Hey everyone, I have HCI with A4 stalled in 99 T/A, 4L60E. Stock diff with 3.73 gears and street tires.

Trans was rebuilt about 15 months ago with mildly upgraded parts. About 6 mos. ago my trans puked out a bunch of fluid, it was shifting strange one day on highway driving and I had to add at least 2 pints, I think a little more. It was fine for maybe 8 months prior to that and for 5 months after that. Never added a drop and shifted perfectly no slips. So just wrote it off.

Went on 300 mile round trip last week and about 200 miles into the drive it puked out all the fluid again. Was not WOT the entire trip, just normal accel for onramps etc.... It's misted all over the back of the car, lots of fluid, and I had to have the car towed. I added at least 4 pints (2 quarts) and it still didn't register on the dipstick, so it puked A LOT. Trans cooler was dry, both cooler lines dry all the way back to trans, they are wet at the trans but EVERYTHING is wet back there from fluid puke. I have a lift and tried but not able to see where leak is. Doesn't matter anyway because I don't trust it for my DD now so having trans rebuilt again.

Was not driving hard at all in the last several months (this car is DD), have not been to the track this year at all. Ran beautifully prior to the dump.

Main reason for my post is that the builder is suggesting my tune has the line pressure too high. Trying to get a rebuild at a discount because I think there was a problem in the original rebuild, and need to know if he's right. I feel like it was a mistake he made somehow.

So, is he full of craaap?

The current tune is based on an old Frost tune from years ago before I cammed it. It probably has whatever trans improvements Frost would do, but I can't imagine the tune is causing this problem. I think I did adjust shift points due to a different Torque Converter but I don't think I touched transmission areas at all, just MAF and IDLE and other things in the typical CAM tune recipes/howtos.

Input please? I'll throw some screenshots of the trans sections of my tune here shortly.

 

If the transmission fluid gets too hot... it will vent the fluid out.

I say this now to everyone who starts a thread.
Please go and check fluid level when idling hot in park, check line pressure for all gear ranges, check the operating temperature, and check for any DTCs.

 

Armed with this info and a little searching I think I have it figured out. My car was running hot all summer, to the point where I could not run AC while sitting in a long drive through restaurant for example or temps would start to trickle way above middle point on the gauge. The thread linked below describes how putting trans cooler right on radiator (AC condenser in my case) could actually overheat his transmission. It was a hot day and ran AC for hours probably overheating trans and dumping just like you describe. So it's my fault, which is cool because at least I know what caused it and can maybe trust the car (and the builder) again. will check codes to see if something's there to back up this theory. Any other ideas or theories I'd love to hear.

https://ls1tech.com/forums/automatic...t-does-do.html

 

Regardless of mods, it is extremely wise to have the ability to check your trans temperatures on a regular basis. I use an Aeroforce Interceptor ($$$) but it's an extremely nice piece of equipment to have. It plugs into the OBD port and gets the temp from the PCM, among numerous other readings.

There are several other options to track trans temp. Some people weld a bung in the pan and just buy a trans gauge. Its a common misconception on here though because the PCM reading is already from the pan.

If you want to go cheap, then I would start searching for a higher quality Bluetooth OBD adaptor. It will sync with an app on your phone that also doesn't cost much. The value in seeing trans temps is priceless, especially since you feel like yours has been overheated.

 

The problem is... we do not know why the transmission vented the fluid out.

I mentioned over-heating because it is common. I hope for your sake, this is the case here.
Also, why is it over-heating? ...Could it be; that an external transmission cooler is getting too hot from outside influences... yes, but other possibilities should also be investigated.

The most common reason that a 4L60E transmission over-heats... is due to the torque-converter clutch, not locking-up.

The shorts list of things that I posted should be checked.
A transmission that is over-heating will have its life-span reduced immensely!

An operating range of 160*F to 180*F would be ideal
Too cold; and there is a small amount of performance left on the table...
However, too hot; and the life of the transmission is cut-short.

The image below is an approximation of life expectancy reduction, based on fluid temperature:



As posted by Tyler; monitoring the transmission fluid temperate after the transmission is first installed, upgraded or modified, or during problems... Is very important.
It is best practice to simply install a permanent Transmission Fluid Temperature gauge with the sending unit in the oil pan.
I encourage everyone to do it!

I hope you are correct in your assumption of the cooler being super-heated.
Good luck!

 

I prefer having the sending unit in the return (top) line, going back to the transmission. This will give immediate temperature changes as compared to putting in the pan. Make what ever changes are needed to get the right temperatures 155F - 185F. When climbing a hill, it will get higher temperatures sometimes. However, it should come back into range quickly when leveling out. If the oil temperatures keep climbing, then manually back shift to third to prevent this. If it still keeps climbing, pull over and see what is going on here. You might have to add a thermostatically controlled fan to the external cooler to keep the temperatures in range.

 

Pressure doesn't make it pop out the vent. Well not on it's own anyway.
I've had these units over 270psi and never kicked any out the vent. If you saw where the vent is in the case, and how it works, you'd understand it's not an issue with pressure.

