A343F trans fun

[3FOffroad]

I’ve done my best to search abs read through all the trans threads I could find. Good/bad. Good is this is a damn good transmission. bad is I can’t find someone with similar issues.

here is goes. I have a 97 cruiser with 212k miles. When vehicle starts up and takes its first 15 miles it shifts very harsh and jumps up and down in shifting erratic. No noises. It also is sluggish off the line for that first take off.

fluid is full abs clean and I have done a few drain and replaces. It isn’t an issue where it is just cold as I can start the rig and leave it running for 20 min and still the same issue.

No lights on the dash

reverse is good

After that first 15 miles is in it runs great from that point on. Even if sitting for a few hrs and back to cold temps.

As I’m new to this trans I’m wondering if anyone has had issues with drainback. I’m thinking that as the truck sits for a longer period the converter is draining back which could cause the issues.

reminds me of the old Chrysler trans that had a drain back issue like this... or I could just be grasping for straws here.

Any thoughts?

 

[3FOffroad]

One thing I haven’t done is check the fluid after the issues stop having. That could point me in the right direction if it is a drain back issue.

Did some digging online and valve kits for the trans which makes me think this would be an unlikely issue. Sonnax usually has a fix available if there is one out there.

 

[cjmoon]

If it was drain back fluid would be airated and have air bubbles whine noise heat would make it worst. Have you done a pans filter drop? Torn gasket? Sucking in air till warm. Expansion seals it up?

 

[3FOffroad]

If it was drain back fluid would be airated and have air bubbles whine noise heat would make it worst. Have you done a pans filter drop? Torn gasket? Sucking in air till warm. Expansion seals it up?

Great thought! I have not dropped the pan. I am taking a fluid sample in to work tomorrow to try and get some more info with that. I’ll drop the pan next. How difficult is it to get the pan back to flat to install? Any gaskets recommended?

 

[Kernal]

Is this a new problem? Did it start after the outside air temperature turned cold?? Are you sure the fluid level (and type) is correct; fully warmed up after 20-30 minutes of driving, check the level carefully (level ground, engine idling, shifter in Park,---)??

 

[cjmoon]

Is this a new problem? Did it start after the outside air temperature turned cold?? Are you sure the fluid level (and type) is correct; fully warmed up after 20-30 minutes of driving, check the level carefully (level ground, engine idling, shifter in Park,---)??

yes agree with this also fluid expands as it heats up. I actually over fill mine about a 1/2 quart. mine runs cool and on some angles I pick up air randomly when i shift from Reverse to drive and a couple second delay.

 

[3FOffroad]

Is this a new problem? Did it start after the outside air temperature turned cold?? Are you sure the fluid level (and type) is correct; fully warmed up after 20-30 minutes of driving, check the level carefully (level ground, engine idling, shifter in Park,---)??

New problem for me as it’s a new to me 80. Doubting it was new to the PO.

I will get a fluid check after running strong and see where it comes out.

I pulled a sample of the oil from the original drain, dark in color but doesn’t smell burnt. and we are running it through a particulate filter now to see what kind of contamination we might have.

 

[flintknapper]

I doubt TC drain back is the issue, its not a known problem with this transmission. I would be looking to a 'sticking' valve body.

You can check for TC drain back by checking your fluid levels. Take the vehicle for a drive until it shifts normally and is warmed up. Park on a level spot and check the dipstick. Make careful note of the level. Then let the vehicle sit overnight (or longer) and check the vehicle COLD (engine off). IF the level is significantly higher....then you have drainback from someplace, but remember a certain amount of drainback (not from the TC) occurs anyway... and is normal.

I would drop the pan, inspect the bottom of the pan (and magnets) for any appreciable metal particles or other debris.
Clean the screen. Bump up your line pressure while you are in there (no tools required). Button it back up, refill and take for a spin. IF the increase in line pressure doesn't overcome any sticky/leaking valves in the body....then it might be time to pull it and go through it.

