Tranny flush vs. Change... Which is better????

[Alan Peters]

I'll have 42K on it and had a Flush done at 22K. Its an 03 ST. Many people are telling me not to flush because it put great strain on the internal parts of the trans. Rather drop the pan and change the filter and put new mercon V in. Which one is better?



Big Al

 

[Bill Ellis]

You will hear convincing arguments on both sides of this debate. However, the notion that a full flush stresses the trans is nonsense. During a flush, the transmission's internal pump transfers the fluid so it really doesn't know that anything different is happening. It just pumps away like usual. A full flush is the only way to change all the fluid. A pan-drop only changes about 25% or so. It is true, however, that a full flush of a high mileage tranny that has never had any service can cause problems because the detergency of the new fluid can dislodge a lot of normally harmless gunk that has built up over the years which when circulated through the system starts to clog things and then tranny dies.

 

[Todd Z]

First question is how is the fluid ????



I think I would do a pan and filter now, and then re flush at 60K..



The flush only strains the tranny if done wrong... Most flushes are done with the truck idling and using its own pump..



Todd Z

 

[shawn stonbraker 2]

Like "Z-Man" said. Just do a drop pan (and while you're at it, throw a drain plug onto the pan (see project section)) and fluid change. The drain plug will come in handy if you ever have to change the filter again. Flush later.

 

[Alan Peters]

The dealer sent coupons for 99 for a flush and 69 for only a change. I'll probably just go with a change.



Big Al

 

[shawn stonbraker 2]

Big Al, if you have the time and can do it yourself, there is a project for changing the filter and putting a drainplug on the pan in the projects section. Total cost to do myself was about $39 and that was with the drainplug. I also did the EPC adjustment (which the dealer won't do) while I was in there. Made the shifts more firm. But $69 isn't a bad price if you don't have the time or place to do it. Just be aware of "additional" charges some of these dealers try to put onto these coupon deals.

 

[Alan Peters]

I've always been fearful of trying something like changing tranny fluid. Oil changes, battery swap out, bulbs, switches, bolt on type stuff is pretty straigth forward. I should give it a try. I would like to put motorcraft fluid back in. Can I find Mercon V at shops like autozone or an autoparts store? Or should I just head to the dealer?



Big Al

 

[shawn stonbraker 2]

If you get it at a dealer, make sure what they give you is in a black bottles. The stuff in the red isn't made for the ST. I got mine from Advance Auto Valvoline Type V. Just check out the project section and it really isn't hard to do at all. Just alittle messy since it doesn't have the drainplug to begin with. I've drained my fluid to put in fresh twice since and the plug is a wonderful thing. I'm planning on getting mine flushed here shortly.

 

[Richard L]

Big Al,

I don't know who is telling that a tranny flush is stressfull to the transmission, but my guess it's a shop or garage that doesn't have the flush machine.



As previously stated, there is not stress on the transmission because there is nothing different except that the transmission pump is pumping out old fluid while it's being replaced by fresh fluid. There are some flush machines that use additional pumps to move the fluid faster, so don't use them. Only use the flush machines that only exchange fluid using the transmissions internal pump. It will take about 15-20 minutes to pump 14 quarts of fluid in and out of your transmission, but that's not too long.



The advantages to the flush are that it replaces about 98% of the old fluid with new fluid while a conventional drop-the-pan only changes about 50%-55%. The remaining fluid is trapped in the transmission and torque converter.



Another advantage of the flush is that you will not induce an transmission pan leak because someone used the wrong gasket or sealant, or did not get all the old gasket off, or overtightened the pan bolts, etc



Disadvantanges are that you don't change the transmission filter, but that is more of a myth than reallity. The transmission filter does not work like an engine oil filter that needs to remove combustion byproducts that are corrosive. The tranny filter is really nothing more than a screen to prevent large chunks of debris from getting recycled though the transmission in the fluid. It is primarly a surface filter and particles that it stops at the surface will fall back into the pan when the engine is shut off. Anything that gets by the filter/screen is too small to cause any harm to the transmission.



If you flush you fluid regularly every 25K-30K miles, you tranmission filter will easily last 100K miles or more. Then you can have the pan droped and the filter changed.



Heck, even GM has been making transmission that are sealed and do not need any service or filter changes for 100K miles. The only difference is they use Synthetic fluids.



I have had transmission flushed done on both of my Sport Trac's and never had any transmission problems. In fact the flush on my 2001 made it feel like it got a tune up. I got noticable better accelleration and firm quick shifts as soon as I drove it home from the shop after the tranny flush.



...Rich