Home made Trani Flush Machine

[Tim Reynolds]

OK, I know I'm opening myself up to ridicule, but here goes. And no....I'm not on drugs.



Local Ford dealers use a "high pressure" flush which I think is a bad idea and I simply don't trust the quicky lube joints. I want a safe and economical way to change the fluid more often. After researching how the "low pressure" units work I think I have an idea that may work.







Theory of operation:

1) Connect this contraption up to pressurized trani line.

2) Pump just enough air into airvalve so that clean fluid from container "B" rises to top of return line. The check valve will prevent air from going back into the trani. This in effect will "prime" the system.

3) Connect return line to top of radiator.

4) Start engine, new fluid should immediately start being pumped into the radiator at the same amount that is coming out. As fluid enters the drain container A it will displace air into container B at the same rate/volume, thus creating the pumping action.

5) Shut off and disconnect when fluid draining into container A is clean and certainly before the new fluid runs out in container B.



Notes:

1) Entire system is airtight and only air passes between the two containers.

2) Might be able to get away without priming the "machine", it will just take a few moments to build up enough pressure in the containers to start the new fluid flow.

3) Should be able to make this for about $30.

4) This assumes trani line to top of radiator is pressurized, if not just reverse.



So what do you guys think? I'm really not on drugs.



Tim[Broken External Image]:

 

[Tim Reynolds]

Oops, I'll shrink that pic down a bit.

 

[Dreman]

It's a shame that you're not on drugs. It would explain so much. (Just kidding! Please don't use drugs!)



The only problem I see is the compressibility of air. You won't move much fluid out until the air pressure builds up. Otherwise it looks like what the shops use.



It would be easier to tap into the line to the front cooler. Isn't that connection a hose clamp?

 

[Tim Reynolds]

The "priming" should prepressurize the air to the point where the fluid is just ready to flow on the return. From there you will always have the same volume (and hence pressure) between the two containers.



Make sense?



I'm still trying to figure out how to resize this pic.

 

[N J]

I was just wondering about why you think the dealer's "high pressure" system of chaging the fluid is bad?



Also, how often do you think the fluid should be changed, I think my owner's manual doesn't call for it until like 100,000 k.m. (in Canada) ?????



Thanks.

 

[Dreman]

The reason I ask is I don't know if there is any back pressure on the return line. A one-way check valve keeps the fluid from backing up, but it doesn't open up until the pressure on the "from" side is greater than the pressure on the "to" side. If the pressure has to build up, any air in the system will have to compress until it is at the necessary pressure. And there won't be any fluid flow into the transmission until that time.

 

[Kevin Palmer]

Tim,

here is a FREE program that will re-size your pictures for you. Super simple to use.



Once you down load it all you have to do is "Right Click" on the file name of the picture you want to re-size, (not the picture itself, just the file name like any other file in a list. The picture does not need to be opened). In the "Right Click" list you will see a new option that says "Resize Picture". Select this option, it will give you some choices to choose from. It will re-save the picture under the same name and add a size description. You will not lose or alter the original picture.

 

[Tim Reynolds]

Nick: I think most on this forum agree that 25K to 30K "miles" is the best change interval. Seeing as many have had transmission problems, I would change sooner than 100k km's. There is almost endless discuss on the internet regarding flush vs drain and filter but I don't think that anyone can argue the merrits of new fluid replaced in a safe (non pressurized) manner.



Dreman: Not sure I'm following you (sorry) but I'll take a stab at it. The check valve operates at one psi so it should allow flow from the trani very easily. Now if there is substantial back pressure on the return that is another issue. Maybe do a partial prime, connect the return and finish priming???



Coastiejoe: Thanks, I ended up resizing it in MS Word....but appreciate it.

 

[Dreman]

Actually I was thinking there was a check valve on the return line as well, and looking again I see you don't have one there. I understand your confusion.



Really it should work. There probably isn't any back pressure on the return line, and if there is it will just take a moment or two to pressurize. Give it a try and let us know how it works.

 

[Todd Z]

The only issue is you would have to make sure it was a sealed pressurized system... I believe you did....

OR you could add the fluid through the dipstick at the same rate it was pumping out the tranny line and save a ton of work..

The fluid entering the cooler is from the converter, it returns back to the pan, IT doesnt return into the tranny valve body or the converter...

Good luck either way!

Todd Z

 

[Tim Reynolds]

Does anyone know what the fluid flow is to and from the radiator and cooler?



Side note: If I had to do it all over again (owning it since new) I would have dropped the pan at 15 to 20K to clean pan, check for problems and new filter. My guess is that the majority of crap you'll get at the bottom of the pan is due to break in. I would then install an external trani filter and just do flushes every 25k for the life of the truck, changing the filter everytime.



Anyone use an external filter like the perma-cool unit?



I just had my trani serviced (drop pan, filter and drain) and there is a small leak around the pan now. Oh well, I'm still glad I had it done as the filter looked like garbage.

 

[Tim Reynolds]

[Broken External Image]:



This is what I am basing my theory on. This image is from the Perma-Cool website. Notice the arrows for fluid flow.



Todd, I though about simply filling back in the dipstick while pumping out but won't that leave all the old fluid in the radiator and cooler?



Thanks guys.