The A343F is a wonderfully reliable transmission and with the exception of needing shift solenoids at times.....normally gives good service well past 200 K miles (with maintenance). I have 320K on mine with never an issue.

Double check your kick down cable too.

 

[3FOffroad]

I doubt TC drain back is the issue, its not a known problem with this transmission. I would be looking to a 'sticking' valve body.

You can check for TC drain back by checking your fluid levels. Take the vehicle for a drive until it shifts normally and is warmed up. Park on a level spot and check the dipstick. Make careful note of the level. Then let the vehicle sit overnight (or longer) and check the vehicle COLD (engine off). IF the level is significantly higher....then you have drainback from someplace, but remember a certain amount of drainback (not from the TC) occurs anyway... and is normal.

I would drop the pan, inspect the bottom of the pan (and magnets) for any appreciable metal particles or other debris.
Clean the screen. Bump up your line pressure while you are in there (no tools required). Button it back up, refill and take for a spin. IF the increase in line pressure doesn't overcome any sticky/leaking valves in the body....then it might be time to pull it and go through it.

The A343F is a wonderfully reliable transmission and with the exception of needing shift solenoids at times.....normally gives good service well past 200 K miles (with maintenance). I have 320K on mine with never an issue.

Double check your kick down cable too.

View attachment 2513140
View attachment 2513141View attachment 2513142

Awesome feedback! Thanks so much! I plan to drop the pan this weekend and will report back on what I find. What gasket, fluid do you recommend? Thanks again for the great response and the awesome pictures! Very beneficial!

 

[3FOffroad]

I doubt TC drain back is the issue, its not a known problem with this transmission. I would be looking to a 'sticking' valve body.

You can check for TC drain back by checking your fluid levels. Take the vehicle for a drive until it shifts normally and is warmed up. Park on a level spot and check the dipstick. Make careful note of the level. Then let the vehicle sit overnight (or longer) and check the vehicle COLD (engine off). IF the level is significantly higher....then you have drainback from someplace, but remember a certain amount of drainback (not from the TC) occurs anyway... and is normal.

I would drop the pan, inspect the bottom of the pan (and magnets) for any appreciable metal particles or other debris.
Clean the screen. Bump up your line pressure while you are in there (no tools required). Button it back up, refill and take for a spin. IF the increase in line pressure doesn't overcome any sticky/leaking valves in the body....then it might be time to pull it and go through it.

The A343F is a wonderfully reliable transmission and with the exception of needing shift solenoids at times.....normally gives good service well past 200 K miles (with maintenance). I have 320K on mine with never an issue.

Double check your kick down cable too.

View attachment 2513140
View attachment 2513141View attachment 2513142

I’m also assuming this is like a typical Toyota that uses the crazy strong sealant on the pan, if that’s the case usually don’t end up with a flat pan rail.

 

[flintknapper]

Awesome feedback! Thanks so much! I plan to drop the pan this weekend and will report back on what I find. What gasket, fluid do you recommend? Thanks again for the great response and the awesome pictures! Very beneficial!

Yes, unfortunately IF the pan has never been dropped (many have not) you will find the original (orange) FIPG in place. You'll need to cut (as best you can) the FIPG all the way around the pan before trying to pry the pan loose. It will be on there 'tighter than bark on a tree', just so you know what to expect.

Since you don't yet know the condition of the transmission.....I would refill it with the inexpensive WalMart brand of DEX3 or higher (I believe they are all backwards compatible). Then IF your problem is solved.....do a few drain and fills (over time) with a better grade (though all must meet minimum standards).

It's your choice for a pan sealant (FIPG), keeping in mind you may or may not be right back in there. IF I weren't planning opening it up again anytime soon, I'd use the Toyota recommended product.

