AP9
Well-Known Member
- Joined
- July 23, 2012
- Messages
- 251
- Reaction score
- 5
- City, State
- Chicago SW suburbs
- Year, Model & Trim Level
- 2000 XLT 4WD, 4.0L OHV V6
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?
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?