I did a 4L80E swap on my Truck. I installed a brand new Pro Series Circle D 1B 258mm. I also bent up stainless lines out to a front mounted Tru-Kool 40K. I also installed the Derale deep pan with cooling tubes (+4qt capacity). I'm using AC-Delco Dex VI fluid.

I'm running about 13psi boost so nothing crazy. The transmission did fine, temperature-wise, all fall/winter but now as spring comes in with 60+ degree days, the temp climbs quickly in traffic. Its getting north of 200 degrees which according to what I've read is no good for transmissions long term. By the time I get home to my driveway temps have crept up to 220 or more. If I'm able to sustain 40-50mph with light throttle, it cools down a bit, but in traffic thats not always an option.

FWIW, I had a used 4L80E for a short period of time and the temp did the same exact thing. Circle D tells me this converter is not considered "loose" by any means but to me it feels very loose. If you get on the pedal hard, its like a sling shot, but under light throttle...not so much. I sent the first one back to Circle D to be cut and cleaned and they found no issue inside so I'm at a loss as to why I'm getting so much heat.

 

What lines did you use? What fittings in the trans are you using?

 

I fab'd the lines from a roll of 3/8 stainless and left the stock trans fittings in place with a 3" stub from the stock lines and did a flare union to connect my part.

 

Is the converter locking?

 

Lines are crimped or anything are they? I might pull a line off and check to make sure you are getting fluid flow.

 

The converter does lock, yes. When it locks, the temps drop quite a bit, but then again I'm doing 48MPH at that point so air is moving trough the tru-kool and all is well. On a long trip, it will drop to around 120 no problem.

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No crimps in lines. I can definitely pull a line and see how well it flows again. I ran a can of Kooler Klean through and it came right out the other end. Also ran compressed air at about 100 psi through and it blew out great. I don't think its a restriction.

Am just curious, does a high stall converter generate heat by design (slipping) and so I should expect these high temps when doing alot of stop and go? or... am I justified in my concern here?

 

Something is definitely wrong. Stop and go houston traffic in 100F temps my trans never goes over 145

 

Ya, my 80e consistently runs 50 above ambient temp.

 

transbuilderguy (Robert Godfrey) has a post on his FB about an 80e where someone used the wrong rear fitting,causing a heat issue and roasting the trans.

The issue was that they had used an AN type fitting instead of the stock, long snout fitting. This caused fluid to not circulate properly and overheated the transmission.

I would also feel the lines. With temps that high I would think one would be cold to the touch and the other scorching hot.

 

Thanks for the sanity check guys... Having gone through most of the physical stuff a number of times (including burning up one 80e already in the process) I am starting to suspect something in the tune. I had to scale my entire tune for 88lb injectors because the E38 ECM can only go up to 63.5 lb/hr. As a result my delivered Torque PID was reporting all screwed up. I ended up scaling all the trans table axis which made it much much better but I suspect there is more to be done for the low end driving range. perhaps the Torque coefficient EQ Ratio? donno.

I guess I just need to figure out how and what to log to determine if I'm slipping more than I should be before I burn up another trans.