temp gauge

Good luck ...

 

[adarkang]

Well I was on rangerforum and someone mentioned when doing a transmission flush to not let the torque converter go dry. The two cooler lines coming off the transmission are disconnected and 1 quart is drained and then filled through dipstick, will this run the torque converter dry? Nothing is hooked up to the return line when doing this sort of flush, or am I supposed to hook up that other line to something else?

Oh yeah I also decided I am going to do a flush since I changed the filter and pan fluid 26,000 miles ago. I dont think it is too necessary to change the filter again.

 

[adarkang]

anyone???

 

[Glacier991]

I am unaare of any reason for the fear of "running the convertor dry". Ex. on the 4R70W the convertor has a drain plug! If surely is "dry" when it is drained. I think someone has poor info and is making too much of it. I change it with the engine running pumping out fluid as I add it to the fill tube.

Relax. If you want to do it a quart at a time you are taking extreme care against a non-existent problem., but no harm.

 

[adarkang]

Thank you! That is what I wanted to hear.

 

[holter95]

leveraging facts and myths...

Here's a sticky that describes some info about trans flushes.

http://www.explorerforum.com/forums/showthread.php?t=161337&highlight=trans+fluid+flush

I would tend to agree... a flush can be good or bad. I think if done regularly from when new, a flush could be advantageous to keeping the system clean and the fluid healthy. However, with older transmissions that have seen a lot of use, or haven't had frequent fluid changes or flushes, to a certain degree they are happy running as they are. A fluid flush, and the detergent capability of the new fluid or any additive can help dislodge sediment or varnish, which otherwise would stay happily in place. In low-tolerance valves, these particles could cause problems.

From personal experience - I did a fluid flush on my own (the at-home method described in several other posts). It seemed to work well, but I saw trans failure about 25K miles later. Was it to blame? Maybe, maybe not. The failure mode was a combination of a sticking 1-2 shift solenoid as well as a couple of broken bands. (I'm no trans expert by any means)... and the trans had about 130K miles on it... in my experience, about the max for the 4R55E without meticulous maintenance. I had done standard filter/pan drops before, so I was only getting about 1/3 of the fluid.

I'm going to roll the dice with a flush this week... the first on the new trans after about 25K miles. Hopefully it hasn't had a lot of time to gum up, and it should treat it well. Plus, I just finished doing about 1000 miles of heavy towing this weekend, and the fluid is looking pretty dark after that. Crossing my fingers that all goes well, and that my logic works that this trans should be able to handle a flush, since it's reasonably new.

WRT the torque converter - I too have heard if you do the flush yourself, it is imperative to maintain the fluid level as much as possible - you do NOT want to run it dry. That's how the pump systems work: fluid in = fluid out, so you maintain correct fluid pressure.

My personal recommendation? If you've got 80K or more on a trans, and have maintained it only minimally, you may want to just do a pan-drop and replace some of the fluid... maybe do it a few times successively over the course of 5000 miles to kind of do a "slow" flush, which won't shock the system so bad if you have a lot of mileage gunk built up in it. But that's just my $.02.