Flushing Your Transmission?

[craigwatanabe]

Re: Is flushing your transmission a good thing?

I disagree. See my post above.

Somehow I knew you were gonna disagree but damn so fast?

To me if your tranny is old and is looking like it's slipping badly to the point of overhaul or replacement, you may as well try the tranny flush. The worst thing that can happen is basically the rebuild or replacement which is what one would have done if not a flush.

[GeckoGeek]

Re: Is flushing your transmission a good thing?

To me if your tranny is old and is looking like it's slipping badly to the point of overhaul or replacement, you may as well try the tranny flush.

Not much to loose at that point. But if it's working fine and you're just worried about it.....

Just change the fluid and leave it at that.

[Frankie's Market]

Re: Is flushing your transmission a good thing?

Changing the fluid is a good thing. Maybe even techniques that help get all the fluid changed.

But I wouldn't use a chemical flush. It would be an especially bad idea to do it to an older transmission where the varnish may be what's holding things together. I think there's been enough cases of transmission failing shortly after a flush that many mechanics do not recommend it.

To a tranny that has been neglected not been regularly serviced and properly maintained, I agree with you. Once the tranny fluid turns super black and filled with sediment, you might very well be better off with not doing a flush and just milking whatever miles you're going to get out of it. If you're lucky fortunate like a couple of people on this thread, you might wring out considerable mileage out of a transmission that is basically shot.

But on a brand new car, I couldn't disagree with you more. Read what Craig said in his first post. A simple draining of the AT will leave a lot of the old fluid in. The new fluid that you pour in will only get contaminated by the remnants of the old degraded fluid, along with all the metal particles and sludge. I don't care how many times you change your fluid. By the time you get to 100K miles on your car and you haven't performed a flush, the fluid on your tranny dipstick is going to be very dark. And if it was properly maintained, it shouldn't be that way.

[GeckoGeek]

Re: Is flushing your transmission a good thing?

We need to define what a "flush" is. To me a "flush" is when you put in a special fluid to clean things. I don't have a problem with using a pump to get all of the fluid out of the torque converter. I do have a problem with pumping solvents though your transmission.

[oceanpacific]

Re: Is flushing your transmission a good thing?

A simple drain and re-fill of the transmission fluid could leave 40% or more of the old fluid in.

In my case, I purchased my car as a lease return in Oct. 2000 with 36K miles on the clock. While not a "brand-new" vehicle, the transmission has been flushed on a regular basis (24-month cycle) since then. At the time, I was shown service records indicating that a transmission flush had been performed a few months earlier in August 2000 - I have dealt with that dealership before and have no reason to doubt their word.

So, at 143K miles, my vehicle is running smoothly. To me, the $100-120 cost for the flush has been money well-spent, not the scheming of the service department to increase my bill. Besides, it's been a legitimate tax write-off for me, anyway.

Those who neglect regular servicing of the transmission (or entire vehicle, for that matter) are penny-wise and pound-foolish.

[Konaguy]

Re: Is flushing your transmission a good thing?

I have a 2005 Ford Ranger which I just took in for its 30,000 mile servicing. Among the things that were checked was the automatic transmission fluid.
According to the mechanic, the fluid was still red. So it didn't need to be flushed. He said it likely wouldn't need to be replaced until 60K miles.

[68-eldo]

Re: Is flushing your transmission a good thing?

My experience with my ’68 Eldorado and a number of other cars is that a transmission flush is a waste of money. The Eldo has over 300,000 miles on it and it has never been flushed and it still runs well. It has had a number of fluid and filter changes. Nobody has said anything in this thread about changing the filter but that is as important as a fluid change.

I disagree that transmission fluid is hydroscopic. I’ve never heard that before. Brake fluid is hydroscopic and it must be changed every few years especially if you have disc brakes.

Tell me what you think the transmission fluid gets contaminated with. As far as I know only the dust from the clutch plates and a few metal filings ever get into the transmission fluid. I’ve pulled a few pans and all I’ve seen is the dust and a few metal filings.

I also think we need to define what a “flush” is. A true flush is when they disconnect the fluid line to the radiator and connect it to the flushing machine. The machine pumps the old fluid out and the new fluid in. If they just stick a hose down the dipstick tube and pump the fluid out them they are not doing any more than a simple fluid change. What’s worse is if they do not take off the pan they are not changing the filter.