With that said, increased pressure will increase heat. As will a loose converter. As will a converter that is not getting 100% lockup.

Temp, foamed fluid, and over-filled transmissions are the reasons for it to kick out the vent.
Since it took a while for yours, I'm leaning towards temp

 

Thanks for all the input everyone!

I have not yet pulled the transmission, I didn't bother testing or anything to see if I did damage because I was going to yank it and have it rebuilt because I didn't understand what happened and I didn't trust it.

But now that I *think* I have an idea of what happened, I will instead be doing the following and see if I can save a transmission rebuild:

1) get to where I can monitor transmission temperatures. I already have an ELM scanner and use it on my Chevy SUV when I tow (Torque app with special PID or something), so pretty sure I'll have this already. If not I suspect my hptuners can do this. I also have a tech II clone until I get a more permanent solution. I'm sure I monitored trans temps in the past with this car just probably not on a hot day running AC for hours.

2) move the cooler far away from the hot condensor/radiator.

3) drain all old fluid and replace, and see if trans is damaged and see if temps stay reasonable and just see what happens.

Thanks again!!! I've had 6 fbody cars and untold amount of mods/repairs all thanks to the continual learning from those in the ls1tech community!

 

I have another theory to add quick... you have the trans cooler on the condenser? Is it standalone or are you running it with the radiator "cooler"?

 

I do not run the aftermarket cooler in parallel to the factory one, it is standalone because when my last transmission went kablooey I didn't trust that there wasn't debri in the factory cooler, so bypassed it and just ran a new aftermarket cooler only.

The current aftermarket cooler is about 6" high and maybe 15" wide and was placed right on the AC condensor (radiator-like thing) somewhat lower leftish in the front with only super thin rubber grommets that came with the cooler between it and the condensor, and had ziptie type connection through the vanes. I do remember when I was installing it to route the flow path the right direction, not sure if that matters.

 

When I had my trans cooler mounted on the condenser, the coolant ran way hotter than it did prior. Once I moved it, my coolant temps dropped a good amount. This seriously cut down my coolant temp 25-30 degrees. I also have the SSRA so I really killed some airflow. Even without SSRA I guarantee you'll see a coolant temp drop by getting it off the condensor.

Also, I had better luck bypassing the stock cooler in the radiator. I run a tube and fin cooler, and a stacked plate. I'm sure some have ran 2 stacked plate coolers but I was a little concerned about fluid flow. Both are under the car and see a lot of air movement.

So in summary, having remote standalone coolers cut down my coolant temps AND trans temps. This is what I recommend.

Just thought of something else... when I bought my car over a decade ago, it never had the bottom air deflector/dam. Its the long black plastic piece on the radiator support. After adding that my temps dropped even further for coolant temps. Its not uncommon for someone to remove one because it broke or because they kept scraping it. Make sure yours is there as it is very valuable to have.

 

I just noticed you said that you ran hot while sitting and not cruising... still make sure you have the deflector but since you are not moving and its getting hot I would verify the fans work properly. Also, I wouldn't trust the temp gauge in the cluster one tiny bit. I have a 98 (suppose to be more accurate than the newer cars) and its hilariously off. Another huge benefit of having an interceptor or another way to display actual engine temp. I leave my interceptor screen on trans temp and coolant temp 99% of the time. Both are invaluable.

 

UPDATE: Radiator was super dirty and looked horrible so swapped radiator (factory trans cooler was contaminated as well, another reason to replace), evacuated all the fuid I could from trans dipstick tube, and filled everything back and it now is running fine while running trans fluid ONLY through factory radiator trans cooler this time. Removed aftermarket cooler, it was not plugged or anything. Trans fluid did not stink but was very dark red instead of cherry red. Trans does seem to run a little hot but it's only being cooled by 220 * coolant (in slow traffic situations) so I think that's normal for now. Shifts perfectly, TC lockup is perfect, no slipping under load in any gear.. Will be monitoring it with my torque app and my ELM bluethooth scantool.

ALSO, this might be important for not only me but other people with overheating transmissions... .I know I've had a somewhat low charge in my A/C because it would do the COIL FREEZE thing once in a while where the components inside the car would apparently freeze up and block blower airflow, I'd have to turn off the A/C to let it thaw and restore airflow, the reason I believe it was freezing because the air was mostly coool even without the AC on while "thawing", and I also see low charge with my manifold set... BUT....

COULD IT BE that running A/C in this icing-up condition also causes the condensor (the radiator thing) to get super hot? This would explain the superheating of my transmission because my aftermarket cooler was tied right up against it with just spongy thin grommets between the two.

I see so many people with aftermarket coolers tied to this condensor having unexplained high temps AND high trans temps with A/C running, I wonder if this could be a main cause?

I should have just did the trans fluid swap and left the other stuff alone and tested this theory with my IR temp gun..

Any A/C pros out there want to chime in? Does a low AC charge cause condensor to get super hot when the interior part gets too cold?