A340F Trans Leak

[clearock]

hopefully u just didn't set the TQ fully into place... u really have to wiggle them back and fourth to match up all the splines and then when installing be careful shit doesn't slid forward when ur getting the trans into place. u can usually just slid the unit back after unbolting all the housing bolts and set the TQ down fully. if u have to use the housing bolt to pull the engine and trans together that would be a major clue the TQ wasn't fully engaged. if u know all this then disregarded the above.

cant tell from the pic if they r casting lines or if ur flex plate is cracked.... (missed the part where u said u replaced said... and jumped to the main body of ur post...)

 

[AssBurns]

hopefully u just didn't set the TQ fully into place... u really have to wiggle them back and fourth to match up all the splines and then when installing be careful shit doesn't slid forward when ur getting the trans into place. u can usually just slid the unit back after unbolting all the housing bolts and set the TQ down fully. if u have to use the housing bolt to pull the engine and trans together that would be a major clue the TQ wasn't fully engaged. if u know all this then disregarded the above.

cant tell from the pic if they r casting lines or if ur flex plate is cracked....

Not too sure what the deal was. I pulled the trans a second time and made sure the TC was fully seated. It may have been but I made sure again and bolted it all up. It went together smoothly besides the TC being tight against the flexplate not allowing me to spin things separately to line the bolt holes up. I ended up loosening the trans and pulling the trans back about 1/4" to allow some room to work. Ones I got the bolts lined up and threads engaged I tightened the bell housing bolts again. Worked out good and no more leaks. Sucks that my new torque converter didn't come in before the weekend (should be here tomorrow). I was really looking forward to getting it in there before my trip later this week.

The flex plate was definitely cracked. I thought I had a lifter tick but turns out it was just a cracked flex plate.

 

[Timmah!]

Not too sure what the deal was. I pulled the trans a second time and made sure the TC was fully seated. It may have been but I made sure again and bolted it all up. It went together smoothly besides the TC being tight against the flexplate not allowing me to spin things separately to line the bolt holes up. I ended up loosening the trans and pulling the trans back about 1/4" to allow some room to work. Ones I got the bolts lined up and threads engaged I tightened the bell housing bolts again. Worked out good and no more leaks. Sucks that my new torque converter didn't come in before the weekend (should be here tomorrow). I was really looking forward to getting it in there before my trip later this week.

The flex plate was definitely cracked. I thought I had a lifter tick but turns out it was just a cracked flex plate.

I have heard one issue with flex plates cracking is due to missing the alignment dowels on the back of the engine block. If those stay attached to the old transmission and you don't realize it and put in the replacement transmission without the alignment dowels, there can end up being a slight misalignment of the trans and engine, even though the bolts all line up and are torqued to spec. The misalignment can cause excessive pressure on the flex plate causing it to crack.

 

[AssBurns]

I have heard one issue with flex plates cracking is due to missing the alignment dowels on the back of the engine block. If those stay attached to the old transmission and you don't realize it and put in the replacement transmission without the alignment dowels, there can end up being a slight misalignment of the trans and engine, even though the bolts all line up and are torqued to spec. The misalignment can cause excessive pressure on the flex plate causing it to crack.

Hmmm... I will have to look at pictures and see if there were any missing alignment dowels. I think there were but I can't remember for sure. Good to know.

 

[andresabbott]

hopefully u just didn't set the TQ fully into place... u really have to wiggle them back and fourth to match up all the splines and then when installing be careful shit doesn't slid forward when ur getting the trans into place. u can usually just slid the unit back after unbolting all the housing bolts and set the TQ down fully. if u have to use the housing bolt to pull the engine and trans together that would be a major clue the TQ wasn't fully engaged. if u know all this then disregarded the above.

cant tell from the pic if they r casting lines or if ur flex plate is cracked.... (missed the part where u said u replaced said... and jumped to the main body of ur post...)

hi, sorry for this old thread..

im having the same issue. leaking oil trough the bell housing.. it only happens when the trans got to the operating temp and when i push the car hard... when the car is not running, or only running without running there isnt leak.. This happend after i did a hard rally/off road/ event.. maybe i overheated the trans? maybe is only the front seal? im worry about this. Can anybody help me with the diagnosis?

