Gadget does a good job of describing the two transmission flushing options -- for the pump inlet flush you'll have to go to a shop that has the machine: http://www.gadgetonline.com/TransFlush.htm

And if wanting to do the cooler line flushing option on your own in your driveway, this is a great how to (might need to look up your specific vehicles torque sequence, etc, however, as this is for a 2002 4Runner): http://home.centurytel.net/stevenjac...sh/tranny.html

 

sorry to bump an old post, but I have the same transmission in my V6 3.0 94 pickup and I recently drained the transmission and transfer case. my question is..

before the drain, it had the proper amt of fluid, now it reads high, and i got more fluid out than I put in through the fill tube. Im worried that its reading high when its actually low. I put in about 4 qts and its reading well above the hot/high even when cold. Should I check the transfer case fill port and see if I can feel fluid with my finger? I havent driven it even a mile, but Im about to go from texas to wisconsin with it.

thanks
smalls

 

In order to get the proper reading on the A/T dipstick, the engine has to be running and at normal operating temp. if engine is off it will read over the max. line.

 

so there does not seem to be a definite answer to the question whether or not the A340H fills the transfer case on through the transmission pan...well I had an interesting experience today. I went to change the solenoids, so I decided to drain all of the fluid. I drained both pans and then I went to drain the transfer case, I opened the fill plug, 24mm first as good measure to make sure I could refill, GUSH!!! I had tons of ATF pouring out, easily 2 qt. I then opened the bottom plug allen head and drained the rest. It is impossible to fill the transfer case that full, therefore I believe that it is good practice to fill the TC just like the manual says with roughly a qt. and then the transmission system fills it the rest of the way.

 

I think you are correct.. after driving about 100 miles my levels all were fine.

smalls

 

With autos, the transfer case is actually in two parts, the transfer case chain/gear drive is the rear most portion. It will not fill from the tranny, unless there's a seal broken between it and the front case. Why you run tranny fluid in both with an auto for instance instead of gear oil...

To reiterate -- rear should only fill through fill hole, front will refill from tranny.

 

Well I filled the rear of the case, the chain area, with about a qt that filled it to the fill port. I checked it after I ran it and it is above the fill port now and ATF pours out just like when I drained it, so it is filling from somewhere else as well but it works just fine in 4x4.

 

It depends on which auto you have.

I believe the A340H has a fluid connection inside, so fluid in the transfercase can go into the transmission and vice versa. Put another way, the A340H is always "both" the transfer case and transmission; you can't, for instance, put on a different transfer case. http://personal.utulsa.edu/~nathan-b...27descript.pdf

There are two drain plugs because, so far as I can tell, the bottoms of the cases are below the "sill" between the two units. So you can add fluid at one place, but you need to get the last of it out through two drains.

For what it's worth, the transfer case is a small "automatic transmission," with planetary gears and hydraulic shifters.

 

Well it isn't supposed to do that. As stated, the A340H has a gasket between the upper transfer chase and the chain drive. Apparently your gasket has failed -- as a precaution against that failure is why this transfer chain drive uses tranny fluid despite gear oil probably being a more effective lubricator in this situation...

I'm unsure of all the repercussions, but I'm sure the standard overly high engine/tranny oil problems will likely exist there as well... Not to mention you're loosing tranny fluid into a separate environment.

You definitely want to fix that, but I believe it's a pain... I think it was Gevo who had that problem 6 months or so back and took it to a tranny shop and just had them do it as at least the chain case needed removed, possibly the hole tranny system...

 

Well I respect your opinion on this but I am not convinced that is the case. There are 2 others on page one of this thread that claim that you put a qt in to keep it from running dry on start up, thus the fill plug, but that the valve body will fill the chain case on its own. Again, I have 150,000 mi and besides the solenoid that was sticking I haven't had any issues with the transmission or 4x4. It's not leaking anywhere and there is a jiggler vent similar to the rear and front diffs on top of the tcase. I would be losing oil out of that if it was over filling the tcase. I bet it would cost at least a days labor at 100 or more an hour to do that work besides parts. I would rather get another trans with a gear driven tcase than drop money into this one especially since nothing is malfunctioning at all. I'm not saying you're wrong I'm just not convinced you are right.

 

With 100% certainty they are wrong if talking about the chain case.

As previously stated, the transfer case on this transmission is 2 parts. The tranny drain plug behind the tranny is for the hydraulic control unit portion of the transfer case. To fill this after draining is why the factory repair manual says to shift through from H2 to H4 to L4 and back again or something to that effect. The rear and lowest portion of this is the chain drive. The primary purpose of the fluid here is to keep the chain drive lubricated and cool -- why the oil cooler runs off of this. It is not under high pressure and should not be filling. The only reason for it doing so is a failed seal/gasket between the hydraulic control portion of the transfer control unit and the chain case -- remembering that the hydraulic portion shares fluid with the tranny.

Your call on choosing to fix or ignore the issue, but don't plead ignorance or confusion.

 

This is an old thread, but a correction needs to be made. The cavity for the chain is separated from fluid from the main tranny pump with a seal ( just rebuilt three of them by the OEM Toyota manual).
You have to fill the cavity in the dack through the plug or you will have a dry chain and damage the unit. This cavity has 1.2 quarts in it. The person that took two quarts out of the cavity and only filled from the tube needs to replace the seal under the chain drive gear.
One of the units I just rebuilt came to me with no fluid in the chain cavity and it had been running for 50000 miles with the transmission full. It had good seals but know one ever filled the cavity.
Beware the fill instructions in the manual are in two different locations, one for the tranny and one for the transfer case.
Hope this clears the issue up.