 

[3FOffroad]

Yes, unfortunately IF the pan has never been dropped (many have not) you will find the original (orange) FIPG in place. You'll need to cut (as best you can) the FIPG all the way around the pan before trying to pry the pan loose. It will be on there 'tighter than bark on a tree', just so you know what to expect.

View attachment 2513157

Since you don't yet know the condition of the transmission.....I would refill it with the inexpensive WalMart brand of DEX3 or higher (I believe they are all backwards compatible). Then IF your problem is solved.....do a few drain and fills (over time) with a better grade (though all must meet minimum standards).

It's your choice for a pan sealant (FIPG), keeping in mind you may or may not be right back in there. IF I weren't planning opening it up again anytime soon, I'd use the Toyota recommended product.

Thanks! Yes, I know all to well about the Toyota sealer. We’re I work build some of their units but not the 393. Almost always had to install new pans due to having to pound them to get off.

Great news is just checked the micron filter and looks to be no contamination in the fluid... will no more once looking at the magnet in the pan.

I like your plan to the fluid.

I’m also planning to load up my transmission quality guys abs take them on a drive tomorrow to get a better idea on diagnosis.

 

[flintknapper]

Thanks! Yes, I know all to well about the Toyota sealer. We’re I work build some of their units but not the 393. Almost always had to install new pans due to having to pound them to get off.

Great news is just checked the micron filter and looks to be no contamination in the fluid... will no more once looking at the magnet in the pan.

I like your plan to the fluid.

I’m also planning to load up my transmission quality guys abs take them on a drive tomorrow to get a better idea on diagnosis.

Should be 3-4 small magnets in the pan, probably have some dark colored 'fuzz' on them which is normal. The pan on the 343 is pretty thick and if you score the FIPG (best you can) all around then pry on the CORNERS to break the seal its unlikely you'll bend it. Don't wail on it with a rubber or dead blow hammer, pry it off. You'll be fine.

 

[3FOffroad]

Should be 3-4 small magnets in the pan, probably have some dark colored 'fuzz' on them which is normal. The pan on the 343 is pretty thick and if you score the FIPG (best you can) all around then pry on the CORNERS to break the seal its unlikely you'll bend it. Don't wail on it with a rubber or dead blow hammer, pry it off. You'll be fine.

Thanks so much!

 

[3FOffroad]

So... loaded up the cruiser with some guys that do this for a living and I have a misfire. It comes in at 1500-1800 rpms once rig has sat for a few days. Once you push through that it doesn’t happen until you let it sit for awhile again. Hooked up scanner and nothing shows during the misfire. Thinking it’s an injector. Thinking of using seafoam, checking MAF, and TPS per some suggestions I have received. Wires, plugs, etc all new Toyota.

 

[yknot123]

Yes, unfortunately IF the pan has never been dropped (many have not) you will find the original (orange) FIPG in place. You'll need to cut (as best you can) the FIPG all the way around the pan before trying to pry the pan loose. It will be on there 'tighter than bark on a tree', just so you know what to expect.

View attachment 2513157

Since you don't yet know the condition of the transmission.....I would refill it with the inexpensive WalMart brand of DEX3 or higher (I believe they are all backwards compatible). Then IF your problem is solved.....do a few drain and fills (over time) with a better grade (though all must meet minimum standards).

It's your choice for a pan sealant (FIPG), keeping in mind you may or may not be right back in there. IF I weren't planning opening it up again anytime soon, I'd use the Toyota recommended product.

Would second the fluid flush with the Walmart high mileage, solved our shifting problems. Would also recommend doing the power flush with the engine running and refill line from oil cooler disconnected method. This way you can see the fluid go from brown to red. We flushed about 2-3 large bottles through. Needs to be done probably any way.
I didn't want to put new parts in old fluid. Luck has it no parts needed and have one solenoid out of three.

 

[3FOffroad]

It is a misfire, but thank you guys for the info now that I have a great resources I’m going to still do the full flush on the trans and drop the pan while I’m at it and check the magnets for pierce of mind. Grateful for this forum!