[oceanpacific]

Re: Is flushing your transmission a good thing?

Well, it's your cars for you and my money for me. To each his own ........

[craigwatanabe]

Re: Is flushing your transmission a good thing?

My experience with my ’68 Eldorado and a number of other cars is that a transmission flush is a waste of money. The Eldo has over 300,000 miles on it and it has never been flushed and it still runs well. It has had a number of fluid and filter changes. Nobody has said anything in this thread about changing the filter but that is as important as a fluid change.

I disagree that transmission fluid is hydroscopic. I’ve never heard that before. Brake fluid is hydroscopic and it must be changed every few years especially if you have disc brakes.

Tell me what you think the transmission fluid gets contaminated with. As far as I know only the dust from the clutch plates and a few metal filings ever get into the transmission fluid. I’ve pulled a few pans and all I’ve seen is the dust and a few metal filings.

I also think we need to define what a “flush” is. A true flush is when they disconnect the fluid line to the radiator and connect it to the flushing machine. The machine pumps the old fluid out and the new fluid in. If they just stick a hose down the dipstick tube and pump the fluid out them they are not doing any more than a simple fluid change. What’s worse is if they do not take off the pan they are not changing the filter.

Hydraulic fluid by nature is hydroscopic because it has to take away moisture to ensure positive differential pressure when pumping under pressure.

When you use the transmission cooler's in/out tubes to do a flush you are basically sucking out the old tranny fluid that cannot be drained out.

And it is pretty much assumed that for any kind of fluid change you change the filter. That's pretty much a given.

One can get anal about it and do several cycles of tranny flushing to ensure all particulates are removed to a reasonable level but for practical purposes a single flush will take out most contaminates.

When I do oil changes on my cars I typically will run some cheap oil after draining the old oil for about a hundred miles then drain that and put the good stuff in. It won't take out everything but it will take out more than a simple draining of oil.

Older cars such as your 68-Eldorado were built like tanks and they will go a long way before major overhauling is required. Here in Hawaii with a lot of stop and go traffic plus the varying terrain and elevation, wear on automatic transmissions can be more intense than mainland highway driving. Plus with our humid weather transmission fluid does take in more moisture than less humid environments.

If you see a few metal filings in your tranny filter pan then you got some wear going on inside that transmission of yours. These metal particulates can become lodged in the shift valves that modulate the shifting action based on throttle pressure. If the shift valves get stuck the tranny won't shift and you get stuck in that particular gear.

This is why changing your tranny fluid regularly is important, before major wear results in a major overhaul.

[68-eldo]

Re: Is flushing your transmission a good thing?

Because I sense we have a different definition of the word hydroscopic I entered the word into the Merriam-Webster online dictionary. This is what I got:

The word you've entered isn't in the dictionary. Click on a spelling suggestion below or try again using the search bar above.
Suggestions for hydroscopic:
1. hygroscopic 2. hydrosolic
3. hydrochloric 4. hydrophobic
5. hydrospheric 6. hydropathic
7. hydrospaces 8. hydrologic
9. hydrospace 10. hydrocolloid
11. hydrological 12. hydrochloride
13. hydrocolloids 14. hydrochlorides
15. hydrazoic acid 16. hydropathies
17. hydrocortisone 18. hydrocephaly
19. hydraulically 20. hydrologist
21. hydrologies

So that word is not a word. I selected the first option which is Hygroscopic and is the word I assumed was meant to be used. And I got:

hygroscopic

Main Entry: hy·gro·scop·ic
Pronunciation: \ˌhī-grə-ˈskä-pik\
Function: adjective
Etymology: hygroscope, an instrument showing changes in humidity + 1-ic; from the use of such materials in the hygroscope
Date: 1790
1 : readily taking up and retaining moisture
2 : taken up and retained under some conditions of humidity and temperature <hygroscopic water in clay>
— hy·gro·scop·ic·i·ty \-(ˌ)skä-ˈpi-sə-tē\ noun

Hydraulic fluid is normally a petroleum based fluid and will not absorb water. Normally in an engine or transmission any water that gets in is removed by heat. That’s one reason why short trips are not good for a car.