 

[clearock]

hi, sorry for this old thread..

im having the same issue. leaking oil trough the bell housing.. it only happens when the trans got to the operating temp and when i push the car hard... when the car is not running, or only running without running there isnt leak.. This happend after i did a hard rally/off road/ event.. maybe i overheated the trans? maybe is only the front seal? im worry about this. Can anybody help me with the diagnosis?

not being there I can't properly diagnose, the 1st thought I have is ur front pump seal where the TQ fits into said. When ur getting the trans up to temp then fluid thins and would make it easier to get by the seal, in addition, there trans c's high internal pressures/heat when "I push the car hard" which would also help fluid get passed the seal. That said the OEM seal are very robust and unless u have high miles on the car are repeatedly heating the unit and contributing to the seal harden/brittleness..... could also be pump wearing out etc. When u say things like "hard rally/off road/event", its clear u don't baby ur car and those activities equal highly accelerated rate of required maintenance. Sounds like u need to drop ur trans and take a closer look at the issue.

 

[snowtank]

Quick question as I'm seeing contradicting info. When you guys did a external trans cooler which way you hook up the return and exit lines? Or does it matter? Some saying exit line on the top and in line on the bottom and vise versa. Currently have it set up with in line up top and return down low. I haven't ran the truck yet as I just been doing other maintenance too. Just seeing what the general consensus is.

 

[4runner DOA]

Quick question as I'm seeing contradicting info. When you guys did a external trans cooler which way you hook up the return and exit lines? Or does it matter? Some saying exit line on the top and in line on the bottom and vise versa. Currently have it set up with in line up top and return down low. I haven't ran the truck yet as I just been doing other maintenance too. Just seeing what the general consensus is.

I wanna say when I did mine I went trans out to the upper line and lower line back to the trans. I just followed whatever instructions I found online.

 

[snowtank]

I wanna say when I did mine I went trans out to the upper line and lower line back to the trans. I just followed whatever instructions I found online.

OK you did what I saw Timmy do. I followed rameriz write up on it. I don't think it matters but with inclines I'm afraid of sucking air out of the top side. Maybe over thinking it

 

[4runner DOA]

OK you did what I saw Timmy do. I followed rameriz write up on it. I don't think it matters but with inclines I'm afraid of sucking air out of the top side. Maybe over thinking it

I filled the trans cooler and as much as I could of the lines before tightening things down. I knew my atf levels were good because I did a drain/refill + check before adding the cooler. I don't think some air will hurt, but I'm not a mechanic. Haha.

 

[thezentree]

Shouldn’t the ATF in the cooler circuit be under enough pressure that there shouldn’t ever be any air in the line if your transmission has the correct amount of ATF in it?

 

[clearock]

I filled the trans cooler and as much as I could of the lines before tightening things down. I knew my atf levels were good because I did a drain/refill + check before adding the cooler. I don't think some air will hurt, but I'm not a mechanic. Haha.

Sucking air is not good at all and will slowly kill the auto trans, there r a few examples of OEM "mistakes" that highlight said, the 90's model Ford Taurus is an example (the oil pan was to large for the OEM filled lvl on the deep stick so every time it went around a corner the trans pump would suck air and burn out the trans), this was fixed by over filling the unit by 4qts if memory serves.

Shouldn’t the ATF in the cooler circuit be under enough pressure that there shouldn’t ever be any air in the line if your transmission has the correct amount of ATF in it?

Unless ur mounting the oil cooler above the trans u r correct (should add the "above" would have to b by a lot, just going over the height of the trans by a bit shouldn't b an issue if ur already adding extra fluid for the trans cooler), if u mount the cooler to high the fluid will drain down back into the trans the vehicle is turned off and when u restart all the cooler vol would have to be refilled and until said is accomplished u'd b pushing air...

 

[Stairgod]

Sucking air is not good at all and will slowly kill the auto trans, there r a few examples of OEM "mistakes" that highlight said, the 90's model Ford Taurus is an example (the oil pan was to large for the OEM filled lvl on the deep stick so every time it went around a corner the trans pump would suck air and burn out the trans), this was fixed by over filling the unit by 4qts if memory serves.

