A340F Trans Leak

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA
Well this isn’t something I was expecting to have to deal with right now. My trans is leaking a ton from the bell housing. Going on a trip in two weeks and need to figure this out ASAP.
I know I’ll likely need to pull the trans to fix whatever is causing the leak.
Assuming I’ll need to order parts, what should I be prepared for to fix on this?

 

4runner DOA

Hold my beer
Staff member
Joined
Oct 2, 2018
Messages
15,882
Location
OC
Well this isn’t something I was expecting to have to deal with right now. My trans is leaking a ton from the bell housing. Going on a trip in two weeks and need to figure this out ASAP.
I know I’ll likely need to pull the trans to fix whatever is causing the leak.
Assuming I’ll need to order parts, what should I be prepared for to fix on this?


Transmission jack if you don't have one would help. Drop the transmission and figure out which seal is letting loose?
 

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA
Transmission jack if you don't have one would help. Drop the transmission and figure out which seal is letting loose?
Yep, that's the plan. I need a trans jack anyway so this is a good excuse to buy one now. Hoping it's something easy like a seal that takes two minutes to swap (once the trans is pulled).
Worst case torque convertor
Best case, and most likely, front seal on the trans. Trans jack, swearing and some beers.
I am looking into replacement torque converters right now. I want a higher stall speed so this is a good time to swap in a new TC while the trans is out. I am waiting for a call back from a tech at Level10 to see if they have a recommendation for a good stall speed. From what I could find, stock is about 2200rpm (attached is a spec sheet from toyota I found). I also found a dyno sheet from AFE that shows a stock 5vz-fe. Looks like these don't start getting into the torque band until about 3000rpm. I'm thinking I'll want a stall speed around there to get the most of it but I'd like to speak to a professional before I commit. I may need to add another large trans cooler if I go this route.

 
Joined
Dec 1, 2020
Messages
404
U sure its coming from the bell housing and not the vent on the top side of said? Is it leaking all the time (ie cold start up or after u've pushed the 4runner hard)? Probably the front seal but dont usually c them leaking that bad unless something else has helped take the seal out, ie someone not tightening up the TC bolts after pulling the trans/engine for some reason, the front trans pump has excessive play. if the front pump is going out u could have been hearing a whining noise??? but not always, u could need to replace the front pump and TC if damage has accursed and if so I'd replace the pump with one from another A340 with the taller pump to flow more fluid, but until u pump the unit we can all speculate on and on, as it could just be the front seal but exp tells me most likely the leak/seal is a symptom of something else...
 
Joined
Dec 1, 2020
Messages
404
I may need to add another large trans cooler if I go this route.
one of the better mods I did to my trans was to add an idiot light to my dash to signal TC lockup and adjusted driving around said to reduce trans temps, as the TC adds tons of heat to the system
 
Last edited:

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA
U sure its coming from the bell housing and not the vent on the top side of said? Is it leaking all the time (ie cold start up or after u've pushed the 4runner hard)? Probably the front seal but dont usually c them leaking that bad unless something else has helped take the seal out, ie someone not tightening up the TC bolts after pulling the trans/engine for some reason, the front trans pump has excessive play. if the front pump is going out u could have been hearing a whining noise??? but not always, u could need to replace the front pump and TC if damage has accursed and if so I'd replace the pump with one from another A340 with the taller pump to flow more fluid, but until u pump the unit we can all speculate on and on, as it could just be the front seal but exp tells me most likely the leak/seal is a symptom of something else...
Hard to tell. It just started leaking while I was out playing in the dirt yesterday. Could be the vent the reason I think that might not be the case is because I let the truck sit for about 20 minutes after parking it and it was still leaking quite a bit right away. Makes me think it isn't the vent when it is low on fluid and not as hot.
I don't notice any whining noises but also didn't listen for it either.
I am most likely going to get a new TC so either way that should eliminate that potential issue.
The motor was replaced at one point so there is a chance the mechanic didn't torque things down enough and things got loose. Or could be from me railing on the truck constantly...
one of the better mods I did to my trans was to add an idiot light to mt dash to signal TC lockup and adjusted driving around said to reduce trans temps, as the TC adds tons of heat to the system
That's a good idea. I want to add a temp gauge too. Could we add a manual lockup switch to these? That would be a nice feature to have in traffic situations.
 
Joined
Dec 1, 2020
Messages
404
let the truck sit for about 20 minutes after parking it and it was still leaking quite a bit right away
20 to 30 mins after stopping is when the vehicle temps will will b at their peak, got to reminder that theres no air or pump flow after u stop to help cool everything down...
imo the a340 version in the 3rd gens don't handle larger tires and weight as they sit OEM but there r a # of mods that can make handle said. I forget what yr ur runner is but I prefer the 99-02 ecus at u have the trans temp in OBD2 data stream which allows u to monitor said. It sounds to me like u overheated the tans and it was most likely venting, u can easily confirm by starting the unit after its sat over night and cooled completely down and if ur still pour fluid then I'd look at the front seal and if not then u probably pushed it to hard and vented.
Could we add a manual lockup switch to these?
Yes u can, I have a switch hooked up to a dead man switch that I use at times, but the fins in the TQ that engage lock up r not very robust and u can damage ur TQ if u don't force lockup "safely", the TQ CANNOT b in lock up when coming to a stop or when ur punching the gas, the ECU can tell when lockup is happening out side of its control and will completely disable normal lockup outside of forced and u have to turn of the vehicle and restart for norm ecu contol of said.
 

