snap-on

So ive got a dead A340H.

Ive done quite a bit of reading/searching/educating myself as this is the first time ive ever had an auto. (got a 5speed in my truck)

(short version)
Bought a 4runner, fixed some motor stuff (didn't touch the trans)

After i got it running i never had a problem with the trans. Pulled my popup ~200 miles round trip no real issues. (other than the old 3.0 is underpowered but who doesn't know that)

I was coming up on a big CO trip and so i installed a trans temp gauge in a front cooler line, and did a half ass flush. (this is were i started to loose faith)

The fluid was brown and smelt of roasted walnuts. (NOT what i think of when i see red trans fluid) I thought, what the hell it worked fine before, and headed off for CO. My temp gauge seemed to run nice and cool 150-180 on the interstate, but got as high as 210 when i got into towns.

Once in CO it developed the problem i currently have which it doesn't accelerate. It did get me all the way back home with no problems.

Current symptoms, doesn't accelerate. (ive been known to drop it into 4 low so i can get moving to 20mph or so, then shift out) The truck shifts fine, the shifts seem to happen at the correct time, and are crisp(ish). OD button on/off and ill see a corresponding change in rpm when cruising at 60mph (ie its kicking in and out of OD)

What I've learned, Brown fluid = overheated and cooked. Heat comes from one place the Torque converter. so brown fluid = bad TC. this also makes since if we assume the TC is permanently locked up and im stuck with a 3 speed tranny with
1) - 2.8
2) -1.5
3) - 1.0
OD - .7

so no wonder it doesn't want to accelerate, its trying to start out in what would be (sorta) 2nd gear in my truck. (no wonder the engine bogs)

Once its moving (cruising on the interstate) it seems to accelerate fine and pull fine.

CONCLUSIONS.
1) i have a bad TC
2) the Valve body is fine
3) clutch packs are fine.

Solution, new TC and complete fluid flush should give me a good(ish) trans again.

question
Do you concur?

(ps, my research has told me that when the trans gets REALLY hot it will destroy the seals in the trans and it will leak, I have NO leaks of ANY kind)

Robinhood150

I don't know, but all I can say is that is some excellent detective work. Here's a bump for you and let us know what you find.

MTL_4runner

A few little tidbits for you to read:
http://personal.utulsa.edu/~nathan-b...28operatio.pdf
http://personal.utulsa.edu/~nathan-b...34electron.pdf

Lastly refer to page 15 on this one:
http://www.autoshop101.com/forms/h16.pdf

My bet is a solenoid is stuck, blocked or malfunctioning.
How does the truck accelerate if you manually shift through the gears?

snap-on

for got to add the bit about manually shifting,

no change. it doesnt accelerates any quicker, shifts when i shift the lever (asuming im going fast enough) and will also shift down on comand.

I thought the solenoids were responsable for individal gears, so if you had ONE Stuck or blocked it would work ok for 1 and 3 or 2 and 3 etc only the gear that the bad solenoid is repsonsable for is affect.

Based on that assumption ive tried to find a gear that worked better/worse than the others and have found none.

snap-on

oh and it shifts into 4hi on the fly like it should and from hi to low as expected.

(as this is a hydrolicly shifted transfercase version)

Oh and no weird noises to report, no winding, whir'n, squeeling, or otherwise\

Oh and reverse seems to have the same problems.

Oh and the delay times (haveing to do with the clutches) ie the lag time between between when you shift from N to D or N to R is correct at 1-2 sec per (i think it was the) FSM troubleshooting section

snap-on

I did have a mechinic suggest low fluid pressure, (which was covered in another post which i read)

why i dont think that is a problem
a) I would think it would not drive well at freeway speeds with such a problem (but it drives like normal, youd never know there was a tranny prob at 60-70 mph)
b) Seems like it would get hot quickly (which it does not, infact it seems to take much longer to get up to temp, ie the TC isnt spinning/slipping being the largest generator of heat)
c) fluid level has always been good, even from day one.

MTL_4runner

Are the rpms high on the motor while it is accelerating?
Assuming it was the torque converter, that should be getting VERY hot from slipping.

Are you sure it is an tranny problem and not and engine problem?