 

[Dreman]

If Todd is right and the return line goes straight back to the pan, then it should work.



I'm sure the fluid flow is RPM dependent. I have no idea what it would be. Probably no more than 1 gal/min at idle.

 

[Tim Reynolds]

I've read on another forum that a well respected member recommended the following procedure for a flush.

1 disconnect top radiator lines and connect "radiator" to a drain hose in a bucket

2 run engine until you see bubbles in drain line or hear gurgling

3 fill equal amount of new fluid in dipstick

4 repeat until flush is complete



I have two burning questions. One: is the flow in the above diagram correct? He mentions flow coming out of the top of the radiator. Two: if you do a flush this way, how do you get all the fluid out of the radiator and cooler? If it flows up through the radiator this question is mute obviously.



Maybe I don't have to build this "machine" afterall, I like the idea of keeping it simple. Still thinking about that external filter, now would be the time to do it while my internal one was minty fresh.



Any thoughts?

 

[Richard L]

Time R,

Your flow diagram is correct.

I do not agree that you should just dump the fresh fluid back down the dipstick tube. The hydrolic system in automatic transmission is very complicated and varies greatly between manufacturers and even different transmission models from the same manufacturer. With the latest addition of electronic controls and sensors, the transmission's plumbing has become hopelessly complicated without diagrams, schematics and tutorials.



The fluid returning from the cooler may or may not just dump into the pan. There is a good possibility that it may be directed to some other internal component. If you just direct the fluid back through the dipstick tube, you may be depriving a critical component the cool fluid it needs. Most automatic transmissions only send a portion of the fluid to the cooler while the rest goes to various parts of the transmission.



The fluid servers 3 purposes... Shift control, lubrication, and cooling. All parts of the transmission require pressurized fluid to operate, especially the clutches, bands and valve body. The other parts of the transmission are bathed in the fluid to provide lubrication and cooling.



While I applaude your ingenuity, I'm not sure that the end results would be worth your efforts.

If you consider that you would change/flush your fluid more frequiently, you are not considering the cost of the fluid and the labor involved.



I would consider an external fluid tank that holds and additional 5 quarts of fluid that is connected in series between the the transmission and the cooler. Every 6K-8k miles, simply drain the external tank and refill with 5 fresh quarts of Mercon-V. Now you are effectlvely changing all your fluid every 12K-15K miles. The most difficult part would be finding space for the external tank, so it would likely have to be custom made to fit an odd space.



...Rich

 

[Kirk Nolte]

Sam. I think your onto something here.

I have small modification that will take care of any pressure issues or air bubbles.

Remove the return line from the rad cooler and connect it to a container with a small spigot at the bottom and filled with trany fluid and hold this container above the cooler hieght. Letting gravity produce a constant flow. Allow fluid to circulate tback hrough the cooler and then be collected in a seperate container.

Do this until you see clean fluid run out of the cooler hose.

Just an idea what do think?

 

[Dreman]

Why add an extra tank? Simply remove the transmission pan, install a drain plug, and drain 5 quarts out every time you change the engine oil. You will never get all of the fluid, but you will get 99% over time. i.e the first time gets 50%, the second gets 50% old fluid and 50% new fluid, so you now have 75% new fluid, then 87.5% new, then 93.75%, etc.

 

[Richard L]

deman,



The extra tank holds an additional 5 quarts of fluid which increases the normal 10 quart capacity by 50%. That will provide a significant decrease in the temperature of the fluid circulating through the transmission. And heat is the biggest enemy of the transmission and the fluid. The additional volume of cooler fluid will allow the fluid to last longer between changes. If the extra tank can be fitted in a convenient location with a drain cock and hose, it could be easier to drain and refill without the need to jack up the vehicle or crawl underneath.



This is the same concept used by large diesel trucks and race cars. Race cars like NASCAR stock cars us a dry-sump with a scavaging pump to pump the oil from the oil pan into a large holding tank that holds much more oil than would fit in the engines oil pan. This arrangement also prevents oil starvation in high G-force turns that could push the oil in the oil pan up the side and leave the oil pick-up sucking air!



Even a transmission flush will not remove 100% of the old fluid. Most companies will claim their flush will replace 97%-98% of the old fluid. That may even be a bit of an exageration, however dropping the pan to change the fluid will only change about 50% of the fluid.



...Rich

 

[Tom Schindler]

Dreman,



That is kinda what I do. Tranny shifts perfect. I drain, fill. Drive for a while. Drain, fill. Drive for a while. Drain, fill. Good to go.



I might not get the estimated 99% of the fluid out, but the fluid I have in the tranny is red as can be.





Tom

 

[Dreman]

Rich



I understand that you won't get all of the fluid each time, but I'm saying that if you change some of the fluid several times, you will get about the same amount of fluid changed by the time a normal change interval comes around. Say instead of changing the fluid every 30k miles, change 1/2 the fluid every 5k miles. So instead of paying $100 every 30k miles, spend $18 every 6k miles, which adds up to about the same thing.



And if you want more capacity, get a deeper pan and an extended pickup tube. That will give you more capacity, and fewer problems with high g-forces uncovering the pickup tube. And you'll change more of the total fluid volume with each drain and fill. And you already know where to put it!