pplusent

1993 4runner with 3.0 V6 and a340H transmission 4x4 cooled through radiator cooler then routed through a separate cooler rated for vehicles over 30000 pounds.
The question is what should my RPM be at 65 MPH if I am getting full lock up?
The tranny is over heating at speeds above 65 MPH, but runs perfect other than the heating issue.

rworegon

What's telling you the tranny is overheating? Fluid is good and at correct level in the tranny?

Many of us have taken the radiator cooler (built into the bottom of the radiator, yes?) out of the circuit and just go from tranny to external cooler and back. Why? Two reasons: 1) eliminates the pink milkshake potential and, 2) the radiator coolant temp is likely pre-heating your tranny coolant before it goes to the external cooler.

pplusent

Fluid is all new and the level I have to keep at the lower hot mark on the dipstick, or when the OT light comes on it will also burst a shot of fluid out the vent and on to the exhaust for some nice white smoke.
I am considering taking the rad cooler out of the loop, but what I am questioning is if the converter is locking up. There was a manufacture here that made some bad ones that don't lock up and the one in this 4runner was bought around that time and is painted the color the manufacture used. Also when I test the stall speed on the torque con it's coming into stall at 1100 rpm, when it should be at 2200.Also all frictions, steels, bearings, seals and O-rings are new. Only 100 miles on tranny. Shift kit also installed. Solenoids are original, but tested good.

Marc

No one can tell you what the rev's should be without knowing tire size and gearing.
It's only about a 500 rpm drop when the converter locks up.

I can tell when mine locks up. It drops when I reach a steady cruising speed.
Sometimes against the wind it won't lock up unless I click O/D off.

dropzone

iTrader: (6)

Marc is dead on...need gear and tire size.

pplusent

It has 235x15's on it for tires. the gearing is stock, but I do not know what it is. the truck is all stock, only improvement is urathaine suspension parts in the front end all other parts are stock replacement parts.
I do see it going into 4th/OD and the speedo shows 4MPH faster than it is actually going. right now it is running at 3000 @ 65mph and 3500 at 75mph, but anything over 65 over heats it in about 10 miles then I shut it down for 5 min and it is good for another 10, if I stay at 65 it will go 40 mile then over heat. I am thinking maybe the lock up solenoid is leaking and not getting total lock up, or maybe the converter is bad, it is new, but sat around for two years? I have no idea at this point. I just know I would like to do some 4 wheeling just cant get it there without stopping every ten miles. I already have over 2500 in parts alone at my jober cost into this project and would like something more than a daily driver on surface streets. God only knows how hot the tranny is going to get in the summer when it's 118 degrees out side with the ac running. the good thing is I have my ac putting out 38 degree air. if only I could get that to the tranny cooler!

scope103

I think you are on the right track. The only time I can get my transmission overheat light to come on is when I am pulling up a long hill (Sierra Nevada) on cruise control at freeway speed, where the grade is just right to keep the transmission from locking up. If I drive "by hand" I'll come off the gas just enough to keep it in lock-up, and then I don't have a problem. (Incidentally, this has happened with air temp well below freezing, so don't try to tell me that taking the trans cooler out of the circuit is a good idea!)

Like the others, I get about a 500 rpm drop when it locks up.

Before you start chasing the transmission, check the ECT. http://web.archive.org/web/201003261...98engineco.pdf By design, the transmission won't lock-up when the engine is cold; a bad ECT could prevent lock-up. Remember that your A340H has built-in diagnostics; http://web.archive.org/web/201408161...31diagnosi.pdf . They won't tell you of a slippy lock-up clutch, but it will detect a dead solenoid.

rworegon

Since this may be in response to my post, I have edited it for clarity. I was trying to say just skip the built-in cooler and use only the external cooler, but certainly do not go without any tranny cooler. Heat is the big enemy of auto tranny's.

Marc

On mine a few seconds after it goes into 4th the converter locks up and it drops another 500 rpm approximately if I'm cruising at a steady speed.

If you don't get the slight drop it's probably not locking up.

If I give it the slightest bit of gas it will unlock.
It's easy to see how it works when the cruise control is on.

pplusent

there are no codes, just the OT warning lite. There is an rpm drop of 500 when the 4th gear kicks in. all the shifting is smooth as silk, just seems like a lot of rpm at highway speed. the only other odd thing is it does not go into OT when cold, but then after about a 1/4 mile it works fine. I don't seem to have any slipping going on, but when I was climbing a steep hill in 4 wheel low it seemed to run out of power and slipped a bit, but that is the transfer case and the manual said to set the clutches at around .110 in clearance which I feel is to much. I just don't get the heat issue, it seems that it would have to be the converter or solenoid. the solenoid measured 13.4 ohms, but I did not do a leak check. I had a temp tranny in it while I rebuilt this one and it had almost 700 drop more than this one, but before I rebuilt this one it did the same rpms, so I am thinking since the sol and converter were reused and thay have had an issue that I missed. Of course you can't test a torque converter so it's hit and miss on that.

pplusent

Changed out the torque converter today and I am finally getting lock up.
Apparently Precision torque converters made some defective ones about to years ago and I ended up with one of them.
just my luck!!!
Thanks for all the input!!!

Marc

Glad you got it fixed.