Unless ur mounting the oil cooler above the trans u r correct (should add the "above" would have to b by a lot, just going over the height of the trans by a bit shouldn't b an issue if ur already adding extra fluid for the trans cooler), if u mount the cooler to high the fluid will drain down back into the trans the vehicle is turned off and when u restart all the cooler vol would have to be refilled and until said is accomplished u'd b pushing air...

The tranny cooler will not gravity drain into the tranny unless a line is cracked.
I have had a few vehicles with a tranny cooler mounted as high as the top of the radiator. There is always fluid and just fluid in the cooler and the lines at all times.
Depending on the transmission in question it is either a non-bypass type pump or there is a check(anti-drainback)valve installed to prevent any fluid movement with the engine not running.

 

[Stairgod]

Quick question as I'm seeing contradicting info. When you guys did a external trans cooler which way you hook up the return and exit lines? Or does it matter? Some saying exit line on the top and in line on the bottom and vise versa. Currently have it set up with in line up top and return down low. I haven't ran the truck yet as I just been doing other maintenance too. Just seeing what the general consensus is.

If the cooler has a thermostat or bypass circuit in it the the inlet and outlet on the cooler are clearly marked. I had a Derale cooler like that.
Otherwise it doesn't matter to the cooler which way the fluid goes through it.

 

[snowtank]

If the cooler has a thermostat or bypass circuit in it the the inlet and outlet on the cooler are clearly marked. I had a Derale cooler like that.
Otherwise it doesn't matter to the cooler which way the fluid goes through it.

Yeah it's not marked in/out/top/bottom. So just kinda guessing and seeing what everyone else is doing. I added a half quart to make it "full" . Then realized I don't know when the last time a trans flush was done so decided to stop adding and just do a full flush of the system.

Thanks for all the replies everyone! I appreciate all the help!

 

[clearock]

The tranny cooler will not gravity drain into the tranny unless a line is cracked.
I have had a few vehicles with a tranny cooler mounted as high as the top of the radiator. There is always fluid and just fluid in the cooler and the lines at all times.
Depending on the transmission in question it is either a non-bypass type pump or there is a check(anti-drainback)valve installed to prevent any fluid movement with the engine not running.

Ty 4 responding and if u can expound "non-bypass type pump or check (anti-drainback) valve in the A340. I have dismantlement a # of said) and there's no "check (anti-drainback) valve, so r u saying its the front pump that acts like having ur finger over the top of a straw filled with a liquid which would stop gravity drain if the cooler is placed to high???

This is the rear return hole and fluid flows unobstructed back into the pan


this one is the front cooler line

 

[thezentree]

I'm just going to assume that you spent all morning tearing down your transmission just to prove a point and didn't go look in your spare parts pile in the garage. I like that story better.

 

[Stairgod]

Ty 4 responding and if u can expound "non-bypass type pump or check (anti-drainback) valve in the A340. I have dismantlement a # of said) and there's no "check (anti-drainback) valve, so r u saying its the front pump that acts like having ur finger over the top of a straw filled with a liquid which would stop gravity drain if the cooler is placed to high???

This is the rear return hole and fluid flows unobstructed back into the pan
View attachment 82581View attachment 82582View attachment 82583

this one is the front cooler line
View attachment 82584

Haven't ever had one of those apart, but yes I am saying that the pump is what keeps the fluid from draining out.
The type of pump obviously determines if a check valve is needed or not.
Fin style pumps for hydronic heating systems for instance require an internal check valve so that you don't end up with unwanted convective flow.

 

[clearock]

I'm just going to assume that you spent all morning tearing down your transmission just to prove a point and didn't go look in your spare parts pile in the garage. I like that story better.

yeah started last night to pull my trans to tear it down this morning....

No point to be proven, just after a better understand of how the system works to I can tweak and push the trans limits to work as needed, thankful @Stairgod was willing to school me so I do not spread that misinformation. Now I have to read up on "non-bypass type pumps" to get a clearer understanding of said.

 

[Stairgod]

I always assume that what I say is clear. However history has taught me otherwise.
If I am wrong or someone does not understand what I say I can usually go into more detail. I seldom open my mouth without knowledge, unless of course you ask my wife.