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Need some help with 4l80e

Abusfullofnuns

Abusfullofnuns

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hi guys...sorry for the super long first post


I recently purchased a 6.0 liter swapped burb. It's got a 4l80e transmission and np208 with 4.56 gears and elockers. 14sf and 10 bolt front. I've been catching up on a lot of builds and learning about square's thanks to ck5.

Here's my issue...transmission ran great for 1500 miles of street use. It never climbed above 180 degrees. I did experience a slight climb in temps when in 4hi climbing a ski hill. This was about 300 miles into the 1500 mile total to his point. 55k miles on motor and trans.

All was fine until I did a bit of wheeling and had the Trans heat up a few times. I'd say it got to the 220-230 range a couple of times but was cooled down each time it crept up. I chalked it up to low air flow through the cooler as there is no fan and its not mounted in a good location. I think the cooler is around 15x8 with an extra in line filter.

Last week we got some snow and ice and I had to engage 4wd a couple of times. Well I disengaged the hubs, but forgot to shift out of h4 before I hit the interstate. I looked down and the trans temp was 240. I also got a code of p0984 TCC slipping.

I cleared the code and did some local driving and the trans barely heated to operating temp. Seemed to be a non issue until I got on the highway. After 15 minutes of higher speeds the trans starts to heat up and never stopped climbing. Shift to neutral and it cools down a bit but jumps up as soon a drive is engaged.

I ordered two 7 inch fans to take care of the airflow issue and decided to change the fluid and filter last night ahead of the fan delivery. The fluid didn't look great but the pan was clean other than the magnet. I'm not knowledgeable enough to say whether the amount of material on the magnet was good or bad.

Unfortunately the fluid refresh did not cure the problem. The max temp it reaches has lowered 210-220ish and it takes longer to heat up but the problem is still there. Anything more than 10 miles of interstate driving and it starts to heat up and the TCC code reappears after 30 minutes or so.

I assume that there is a lock up problem with the torque converter but tranny's are not my strong suit.

I guess I am looking for confirmation that it's likely a faulty torque converter and not just the TCC solenoid. I have not checked line pressures, but it engages each gear fine and the shifts are solid.

Is there anything else I can check to cover my bases? I only have a Bluetooth adapter with torque app, and no real access to a real scanner.
 
Thank you. I know this may be a shot in the dark at solving without a good scan gauge. I find it hard to believe that the tranny is bad though. It shifts great and will power brake the 35" mtr's with out issue. It's not a habit, but tested it out last night after the fluid refill.
 
Sounds like you may have a broken lockup piston in your converter, this is quite common and will require a torque converter rebuild or replacement.
 
Greg Ducato said:
Sounds like you may have a broken lockup piston in your converter, this is quite common and will require a torque converter rebuild or replacement.
Click to expand...
Thanks a bunch for the response. Any way to diagnose that further without pulling it? Will I know for sure when I put my hands on the TC?

I'll go ahead and get a TC on the way and knock it out this weekend. I don't know much about TC's but assume for a street/rocks truck that I want a low stall version. Anyone have any tips on where to look for a good one for this application?
 
Hugh's Performance makes a nice 4L80E torque converter for towing. They are expensive though. They also make an SFI rated flexplate that are specifically designed for the 4L80E torque converter...also expensive.
 
Greg Ducato said:
Sounds like you may have a broken lockup piston in your converter, this is quite common and will require a torque converter rebuild or replacement.
Click to expand...

That is why I got a billit steel piston for my 4L80E torque converter because it is such a common problem.
 
It looks like the problem with a Hughes is the lead time. I'm not excited about the price but I haven't found one that will ship before the 20th. I'd really like to get this thing done this weekend.
 
The factory 6.0 4L80E converter is a high stall, you can choose a lower stall from a good supplier. Any quality rebuilder will have replaced or modified the piston. PM me if you cant find what you are looking for.
 
It looks like the only two that I can get here by this weekend is a B&M traveler with a 2k stall or a daaco(somewhat local).

I'm going to make a few calls before pulling the trigger on the B&M unless someone has good experience with daaco. I've never heard of them but always used pro torque in my go fast cars.
 
at this time frame point I say keep it simple stupid .

new stocker or reman . . . fancy later if you need it .
 
sweetk30 said:
at this time frame point I say keep it simple stupid .

new stocker or reman . . . fancy later if you need it .
Click to expand...
Probably sage advice, thanks. I plan to add an Eco Box or other doubler, so this won't be the last time that I'm pulling the transfer case/transmission.
 
The reason Hughes Performance 4L80E converters are so expensive is that they have a lock-up clutch design that is way beefier than the stock one. I had my 4L80E torque converter rebuilt by a local guy who installed a billet piston, billet stator, and new clutch material for about $275. I supplied the piston and stator from Sonnax for about $150. I have seen reman 4L80E converters with billet pistons on Ebay for a decent price. Cannot tell you the quality of the converters though.
 
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Thanks for the replys. I have a heavy duty version from dacco on the way. They didn't have one with the billet piston built but had one with a billet cover. I talked with them for a while about whether to wait and they recommended to just get this one coming.
 
Well.....converter didn't fix it. The code has popped a couple of times on the interstate this week. When it does, the temp build up a bit. Trans runs at 150-160 otherwise.

I guess I'll replace the TCC solenoid and valve before tearing it back out again. if the problem still exists afterward, I guess I'll try rebuilding the pump??

Everything with the trans feels great other than this issue. Line pressure goes up when the fault is registered.

Am I on the right track?

@Greg Ducato ???
Thanks for the help everyone.
 
Greg Ducato said:
There are also engine codes that can keep a converter from locking such as Random Misfire and some MAF codes as well. Be sure the rest of the house is in order before you start replacing parts
Click to expand...

Thanks. Am I wrong to assume that those issues would trigger my check engine light or be stored in the computer? I haven't gotten any other codes, and all the emission systems are ready except secondary o2s are non existent.
 
how are 2nd o2 parts removed ?

if not set in computer correctly like a hack/slash tune they could have screwed up the programing .
 
sweetk30 said:
how are 2nd o2 parts removed ?

if not set in computer correctly like a hack/slash tune they could have screwed up the programing .
Click to expand...

The computer was flashed and harness supplied by speartech with some additional tuning by lt1swap.com.
 
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