I’m stuck in a pickle and I’ve searched high and low for a fix to a similar situation without much luck. So I’m hoping someone on here might be able to help.

I have a LS2 swapped 69 Firebird with a 4l60e I recently finished putting together, which runs and drives great for about 10-15 miles and then problems arise.

My first longer drive in the car was to my folks house is about 15 miles away and about 3/4 of the way there and I could feel the car start to bog down a bit (engine was running a little hot ~220), so I pulled over to let it cool down some. My transmission got up to 225 degrees and sat idling for a bit until it got to around 205 before trying to head back home. At this point the transmission feels like it’s loading up (feels like brakes are being applied). I switch to manual 1-3 and the loading up feeling goes away but the trans temp starts climbing which got to about 225 right before I got back home.

I picked up the transmission used and recently rebuilt it(I’m an A&P and pretty mechanically inclined). I was very careful and double checked everything (measurements, inspections, etc). I have a ATD pressure gauge hooked up and I have 75 psi idling, around 125-150 cruising, and blipping the throttle it goes up past 200. So I know I have good pump pressure.

I have HP Tuners and it’s not throwing any codes. After cooling off I took the car for a spin yesterday just around the block to see if the issue would rear it’s head immediately but it did not. I have a feeling this issue would arise again if I drove further again.

I have a feeling that my older OEM TQ might be slipping causing the heat to build up rapidly? Would a slipping TQ converter be apparent right away or would the issue arise after the trans gets up to temp and then start slipping?

Could be on the wrong path entirely?

Also the trans did the exact same thing prior to rebuilding it and when it was binding up the first time I pushed it throttle wide and I ended up losing 3/4. So I didn’t want to repeat this again after just rebuilding it.

Thanks in advance!

 

What happens when you command TCC on and off with HPT?

 

Stock 4l60E converters are notoriously known for failing and putting metal throughout the trans, Sad thing is that it got worse when GM built the 6l80e.

 

I can hear the solenoid click when I command it in HTP. I haven’t tried commanding the TCC while driving yet though.

 

See what happens. Id say converter is shot

 

The 4L Family Transmissions are NO WHERE near as bad as the 6L Family as far as Stock Torque-Converters...

The 6L Units are FAAAAAARRRR WORSE!!!
LMAO!


The 8L Transmissions and Torque-Converters are BOTH crap!

And NOW the 10L Transmissions/ Electronics are looking rather questionable...

 

I just finished taking the car for a spin to test the TCC solenoid by command. I tried a few times Cruising about 50 mph and then on the highway about 65 mph and when commanded it engaged and worked. I could feel the rpm’s drop down a tad and it felt like a gear change into OD. The transmission temp hovered around 170 and held about 180 for a few mins.

Then around 20 mins of driving ~15 miles the trans temp shot up from 180 to 215-220 and I could feel the car start to load up. Once I got the car back into my garage I took three temp reads, the transmission cooler was at 235, the pan was at 140, and the torque converter was at 230 ish as well. I did have to command TCC unlock a couple times earlier in the drive because coming to a stop I could feel it bogging down.

Do I have a cooler line blockage issue? It seems odd that the transmission pan was reading what seems to be a normal temp, but yet the cooler and TQ converter were both really hot.

I do have a new TQ converter showing up tomorrow so I have my fingers crossed that will fix this.

I really appreciate your guy’s help on this.

 

I attached the HPT Log file to help if needed. (I tried to edit and attach it to my previous post but kept getting an error)

 

What part of "sad thing is that it got worse when GM built the 6l80e" Didn't you understand? My post stated that the 6l80e was worse... Did I need to specifically say way worse to appease you or something?
Yes they are worse but many still last a long time, I just pulled one that lasted 257,000 miles and the 4l60e before that only lasted 227,000 and the one before that had less than 150,000 before it started to fail.

BTW they do sell an updated converter and a kit for the trans that are supposed to fix the issue on the 6l80e, I guess time will tell.

 

Well I replaced the TQ converter and the problem still persists. I have good pump pressure and I took IR readings on the cooler, pan, and torque converter. The cooler and TQ converter were hot @245 degrees. Trying to narrow down my troubleshooting suspect areas leaves me with possible oil cooler and/or line blockage possibly?

Am I missing anything that could cause this overheating issue? Something internal that was missed that would cause this? It’s weird that after changing all the seals, bushings, etc. that the same issue is happening.

any input is greatly appreciated.

 

Pull the trans cooler return line from the transmission, start engine and check fluid flow.

 

This sounds like a cooler flow issue. Converter is your only real heat source. Without a converter your transmission will heat up, but very slowly. Think about marine units that use a coupling instead of a converter. some don't even have a cooler.
Loop your cooler lines or install a trans cooler. Monitor your trans temp & go for the same drive to your parents house. see how hot it gets at the same mile marker.

 

Well I put a new TQ converter in and a new larger trans cooler with electric fan. I also bought a upgraded VB with the Sonnax TCC sleeve and regulator, and Sonnax AFL valve. I installed a new pump with Sonnax TCC apply valve and boost valve.

I’m still running into the same issue. The trans temp seems to rise normally and once I get to around 180 degrees is when this issue arises. It feels like a clutch pack is still engaging/dragging somewhere and driving while it is doing this is causing the trans temp to quickly rise to over 230 ish degrees.

The car shifts perfect until it gets to that hotter temp. I feel like I am missing something really small that is rearing it’s head when the temp rises and the fluid is thinner and can make its way to somewhere it’s not supposed to be. I’m just about at the point to make a phone call and just buy a new transmission.

 

Any DTC's?

 

I have a P0101 for Mass or volume airflow A circuit range. (Pending/old)

I also maxed out the misfire tables just incase that might negatively impact the transmission.

 

I also wanted to add that once I started to feel the binding up and temps start to skyrocket that the trans wouldn’t have TC lockup.

 

Im not sure why you are trying to diag a trans issue when you clearly have engine performance issues which will effect trans function and or health of it.

 

I briefly had that code and rectified it. 9/10 times I’ve driven this car it hasn’t had any DTC’s. It’s definitely an internal issue of some sort to the transmission.

I just took the car out for a drive and once it got up to temp and I started to feel it bind up I returned to the house and disconnected the main plug to see if it was an electrical issue and it didn’t change anything, still binding up. I’m not sure if this matters but the bind up affects both forward and reverse.

Trying to troubleshoot this down the area/items I suspect could possibly be the culprit are

• Forward sprag (Possibly slipping when hot?)
• Input shaft to drum (Did WAT at tear down with no visible bubbles, maybe with high temps it leaks?)
• Leak in the forward clutch piston housing(even though the forward clutch molded pistons are new, old housing)

The one common denominator is that this issue only happens when hot, and the fluid is able to sneak through areas that it can’t when cold.

This is a frustrating issue to say the least.

I really appreciate your guy’s help.

 

The forward sprag and Input shaft to drum will not cause binding when hot. If the 3-4s apply with the forward clutches that could cause the binding.

 

if the 3/4's apply with the forward clutches...you'll just have 3rd gear
wouldn't bind

If you're in 1st but the band applies...that's just 2nd

if you're in 2nd with the band applied and the 3/4's happen to come on (they won't because of exhaust paths through the valve body...but for sake of conversation let's entertain it)
then you'll just have 4th

if you're in 3rd and the band comes on...just 4th

the only real bind possible is to have the reverse input clutches come on in a fwd range

or possibly the low/rev clutches in a gear other than 1st