As to the metal filings small metal filings are normal as the bearings in a transmission are not ball or roller but bronze bushing type that do wear and produce a fine metal dust. This is normal. The filter is there to prevent that dust from getting into the valves and other components. There is a big difference from the normal shiny metal dust and the metal flakes that result from a major problem.

[Frankie's Market]

Re: Is flushing your transmission a good thing?

When I do oil changes on my cars I typically will run some cheap oil after draining the old oil for about a hundred miles then drain that and put the good stuff in. It won't take out everything but it will take out more than a simple draining of oil.

I used to do that too in the old days when there were only petroleum-based motor oils on the market. But if you use a good quality synthetic, there's no need to do all that extra work.

But that's just my opinion. And I mean no offense to anyone in stating it.

Older cars such as your 68-Eldorado were built like tanks and they will go a long way before major overhauling is required. Here in Hawaii with a lot of stop and go traffic plus the varying terrain and elevation, wear on automatic transmissions can be more intense than mainland highway driving. Plus with our humid weather transmission fluid does take in more moisture than less humid environments.

If you see a few metal filings in your tranny filter pan then you got some wear going on inside that transmission of yours. These metal particulates can become lodged in the shift valves that modulate the shifting action based on throttle pressure. If the shift valves get stuck the tranny won't shift and you get stuck in that particular gear.

This is why changing your tranny fluid regularly is important, before major wear results in a major overhaul.

Exactly. That's one of those problems about someone asking a question like this in an open forum. You have the people who will give the type of answers that are recommended for most cars. And then you have the handful who will say, "NO NEED! My car has gone X number of years and X number of miles without doing a flush," when the reality is that they were somehow fortunate enough to get away with not performing what is a vital maintenance chore for most other cars. Other people reading this (and this would include the lurkers who only read and don't post in this thread) might heed advice that is wrong for their car and end up paying several thousand dollars at the transmission shop, just to get their cars on the road again. As OP alluded to earlier about being "pennywise and pound foolish," listen to him, folks! You can either spend the $100-200 now on a flush,..... or take the chance that you may end up paying thousands at the tranny shop later. It's up to you.

[craigwatanabe]

Re: Is flushing your transmission a good thing?

I used to do that too in the old days when there were only petroleum-based motor oils on the market. But if you use a good quality synthetic, there's no need to do all that extra work.

But that's just my opinion. And I mean no offense to anyone in stating it.



Exactly. That's one of those problems about someone asking a question like this in an open forum. You have the people who will give the type of answers that are recommended for most cars. And then you have the handful who will say, "NO NEED! My car has gone X number of years and X number of miles without doing a flush," when the reality is that they were somehow fortunate enough to get away with not performing what is a vital maintenance chore for most other cars. Other people reading this (and this would include the lurkers who only read and don't post in this thread) might heed advice that is wrong for their car and end up paying several thousand dollars at the transmission shop, just to get their cars on the road again. As OP alluded to earlier about being "pennywise and pound foolish," listen to him, folks! You can either spend the $100-200 now on a flush,..... or take the chance that you may end up paying thousands at the tranny shop later. It's up to you.

yeah...what FM said!

[68-eldo]

Re: Is flushing your transmission a good thing?

I really don’t think the technology in transmissions has gone backwards, nor do I think the manufactures are building transmissions with lower quality.

But it is your money and spending it this way keeps mechanics employed.

[oceanpacific]

Re: Is flushing your transmission a good thing?

Which brings to mind that commercial from decades ago aimed at those who fail to do car maintenance:

YOU CAN PAY ME NOW, OR PAY ME LATER .......

[68-eldo]

Re: Is flushing your transmission a good thing?

So let me get this straight. A proper transmission flush includes a filter change. To change the filter you have to remove the pan. So the mechanic disconnects the transmission line going to the radiator and while the engine is running pumps the old fluid out and the new fluid in. Then he removes the pan (dumping the new fluid just put in) changes the filter and refills with more new fluid?

Seems like a waste to me.

I just read the recommended maintenance schedule for the wife’s ’02 Buick and there is no factory recommended transmission flush. Why am I not surprised? Or is 2002 way back in the olden days when cars were built like tanks?

Does the Owner’s manual for your car recommend a transmission flush?