If you are sure the engine is fine then you may need to rebuild that tranny to actually uncover any issues it might have. Obviously something happened if the fluid was burnt like that.

Robinhood150

But if the TC is locked up all the time, it shouldn't generate much heat, right?

MTL_4runner

The solenoids work like a logic gate or like transistors (ie either on or off). Different combos give you different gears but only 2 solenoids (2 solendoids give you 4 different combos of on and off) operate all 4 gears (1st, 2nd, 3rd, OD) as I mentioned to look at the table on page 15. The other two solenoids are for converter lockup and 4wd engagement not gear shifts. If one solenoid is out then the table shows you what gears you would have.

snap-on

no, it bogs and hardly wants to rev from a dead stop. once your above 2500 rpm, in any gear, it seems to act normally, till it shifts then bogs again untill a) it downshifts again because I have my foot mashed on the floor, or b) it eventually gains enough speed that the rpm range moves out of the "bad" range (ie when the TC would normally be slipping and creating more torque for accelartion)

"Assuming it was the torque converter, that should be getting VERY hot from slipping."

that would be if it was slipping. I think its seezed up and NOT slipping at all. So the RPM that goes into the front, goes right out the back with out being changed.

Are you shure its a tranny prob? NO

but in trying to troubleshoot engine probs, is fairly easy.

1) is it smokeing (blown something) NO
2) does it rev right when in N YES
3) does it idle right (no vacume leak) yes , pluss the 4wd shifts fine (vacume shift)
4) have I run mulitipul tanks of gass through it (bad gas) YES
5) fluid levels check out good (oil level and pressure)

MTL_4runner

Hmmmm, now that is an interesting scenario and a good point.
Would the vehicle be very slow to accelerate in that case though?

MTL_4runner

I would check the solenoids for operation at the very least.....esp the converter lockup solenoid.

Robinhood150

Not sure, but I would imagine so. It wouldn't let the engine get to the higher RPMs where the power is. This also begs the question of whether he's blowing through all the clutch material (the bands or whatever) now.

MTL_4runner

I wonder how different the ratios on the auto are from a standard tranny. If the torque converter was locked like a clutch it should still pull unless the ratios are way off. My first check regardless would be to pull the pan, clean the filter and check each solenoid. If all still checked out fine and I was positive the tranny was at fault then I would start shopping for a used replacement.

Good timing:
https://www.yotatech.com/forums/showthread.php?t=67826

Might also have a look at this thread:
https://www.yotatech.com/forums/showthread.php?t=67826

You might also call John at IPT and see if he can help you pinpoint your problem.
http://www.importperformancetrans.com/

snap-on

Talked to john over at IPT, he seems to think its not a trans issue. more exahust (clogged cat) or fuel filter.

both are easy to check/clean/replace before i tackle that trans.

suppose ill start there.

Robinhood150

Did you get this resolved? I've been reading an auto transmission repair book and they explained torque converters. If the torque converter is stuck locked up, then you'd stall the engine when you come to a stop (or likewise, the truck would move when you hit the starter).

984RNR

any word

snap-on

not really, i decided id start with replacing the engine as it had a omoious knock that didnt sound good. It had 188K on it so it wasnt a spring chicken for a 3vze.

But the upshot is when i picked up the replacement engines i netted an extra A340H.

anybody want to trade a A340H for a R150F??

Im also in the process of trying to find a local trans shop that can bench test the torque converters (i have 2 now, that i have the org out of the 4runner) if that is even possible.

Babypig

why not try pulling the codes from the tranny and go from there. Same procedure as the engine just watch the o/d light instead and count the flashes. There is a lock up solenoid that could be the problem. The code will give you a good push in the right direction.

cmscott16

Your problems are the direct result of a freewheeling overrunning clutch in your torque converter. Basically, you no longer have the use of your stator, which sits inbetween your impeller and turbine and provides for torque multiplication in your torque converter. The stator redirects fluid in order to multiply torque during acceleration. It rotates on an overruning clutch that holds the stator stationary during acceleration. If this clutch fails, or your stator breaks, then you will have no acceleration until stall speeds or your lockup comes on. It is not repairable and you will need to purchase a new torque converter.