ATF+4 or Dex/Merc

[PjWulfman]

2003 TJ X
4.0 inline 6
225,00 miles
3" lift 33" tires
42RLE transmission, I think? 1 thru 3 with optional Od.
When I first purchased her last summer I knew nothing about these vehicles ,and only a bare minimum about vehicles in general. Shortly after purchasing I was invited down to the Beartooth Highway to do some jeepin' and on my way back to Great Falls MT she started shifting weird. Pulled over to check things out and discovered my tyranny fluid was low. Middle of nowhere, no reception to look up info, no owners manual, and a podunk service station with 2 kinds of ATF. I picked one, and didn't realize later it was probably the wrong choice.
PO tells me he used Dex/Merc transmission fluid. Driven jeeps almost his whole life. Everything I've read points to ATF4. I'm replacing the filter and gasket so I'm thinking now is the time to decide. Would like to do a flush but not sure how and I'm running out of time in the shop I've commandeered.

 

[cliffish]

ATF +4 is what you want, will need 9-10 qts for a full flush, just did this on my 05 over the weekend. disconnected at the d/s bottom of the radiator the incoming transmission line (it is actually the output line of the transmission cooler). You want to flush everything if you mixed fluids.

 

[Jerry Bransford]

Your automatic transmission absolutely MUST run on nothing but ATF+4. Don't even consider Dex/Merc ATF for your transmission. If the bottle doesn't say ATF+4 in big letters on the front label it's the wrong stuff.

The transfer case doesn't care what type of ATF it runs on but you might as well stick with ATF+4 for it too.

 

[PjWulfman]

"The transfer case doesn't care what type of ATF it runs on but you might as well stick with ATF+4 for it too."

Jerry, can you explain that in further detail?

 

[cliffish]

Transfer case has it's own supply of atf, that should be drained as well, it is just easier to use the same fluid atf+4 although it does not require it. uses about 1.2-1.5 quarts, has it's own drain plug and fill plug is just above.

 

[Drizit]

He may have run the other stuff for years in all his jeeps the the 42rle is a newer transmission designed exclusively around the newer ATF+4. Just because it worked in an older trans doesn't make it a good idea. Do that full flush you talked about and put in atf+4. The tcase just wants something slippery in it, but it's nice to only need one kind of fluid for everything. Hell it's probably why the 03+ was converted to atf+4 for the power steering to.

—
There must have been a time
when we could have said no.

 

[PjWulfman]

I'll have to do some research. I guess I wasn't aware that a transfer case existed and needed to be added to my maintenence schedule.

 

[MrMark52]

Hey @cliffish - hope your still around - sorry to resurrect an old thread -

I want to do a full fluid flush on my tranny - you say the driver side port on the radiator is the output of the cooler. My question is (for clarification) - is fluid going to blast out of the radiator or out of the tubing disconnected from the radiator that leads back to the tranny?

So procedurally, if it comes out of the radiator, then I need to plug the tube and find a hose barb that will screw into the radiator, then attach a hose that leads to a drain bucket.

Or, if it comes out the tube, then I need to plug the radiator and slide a hose over the end of the tube.

Or, and @Jerry Bransford might could better answer this - in lieu of (after dropping the pan, changing the filter, reinstalling the pan and replacing the fluid lost when dropping the pan, then disconnecting the line from the radiator) then starting the engine to pump a few pints out, then kill the engine, add what was removed, then repeat - why couldn’t one just connect a bottle of new fluid to whichever point that the fluid goes in at (radiator or cooler line) start the engine, and while fluid was being pumped out into a drain pan, ew fluid was being drawn into the system? New bottle of fluid could either be drawn from the bottle By the pump, or flipped over to allow a gravity feed (assuming air is allowed into the bottle).

 

[cliffish]

Hey @cliffish - hope your still around - sorry to resurrect an old thread -

I want to do a full fluid flush on my tranny - you say the driver side port on the radiator is the output of the cooler. My question is (for clarification) - is fluid going to blast out of the radiator or out of the tubing disconnected from the radiator that leads back to the tranny?

So procedurally, if it comes out of the radiator, then I need to plug the tube and find a hose barb that will screw into the radiator, then attach a hose that leads to a drain bucket.

Or, if it comes out the tube, then I need to plug the radiator and slide a hose over the end of the tube.

Or, and @Jerry Bransford might could better answer this - in lieu of (after dropping the pan, changing the filter, reinstalling the pan and replacing the fluid lost when dropping the pan, then disconnecting the line from the radiator) then starting the engine to pump a few pints out, then kill the engine, add what was removed, then repeat - why couldn’t one just connect a bottle of new fluid to whichever point that the fluid goes in at (radiator or cooler line) start the engine, and while fluid was being pumped out into a drain pan, ew fluid was being drawn into the system? New bottle of fluid could either be drawn from the bottle By the pump, or flipped over to allow a gravity feed (assuming air is allowed into the bottle).

Yeah, I am still here, Jerry would better be able to answer this. I know it does not blast out, I believe it comes out of the tube coming out of the transmission. I t also might depend on the year also, Mine is an 05.

 

[MrMark52]

Hey @Jerry Bransford - your thoughts?

a) for where does the fluid come out and go in when disconnecting the driver side tube at the radiator, and

b) would you agree to my methodology of providing a supply of fluid to which ever of the connections is the suction while allowing the discharge of fluid to be directed to a catch pan of sorts? Just seems like this would be easier than all the starts and stops to check the fluid levels.

 

[Jerry Bransford]

Hey @Jerry Bransford - your thoughts?

a) for where does the fluid come out and go in when disconnecting the driver side tube at the radiator, and

b) would you agree to my methodology of providing a supply of fluid to which ever of the connections is the suction while allowing the discharge of fluid to be directed to a catch pan of sorts? Just seems like this would be easier than all the starts and stops to check the fluid levels.

The output side of the transmission cooler on your 2003 TJ is on the driver's side. Connect a rubber tube to the driver's side output port at the bottom of the radiator and run the other end of that hose into a 5 gallon bucket or similar. The transmission will pump the old ATF+4 out from that driver's side port.

You add the fresh ATF+4 via a funnel inserted into the transmission dipstick tube. You can continually add fresh ATF from there until the output going into the bucket turns bright clear red.

 

[MrMark52]

The output side of the transmission cooler on your 2003 TJ is on the driver's side. Connect a rubber tube to the driver's side output port at the bottom of the radiator and run the other end of that hose into a 5 gallon bucket or similar. The transmission will pump the old ATF+4 out from that driver's side port.

You add the fresh ATF+4 via a funnel inserted into the transmission dipstick tube. You can continually add fresh ATF from there until the output going into the bucket turns bright clear red.

Aghhh - Thanks Jerry! I just couldn’t get that logic through my head after all the reading I had done.

So you add fluid at the funnel at the same rate you see the bucket filling.

But without capping the the now open cooler line going back to the transmission, wouldn’t air be sucked into the system?
Seems like that after filling the tranny with fluid after a filter change - that putting a rubber hose on that tube and feeding up thru the engine bay (avoiding the fan and moving parts), put a funnel on it, start engine and pour fluid in funnel at rate fluid was being pumped out would minimize the pump running dry.

 

[Jerry Bransford]

Simply add fresh ATF+4 at or close to the same rate it's dumping out into the bucket and you'll be fine. Just don't go eat a hot dog while it's pumping ATF out. It doesn't pump it out THAT fast, you can easily keep up with it. No worries about air either.

 

[MrMark52]

But -

what if I use the engine manifold to heat up my hot dogs - your saying I can’t eat it once heated while adding fluid?