: Pre-'05 4T80E Torque Converter Upgrade from viscous silicone to '05-later EC3?

Manic Mechanic
10-16-12, 01:44 PM
While reasearching and planning my drive-train overhaul I've looked heavily into going into my transmission to make repairs and possibly some updates. I know my TCC lock-up pressure Solenoid is bad. I have also read and reasearched the TSB concerning replacing the seals in the hydraulic pressure circuit that are known to fail and also prevent converter lock-up. I'll put it here:

Subject: Service Engine Soon (SES) Light On, Diagnostic Trouble Code (DTC) P0741, Torque Converter Clutch (TCC) Excessive Slip, Transaxle Chuggle, Slip/Surge (Inspect/Replace Internal Transaxle Components) #04-07-30-034 - (08/06/2004)

Models: •1998-2002 Cadillac Eldorado

•1998-2004 Cadillac Seville

•1999-2004 Cadillac DeVille

•2000-2003 Oldsmobile Aurora

•with 4T80-E Auto Transaxle (RPO MH1)


Some customer may comment on the SES light on and a chuggle or surge. Diagnostics may show excessive TCC slip speed and DTC P0741 will be current code stored.

Seal damage may allow the TCC apply fluid to leak into the channel plate, causing excessive TCC slippage under certain conditions, eventually causing no TCC apply.

TCC may have partial apply fluid pressure or no apply fluid pressure. If excessive slip speed is noted and condition/cause cannot be corrected by using DTC P0741 diagnostic chart, suspect worn seals from slippage of the drive sprocket bearing inner race on the drive sprocket.

DO THIS------------------------ DON'T DO THIS

Repair the transaxle ------------DO NOT replace the complete transaxle assembly

Follow the diagnostic and repair procedure below to repair this condition.

Remove the transaxle from the vehicle. Refer to the appropriate Service Information for transaxle removal procedure.
Remove the torque converter.
Install the transaxle to holding fixture. Refer to Holding Fixture Installation SI Document ID #513730.
Remove the transaxle side cover, upper valve body and case cover. Refer to the appropriate Unit Repair Information in SI.

Inspect the two case cover seals (34 and 35) for uneven wear patterns.

Inspect the two case cover seals (34 and 35) for uneven wear patterns. The wear patterns will be evident by a uneven wear pattern of the inner diameter white seal surface as shown in the two above illustrations.

Inspect the two case cover seals (34 and 35) for splits/tears and or flat spots.

Inspect the support drive socket (400) for wear on the bearing race.
Inspect the case cover (33) for wear or damage due to the drive sprocket bearing spinning in the bore.

•During the tear down inspection, pay particular attention to seals (34, 35, 409 and 412) for wear or damage.

•Seals (34, 35, 409 and 412) are part of Gasket Kit, P/N 24221398, and do not need to be ordered separately.

•Replace the Torque Converter when servicing a vehicle with this condition.

•Flush the transaxle cooler with Transflow cooler flushing tool, J 45096. Refer to Service Bulletins:

•Info - Automatic Transmission Oil Cooler Flush and Flow Test Essential Tool J 45096, TransFlow #02-07-30-052

•Transmission Cooling System Service Tool J 45096 - Transflow Information #03-07-30-002.

Replace only the necessary internal transaxle components per the tear down inspection.
See the parts list below.

My parts list (Thanks to AJxtcman)

Item #----------Description-------------------------Part #
1--------Torque Converter Assembly----------------???????? 3 to choose from
30-------Side Cover To Case Cover Gasket----------8679392
33-------Transmission Case Cover------------------ 24229131
43-------Sprocket Support to Case Cover Gasket----24208779
44-------Case to Case Cover Gasket----------------24208778
228------Pump Body & Spacer Plate Gasket kit------ 24231071
336------TCC Pressure Solenoid-------------------- 24227792
400------Drive Sprocket Support--------------------8681071
412------O-Ring Seal-------------------------------8686052
---------ATF 10 Quarts

AJ's list specs the needed gaskets separately so you don't have to buy a $250 kit.

Since replacing the converter is part of the plan and AJ said once that he's seen several techs try to leave the converter in and it came back I started pricing converters. Since Viscous Silicone style converters have been known to fail and ruin the trans, esp. when it's a reman as documented here by maeng9981

I tried to see if there is a better option such as a performance built unit. I noted several companys either recommending or stating that the older spring hub clutch type lock-up converters like in the first years Alante could be used for less expensive and more durable repair with the only change being a much more notable engaugement (like another gear) which some customers object to. I don't think that it would bother me as it already has 4 gear changes. While searching for more tech info on the swap I found this interesting article from 2005 a few times on a few sites that explains and documents how to instead change the converter up to the later model Electronically Controlled Converter Clutch like on the DTS and newer N* cars. The main reason is smooth engagement with a more durable converter compared to the sprung hub and viscous silicone:
WARNING: It's alot of PDF and takes a while to download. Try opening on a separate page and coming back to it in a few.


So I reasearched it. Turns out all the parts are still availible as a relativly inexpensive kit, they may be standard issue for new units also but the kit supposidly works perfectly to update the 4T80E for EC3 operation. The only hitch in my get-along is the PCM software update mentioned. I can't find anything about it anywhere. I've searched the net, my subscription auto repair information sites that list such things, I've looked at GM's calibration updates availible for my 2001, I went and talked to my local Cadillac service advisor and his Caddy Tech and niether of them had ever heard of it but they usually just install new by the book parts anyways, I went to what is one of the best transmission rebuilders in town (Conroe, TX pop. approx. 100K-200K) and while he was very familar with installing the old hub lock-up units without any programming needs or resulting codes he knew nothing about the EC3 swap or any flash updates to support it. So now I'm at the point that I'm asking you guys, AJ in particular since he would be the most likely to know, if any of you have heard of this swap, done it, or know enough about it to say what happened to the programming? I'm thinking that, A. they never released it or have since pulled it due to problems or lack of use etc., or B. it turned out to be unwaranted because like swapping the older hub units in the EC3 caused no problems with current programming and CEL's so it was dropped, or C. it's there I just don't know where to find it and one of you guys can tell me.

Does anybody know or can find out about this?
Thanks for you consideration and reading this far.

Manic Mechanic
10-21-12, 07:15 PM
So nobody knows. I'm not sure what I will do. I started thinking (convincing myself) that if the old style clutch converters can be used without setting codes then why couldn't the newer style that acts more like the silicone style? The EC3 conversion even has hard parts to match. I PMed AJ, and I see that he is active on the forum often but no posts from him of late.


10-22-12, 03:52 AM

Here's an interesting pdf I found while looking for some similar thoughts...apparently it can be done but needs parts replacement more than the torque converter itself, and possibly a PCM reflash.