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA
20 to 30 mins after stopping is when the vehicle temps will will b at their peak, got to reminder that theres no air or pump flow after u stop to help cool everything down...
imo the a340 version in the 3rd gens don't handle larger tires and weight as they sit OEM but there r a # of mods that can make handle said. I forget what yr ur runner is but I prefer the 99-02 ecus at u have the trans temp in OBD2 data stream which allows u to monitor said. It sounds to me like u overheated the tans and it was most likely venting, u can easily confirm by starting the unit after its sat over night and cooled completely down and if ur still pour fluid then I'd look at the front seal and if not then u probably pushed it to hard and vented.

Yes u can, I have a switch hooked up to a dead man switch that I use at times, but the fins in the TQ that engage lock up r not very robust and u can damage ur TQ if u don't force lockup "safely", the TQ CANNOT b in lock up when coming to a stop or when ur punching the gas, the ECU can tell when lockup is happening out side of its control and will completely disable normal lockup outside of forced and u have to turn of the vehicle and restart for norm ecu contol of said.
What’s weird is that I wasn’t driving very hard to heat up the trains a lot. A lot of it was downhill for the last 10 miles or so. I do have a large transmission cooler that really helped when I first got it. I don’t see how the trains would be overheating that much. The temp light never kicked on either. How much fluid can really get pumped out of the vent when heating up? It was a lot of fluid lost.
 
Joined
Dec 1, 2020
Messages
404
unfortunately the trans temp light doesn't turn on until well after temps required for the fluid to start coming out of the vent. u can loose "a lot" as it pukes fluid out... but as I was not there I am just throwing out what I can based on what little info I have to try and help. On the good side if u did overheat it one time these r very robust trans and I would just replace the fluid and move forward with a temp gauge and what every other mod u want to take the time to install and ur trans is probably fine
 

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA
unfortunately the trans temp light doesn't turn on until well after temps required for the fluid to start coming out of the vent. u can loose "a lot" as it pukes fluid out... but as I was not there I am just throwing out what I can based on what little info I have to try and help. On the good side if u did overheat it one time these r very robust trans and I would just replace the fluid and move forward with a temp gauge and what every other mod u want to take the time to install and ur trans is probably fine
I was in the area and came home to see if it’s still leaking when cold. It’s not leaking a lot but it still has a very light drip. As it’s warming up more it’s leaking a little faster. It’s been idling for about five minutes or so. I assume it’s not fully up to temp yet and it’s already leaking a drop every 15 seconds or so.
 

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA
I assume the vent is at the top of the transmission somewhere?
I don’t see any trans fluid more than half way above the bell housing.
 

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA
OK yeah, it’s definitely not coming from the breather. It seems to be dripping from the bottom of the bell housing only.
Hopefully it’s just the seal. Either way I just ordered a new torque converter. The guy told me that a stall speed about 500 RPM higher than stock is probably the best way to go for my use. He said they’ve ran these trucks at higher RPM and they just generated more heat with a little gain. If I find it too low I can always get it sent back and modified. I’m sure it’s gonna be a huge improvement over stock without too much added heat.
 
Joined
Dec 1, 2020
Messages
404
nice, these r great units to take the leap and pull apart and demystify the auto trans... while the trans is out u should shift kit VB and drill out the plate and throw in the taller front pump (I just pull them from the junk yard, u have to change out the snout that meshes with the TQ as the 8 cyl TQ or larger then the TQ found in the 3rd gen)
 

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA
nice, these r great units to take the leap and pull apart and demystify the auto trans... while the trans is out u should shift kit VB and drill out the plate and throw in the taller front pump (I just pull them from the junk yard, u have to change out the snout that meshes with the TQ as the 8 cyl TQ or larger then the TQ found in the 3rd gen)
Unfortunately more work than I expect to have time for at the moment but I do have a trans go shift kit in the garage waiting for me to find time to install.
 

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA

Airdog

Did Your Mom
Joined
Oct 5, 2018
Messages
543
While I am in there I plan to replace the motor mounts and transmission mount. I ordered the Trail Gear Bomb Proof Motor Mounts already. Does anyone know if someone makes a stronger transmission mount for the A340F? I know Trail Gear makes stuff for the early model 4runners and 4xInnovation makes one for the R150F, but I cannot find one for the A340F...
I know I could make one but limited time makes it harder than it's worth.
You check with solid_offroad on IG. My order ships tomorrow...like these but black.
Image1.jpg

These look like the right stuff ?
 
Last edited:

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA
You check with solid_offroad on IG. My order ships tomorrow...like these but black.
View attachment 76979

These look like the right stuff ?
Thanks man. I didn’t know this company existed.
I reached out to him but unfortunately he doesn’t make what I need. Luckily Caleb over at Hot Metal Fab makes a WIY kit that he’s gonna send over to me tomorrow.
 

AssBurns

will wheel for beer
Staff member
Joined
Oct 1, 2018
Messages
7,959
Age
31
Location
Yucaipa, CA
So here’s my flex plate. Makes sense why the seal went bad. Stole Roberts off his since his trans was already off.

So the issue I’m having now is that the flex plate is too tight against the TC (not wanting to rotate freely/separately)
Did I not seat the TC all the way in when installing?
I assume I’ll have to pull the trans again which sucks balls.

D7DD0450-D4FC-4B84-A411-0B61DC4A20DC.jpeg
 
Top Bottom