5R55E Transmission Fluid Change

Though I've read varying versions of the story, in general it seems as though a pressurized or reverse-flow transmission flush is a bad idea in these transmissions, as it can cause sludge or other contaminants to clog or damage valve bodies and solenoids.

There are even those who will go a step further and say that just replacing fluid will cause trouble, since the existing transmission fluid may already be supersaturated (fully saturated during "hot" operating conditions) with contaminants that have settled, and the fresh detergents in the new ATF will stir up these settled deposits which could then cause problems before they even get to the filter.

So I was thinking: if existing garbage in the system is really that big of an issue, why would "flushing" the system with an excess of fresh ATF be problematic? Sure it may not prevent ALL problems, but it would reduce the likelihood.

Here's my logic:

Pull the pan, clean it out, and change the filter. Then attempt a slightly modified version of the following procedure:
http://www.explorerforum.com/Singleton/web/pages/at1.html
not pinching the hose or restricting flow (which I'd think would cause undesirable backpressure or unintended upstream turbulence in the transmission), but rather using a large new bucket of ATF, and a large waste bucket of "old" ATF. And by "large new bucket of ATF" I'm talking about one of the 5-gallon pails you can buy Dex/Merc in. Maybe even add some transmission additive/cleaner to it. Then, when that 5-gallon pail is getting close to empty, throw in 12 or so quarts of good Mercon V, and stop once that's in the transmission. Then flush out the TOC and lines so cooler contaminants are removed at the same time. Top off with Mercon V as needed.

That way, a full five gallons of "fresh" ATF flows through the transmission to pretty much guarantee that all old fluid gets out, and hopefully carry with it any other garbage that's not accessible by just dropping the pan and changing the filter--even if it gets stuck further downstream in something, that's 5 gallons of flow so hopefully it'll get knocked out eventually. At the same time, nothing in the transmission is subjected to abnormally high fluid pressures or incorrect direction of flow. Sure it would be a bit expensive and kind of a waste of ATF, but a lot cheaper than a transmission rebuild--and the ATF can be recycled anyway. Who knows, maybe some of the "later" batch of the ATF to come out could be recaptured and used in the power steering or something if it's clean enough.



Want to know what other peoples' thoughts are on this. Pointless? Good idea? Terrible idea? Waste of money?

It's a 13 year old transmission and while I don't agree or disagree with the change the fluid and it quits myth, I do think you should be careful.

FYI - Here's my yearly fluid change process. Disconnect the upper tranny cooler line from the top of the radiator. Plug the radiator end, put a hose on the line coming from the tranny and route it into a gallon container.

Start the engine and let the gallon container fill up, then shut it down. Add 4 quarts and reconnect the cooling line.

Been doing that every year since I've owned the truck. Takes 10 min, no mess and the fluid properties aren't drastically altered with this method.

If your fluid is dirty, I'd put a schedule of monthly in place until it clears up.

Good luck!

5r55e flush complications

According to available documentation the external cooling loop on the 5R55E does not open until the temperature in the torque converter reaches 150 degrees F. However, thru simple experimentation I learned that even at cold engine start if the external cooling loop is broken, there will be ATF output flow from both the inlet and the outlet lines. The flow from the outlet line exceeds the flow from the inlet line.

The external cooling loop only circulates a portion of the ATF in the transmission. It will take considerable flow to replace most of the fluid in the transmission. The system works comparable to a low flow bypass engine oil filter.

my98nnj said:

It's a 13 year old transmission and while I don't agree or disagree with the change the fluid and it quits myth, I do think you should be careful.

FYI - Here's my yearly fluid change process. Disconnect the upper tranny cooler line from the top of the radiator. Plug the radiator end, put a hose on the line coming from the tranny and route it into a gallon container.

Start the engine and let the gallon container fill up, then shut it down. Add 4 quarts and reconnect the cooling line.

Been doing that every year since I've owned the truck. Takes 10 min, no mess and the fluid properties aren't drastically altered with this method.

If your fluid is dirty, I'd put a schedule of monthly in place until it clears up.

Good luck!

Click to expand...

Basically only taking some of the old fluid out and "diluting" it with new fluid, though allowing the TOC & lines to drain as well? I'm assuming that too much of a sudden change in transmission fluid properties could cause problems or require the transmission to retrain shift points and behavior?

2000StreetRod said:

According to available documentation the external cooling loop on the 5R55E does not open until the temperature in the torque converter reaches 150 degrees F. However, thru simple experimentation I learned that even at cold engine start if the external cooling loop is broken, there will be ATF output flow from both the inlet and the outlet lines. The flow from the outlet line exceeds the flow from the inlet line.

The external cooling loop only circulates a portion of the ATF in the transmission. It will take considerable flow to replace most of the fluid in the transmission. The system works comparable to a low flow bypass engine oil filter.

