Low gear appears to be gone..

allbrandauto wrote:
you are doing the same thing a flush machine does that's why they should call it a exchange machine if your not putting chemicals in trans. before you do it all your doing is exchanging all the fluid

I assume you are dropping the pan and changing the all-important filter within the standard service/charge then? In other words, are you saying you are price competitive with professional transmission repair shops that always drop the pan, absolutely change the filter, but usually don't bother pumping the converter if the prior tranny oil is in anywhere near normal condition? Yes, some serviceable old oil remains in this case. Some torque converters have drain plugs and are manually drained sans machine. All legitimate pro-shops do flush or replace the entire converter after a major failure, and I am a big believer in replacement, especially on lock-up units.

One should keep in mind that some trannies have been so neglected that the filter is so plugged with wear debris, it is thee primary source of shift problems. In other words, in this case, one could foolishly put the old oil back in, yet just adding the new filter would temporarily solve shift issues. The old '80's Chrysler Minivans were notorious for plugged filter problems. Of course it always made sense to replace the old oil at the same time. After such service, I always recommended that the owner definately mind the next recommended service interval, or no more than 40k miles... if they were not towing... and some were.

It is the strangest thing that many people that will give their autos reasonable engine oil changes, yet do not follow recommended service intervals for transmission fluid, or 3-year green coolant changeouts (5-years, orange Dex-Cool or extended life). Pertaining to coolant changeouts, many engines have needlessly corroded to an interior leak that allows coolant into the crankcase and destroys the otherwise well-oiled engine. And if the coolant interval is followed, there is again no compelling reason to remove all traces of the original coolant. If one wants to save $, partially draining and adding a new major portion is acceptable to save unnecessary labor and far superior to nothing.

And then there often a neglected need for new brake fluid, differential and transfer case refill under some conditions.

Wes
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you are doing the same thing a flush machine does that's why they should call it a exchange machine if your not putting chemicals in trans. before you do it all your doing is exchanging all the fluid

Chum lee wrote:
Although I am not a Master Tech by trade (I am an engineer) I have owned and changed the ATF in many cars/trucks. Virtually EVERY factory service manual I've read that recommends one says when changing the ATF to DROP THE PAN AND CLEAN OUT THE DEBRIS on the bottom, on the magnet (if there is one) and clean/replace the filter. That is far more important than flushing every last drop of used ATF out of the system.

I don't care how many times you flush the fluid, the debris on the bottom of the pan stays there until someone physically drops the pan and removes it. It simply doesn't come out with flushing alone.

Think of a torque converter as a 10 hp centrifugal ATF filter. Have you ever looked at the debris inside a torque converter when a rebuild shop cuts the shell apart? Its the same stuff that is on the bottom of the pan. ATF is different from engine oil in that it has few if any added dispersants mixed in the formula. The engineers WANT the particulates to drop out of the fluid in ATF whereas with engine oil not necessarily so. Also, ATF hopefully isn't subject to contamination from combustion byproducts whereas engine oil is.

To the OP, hopefully an ATF flush will solve your problem but I wouldn't bet on it. You've been given some good diagnostic options by others. Good luck.

Chum lee

I'm paranoid about flushing transmissions and especially if they're old with miles. Had a jeep for 19yrs and never changed the fluid, as with all my other vehicles. With the RV here, it's had a rough life both in the Rockies and Appalachia, so what I've done is to drain out all I can with the plug drain, run it for awhile, then do it all over again. I figure with about two or three of these procedures, I have about 85% of fresh fluid. Too lazy and cautious about pulling the pan and doing anything further. So far so good at over 90K miles and hate arguing with success, so.....

Although I am not a Master Tech by trade (I am an engineer) I have owned and changed the ATF in many cars/trucks. Virtually EVERY factory service manual I've read that recommends one says when changing the ATF to DROP THE PAN AND CLEAN OUT THE DEBRIS on the bottom, on the magnet (if there is one) and clean/replace the filter. That is far more important than flushing every last drop of used ATF out of the system.

I don't care how many times you flush the fluid, the debris on the bottom of the pan stays there until someone physically drops the pan and removes it. It simply doesn't come out with flushing alone.

Think of a torque converter as a 10 hp centrifugal ATF filter. Have you ever looked at the debris inside a torque converter when a rebuild shop cuts the shell apart? Its the same stuff that is on the bottom of the pan. ATF is different from engine oil in that it has few if any added dispersants mixed in the formula. The engineers WANT the particulates to drop out of the fluid in ATF whereas with engine oil not necessarily so. Also, ATF hopefully isn't subject to contamination from combustion byproducts whereas engine oil is.

To the OP, hopefully an ATF flush will solve your problem but I wouldn't bet on it. You've been given some good diagnostic options by others. Good luck.

Chum lee

wolfe10 wrote:
There are view points on both sides of the "flush" discussion.

I know in writing, Allison recommends AGAINST flushing. On cars/light trucks, I often dropped the pan, changed filter if present and filled. Then took loose the return line from cooler and idled engine until clean fluid came out.

Lots of ways to do it with good reasoning behind each.

This is what I do also. I dip a white paper towel in clean trans fluid and keep checking the fluid coming out until it looks like the clean stuff on the paper towel. The first time I did this (30k miles)I was shocked at the stuff in the bottom of the pan and on the magnet. At 60 k miles there was still stuff on the magnet but a lot less. At 90 k was about the same as 60 k. So if you have more than 30 k miles and have climbed a few long hills and got into the red (or the PO did) a fluid chg could help your shifting problem.

To flush or not to flush. That is the question. Whether tis nobler in the bowels of Winnebago to suffer the slings and arrows of outrageous scummy fluid. As for me and my house I see flushing as a more thorough approach with the various feedbacks. **** you dirty fluid. Be gone henceforth. Your end is the dung heap....

I did invest in a flush machine about 15 years ago can do a much better job for my customers and my own cars but they should call it a transfusion machine

There are view points on both sides of the "flush" discussion.

I know in writing, Allison recommends AGAINST flushing. On cars/light trucks, I often dropped the pan, changed filter if present and filled. Then took loose the return line from cooler and idled engine until clean fluid came out.

Lots of ways to do it with good reasoning behind each.

allbrandauto wrote:
as a shop owner and a master teck. I highly disagree with you about the the so called flush scam machine so you would rather drop the pan and fill the trans. with new fluid and mixing it with all the old fluid in torque converter what sence does that make when you can exchange it all your thinking is old school technaligy has caught up

Invest in a flushing machine did you??

Thank you allbrandauto for chiming in. I appreciate help from those in the biz. Any hints you have to offer are greatly appreciated...