928saregreat

If no previous maintenance record on the automatic is known and the fluid is burnt smelling and discolored I would never recommend using a T-Tech "flush" machine on the transmission. Since these cars we're so fond of were built before this technology existed (with the exception of the GTS perhaps) just do the recommended service, drop the pan, clean it, change the gasket/filter, replace the fluid in the pan ONLY. I've seen many old transmissions "shocked" into slippage by the cleaning power of 100% fresh transmission fluid. This is no myth. I see it everyday! If you don't know the history, DON'T FLUSH IT. Just by doing the recommended maintenance you're gonna get a pretty good idea of the condition by the amount of metal hanging off the magnets in the pan.

Mark

SteveG

It would be nice to know Outlier's mileage and get a feel from the rest of you as to any correlation of mileage on the oxidization process. Or is there none?

0utlier

I've got 114,000 miles on the car. The car seems to have been well taken care of by the PO. There are pics of it at https://rennlist.com/forums/928-forum/278889-new-to-rennlist-new-928-owner-and-i-brought-pictures.html. I've got probably close to $10k in receipts from the PO for the last 6 years or so. He seemed to take care of the car when anything came up. I have no receipts for the first 10 years of life though.

sstrickstein

Having been down this road myself about a year ago I will add my experience. The problem with FLUSHING an unknown transmission is that as the fluid wears it uses up its additive package and gains grit and wear particles from the transmission. This process makes a worn unit last a little longer but once the old gritty fluid is removed and the transmission cleansed the old material which was actually helping the worn unit operate is gone and new fluid with additive package in its place. The worn clutch plates soon succumb to the new fluid and the transmission dies soon after.

If however the fluid is changed regularly as the factory intended the life expectancy of the unit is much longer. The proper procedure as described in the Factory manual is to drop the pan, and replace the filter, and if there is signs of burnt fluid or clutch materials in the pan, blow out the trans lines and cooler completely before filling. The problem is that if the trans pan is full of crap, chances are the cooler will be clogged with it as well. When in doubt remove the radiator and have it properly cleaned. Once this is all done, also drain the torque converter. There are a lot of information as to the proper procedure to refill and how much at a time.

I am not an expert, just an owner that did it the wrong way and killed his old transmission. And if someone tells you that a burned out transmission is easily repaired.... RUN. These transmissions are complex and take an experienced hand to get right. I did it the wrong way and am now on transmission number 2.

Transmission service-- changing fluids and filters is never a bad thing. Pressure flushing a worn unit is. I believe Greg once said on this forum, that these transmissions are all either in need of a rebuild or getting close. He is right.

Don't wait until your transmission is stuck in limp mode or slipping and making that OH MY GOD WHAT IS THAT SMELL!! When that happens its too late.

Oh by the way on a lift with proper tools it takes about 3 1/2 hours to remove the transmission from an 84. Ive never done it on jack stands but it cant be fun.

dr bob

So far... (knock on wood) my pessimistic 'change ATF and filter every couple years' program hasn't resulted in anything bad. The discussion about depending on the grit and varnish to maintain seals and clutch plate action is, um, an old wives' tale. While accumulated 'varnish' might seem to be doing some of this, the trans is already well on its way to the tranny graveyard if this is truly happening. Just like taking a biopsy of a tumor causes cancer, right... As mentioned by others, changing stinky fluid isn't the problem; the stinky fluid itself is the problem.

For many who don't put a lot of miles on their cars, going to a calendar-based schedule for fluid changes is a good idea in my opinion. It's not a big inconvenience to add ATF and steering system flushes to the biannual coolant change ritual, really. In the giant scheme of things, the filter and gasket kit isn't expensive, the fluid itself isn't at all expensive. The only inconvenience, if there is one, is sitting with the hand pump getting new fluid back in. And there's a certain therapeutic value to that I think.

Randy V

I agree with Dr. Bob.

This urban car guy legend is alive and well in many other marque communities, especially BMW and Mercedes.

It is completely counter logic yet it persists for some reason.

sstrickstein

As I mentioned. It is not the regular service that kills the transmission. It is the lack of regular service then sudden flush that does. Keep doing what your doing.

928NOOBIE

OMG....Karborian Belts make EVERYONE look fat....in the name of Mayonnaise have a heart man...

Randy V

And that logic is exactly what we're saying is misplaced urban legend.

Try and explain it in technical terms that makes sense.

The proposition is that old dirty trans fluid is better for aging transmissions than new clean fluid.

This is Bizarro World thinking.

polecat702

When I read some of these old threads, it reminds me of how much I miss my friend, and hillbilly buddy Greg Nettles! Hope there's plenty of cold Coors beer for ya Greg!!!!

dr bob

Redneck car maintenance logic:

"I never change the oil in my car. I just add some when it starts to make a louder clicking noise when I start it. The thick sludge keeps the pan gasket from leaking. A friend went over fifty thousand miles before he changed the oil. Soon after, the pan gasket started to leak, and then it started make even bigger noises. His mechanic said it was a rod bearing, whatever that is. I think that the new oil flushed the sludge out of the bearing, and that's what was holding it all together. That's why I'm never changing it, at least until it gets to just a little under 100k on it. Then when the engine fails, I'll get a whole new one under warranty. So I can go another 100k on the new engine, and still never have to pay for another oil change. I win!"


Someone can easily translate this into "automatic transmission"-speak.

Tazzieman

The Royal Flush
Amazing how many believed this!

sstrickstein

In technical terms as a automatic transmission wears the clutch material wears thin and is transmitted both into the fluid and filter. The idea is that part of the clutch material becomes suspended in the fluid and at the same time the fluids self cleaning additive package wears out. SO you have fluid that has "grit" suspended in it and clutch packs that are only working still because of that same grit. When the fluid is replaced the grit is replaced by stronger new fluid which "cleans" the worn clutch packs and in a short time wears out. Now This idea is not a urban legend, it is a proven fact. But we are not talking about transmissions with low miles or that have had fluid changed regular. We are talking about the 30 year old transmission which probably has not had a fluid change in a decade or two and has 120k or more miles. Greg's comments about this goes further. A 30 year old transmission has worn out seals and o-rings too. They leak and make the unit malfunction. Before I rebuilt my transmission it was functioning but rather clunky. I put trans-X in it and the function of the unit did get better for a while. Then what ever clutch I had left gave up and with it internal hard parts began to wear. In the end I wound up throwing that transmission out and starting over with a known good core. If I had stopped when it was first acting out, That might not be needed. SO believe what you will. Better yet read some of Greg's posts on automatic transmissions. He knows his stuff. If he wont sell one of the NEW OLD STOCK units he bought without first going through them... what makes anyone think any of our 30 year old units don't need work.

sstrickstein

Here is the link to my thread from last year about my rebuild craziness. I still cant believe I pulled that transmission 3 times. Madness. The message here is don't be careless with these transmissions. They are complex. Take a look at the pictures I posted. You will see the results of a burned out transmission.


https://rennlist.com/forums/928-foru...n-rebuild.html

Randy V

Here's that engine Dr. Bob speaks of - I can see why a transmission in a similar state would not benefit from a fluid change.