Click to expand...

So this means that only once at operating temperature, the pump starts going or increases its flow? Perhaps just a simple thermostat? In that case, even five gallons of "pusher" ATF may not be enough to get all the old fluid out. Hmm....

I say that's good advice.And one thing that I've been doing with good results (on trans. that don't have one),is to install a 3" by 1/4 to 1/2" donut magnet in the bottom of the pan.Locate it away from any solenoids.Mix a little batch of JB Weld and install.It is a passive way of getting rid of ferrous metal particles from continuously circulating with the fluid.It will catch any size iron based particle,something the filter can't do.Don't put it near the inlet of the filter as the flow is too fast.It's a "passive" way of catching THE most damaging metal (steel or Iron),you can have in the fluid.I learned this trick back in the 80's when I worked at a GMC Truck dealership.It was an addon kit from the factory for heavy duty automatic tansmissions.Proven to lengthen the life of the trans.Because they were failing inside the warranty period.This trick,got more miles & time to get them out of warranty.That is what they told me.Was it crooked? Depends on how you look at it I guess!Next time you drop the pan,you'll see what's what,believe me.

2000StreetRod said:

5r55e flush complications

According to available documentation the external cooling loop on the 5R55E does not open until the temperature in the torque converter reaches 150 degrees F. However, thru simple experimentation I learned that even at cold engine start if the external cooling loop is broken, there will be ATF output flow from both the inlet and the outlet lines. The flow from the outlet line exceeds the flow from the inlet line.

The external cooling loop only circulates a portion of the ATF in the transmission. It will take considerable flow to replace most of the fluid in the transmission. The system works comparable to a low flow bypass engine oil filter.

Click to expand...

Yes, You are right. I tried to flush tranny from cooler lines today (at cold start) and BOTH lines have output flow from those lines. At this moment, only 6 quaters were push out of tranny, using pan and filter replacement method. How i can take out rest of fluid (6 or more quaters)?. Thanks

adolfomantis said:

Yes, You are right. I tried to flush tranny from cooler lines today (at cold start) and BOTH lines have output flow from those lines. At this moment, only 6 quaters were push out of tranny, using pan and filter replacement method. How i can take out rest of fluid (6 or more quaters)?. Thanks

Click to expand...

I forgot to mention, I replaced 6 quarters from pan with fresh fluid and new filter, of course. I tried to disconect cooling lines how I said before, but both lines have output flow when i made a 5 seconds cold start test. How i can take out rest of old fluid?. I dont want to start engine again until take out that old fluid. Thanks in advance

I don't know about the export models but the U.S. 2004 XLT has a 5R55S or 5R55W instead of the 5R55E. Which transmission do you have?

Some of the 5R55S transmissions have a large plug on the bottom of the torque converter housing. When the large plug is removed there is access to the torque converter drain plug.

2000StreetRod said:

I don't know about the export models but the U.S. 2004 XLT has a 5R55S or 5R55W instead of the 5R55E. Which transmission do you have?

Some of the 5R55S transmissions have a large plug on the bottom of the torque converter housing. When the large plug is removed there is access to the torque converter drain plug.

Click to expand...

Hi. Ok, In Venezuela, Explorers are (allmost) same than U.S. models: (Are assembled in Ford´s Plants at Venezuela with U.S. made parts). So, my 2004 Explorer has a 5R55S tranny. Let me see if my tranny has a plug at TC housing. I will check tomorrow and comment later. Thanks a lot.

Ok... and some days after... My transmission does not have a plug on torque converter housing. Finally, I drained fluid at pan only and replaced filter. Transmission failure (Did not change from 1st to 2nd at "Drive") was solved with fluid change. I noticed some debris al two soneloid and also I cleaned it. Thanks guy. I will wait for 10K milles more and repeat change.

Hey guys, sorry to resurrect a dead thread, but here’s a tip from over in BMW land, where we use GM and ZF automatics that you can’t drain the TC on.

Instead of doing the pump and flush method, which some have mentioned the issues with here, drop the pan and get out as much as possible. Replace the filter, toss in the correct amount of fluid (and seeing as how there’s no dipstick, have fun, especially when “full” is “dripping fluid out fill hole when GKE module says exactly 40C while running”). 500-1000 mi later, do the same thing. Seems the power flushes or even the half-fluid change can end up loosening so much crud you plug the filter, then the trans gets insufficient flow and burns itself out. Worked like a charm for me, other than getting the damn thing filled right.

Might as well ask a question while I’m playing thread necromancer... my trans is overfull. Bout an inch too high when read warm in neutral. With the Bavarian moneypits, thats as deadly as underfilled. What about here?

Biggest thing to worry about is blowing a rear seal. I don't think that would be high enough to screw with the input shaft.