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'97 STS Transmission servo cover


KHE

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I got home from work Friday night and saw a puddle below my '97 STS so I began to investigate. It was trans. fluid and I initially thought the pan gasket was leaking (I changed the fluid a few weeks earlier). I checked the torque of the pan bolts and all were the proper torque. That's when I saw the source of the leak - it is the area circled in red in the attached scan. I was at the dealer today picking up a trans. pan gasket for my '96 and asked them about the cover. The dealer said it is the 4th gear servo but I cannot locate it in the service manual - I need to know the torque value of the cover bolts. The dealer also said the cover o-ring was all that was probably wrong (my initial guess) and will have the part tomorrow. Does anyone know the torque value of the 4th gear servo bolts? I can't find it in my manual ANYWHERE.

post-45-1160414909_thumb.jpg

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Thanks Jim! It may be a moot point as there is only about 1-1/4" between the cover and the frame - I may not be able to get in there with a torque wrench... I'll have to use the "Mechanic's Feel" :lol: I'm assuming the torque isn't that critical since there is such a wide range in the specification.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I've got a transmission overhaul manual for 1997 but it will be a couple of days before I can get it and have time to drill down to something that specific. I'll track this thread and will do it if I see a need Wednesday night.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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I changed the seal last night. It wasn't that bad of a job but it was messy and keeping the large spring compressed in order to start the bolts was sort of a pain. About 2-1/2 quarts of trans fluid leaked out and it never stopped dripping. The old seal looked OK although it had some compression set to it. I wish I would have bought the piston seal as well but I didn't want to leave the car apart for another two days while the dealer ordered it. The bolt torque is not critical as the housing bottoms out on the case. I was able to get the torque wrench in there though and torqued the bolts to the midpoint of the range JimD provided.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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After the seal replacement on Tuesday night, all seemed OK on a test drive and the drive into work Wednesday was fine. When I was driving home Wednesday night, the trans began to delay shifting into 4th gear for about 5 seconds and then it would shift firmly into 4th. This morning, no 4th gear.... I initially suspected a shift solenoid problem and checked for trouble codes and none were stored. I'm going to pull the servo cover and piston tonight - maybe I had something misassembled? I just can't get past the timing of the problem - 20 miles after I replaced the seal, I started having trouble with 4th gear......

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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You mentioned the piston seal the other day!!

If you could use an exploded view of that assembly, there is a good one in my manual.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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If you could post it, that would be great. My factory shop manual is very incomplete as far as the transmission section goes... I have the exploded diagram from the dealer but I'm sure the one from your manual is much better.

I'm going to pull it apart again tonight - hopefully, I'll find something simple. I doubt it is the piston seal but I'll replace it anyway. I have noticed ever since getting this car driveable 5500 miles ago (Timesert job in May), the trans has a ever so slight pause on the 2-3 and 3-4 shifts - hardly noticable but a momentary pause can be heard and seen on the tach - maybe it is related? Who knows?

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Kevin, my manual states:

NO FOURTH GEAR:

cause:

Fourth Servo Pin broken, seized

Fourth Servo Piston, damaged

Fourth Servo Seals, rolled, cut or damaged

Fourth Servo Cover, Cracked

Maybe the seal was damaged trying to keep that spring in while you put the cover bolts in...? That they say the seal rolled makes me think its a rubber seal and not a metallic seal as they sometimes use.. With not a lot of room it must have been hard to hold it in and get the bolts in

Good Luck, Mike

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Thanks. I recall that section in the book. I'll know more tonight when I pull it back apart. If nothing is obvious, I'll disassemble the piston head from the rod and check to see if the pin moves freely in the bore. Hopefully, it is something simple... :unsure:

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Does anyone else have the transmission overhaul manual for the 4T80-E?

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Does anyone else have the transmission overhaul manual for the 4T80-E?

I am buying one today from ATRA:

http://www.atraonline.com/source/Orders/in...EARCH_TYPE=FIND

Or from ATSG (maybe in a download)

http://www.atsg.biz/cgi-bin/shopper.cgi?pr...%26pricecode%3D

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Legend:

524 = Cover, 4th Servo

525 = Seal, Servo cover

527 = Pin, 4th Servo

529 = Piston, 4th Servo

531 = Ring, Snap

532 = Seal, 4th Servo Piston

533 = Spring and Retainer Assembly

534 = Bolt, (23, 10mm)

http://i70.photobucket.com/albums/i101/Jim...-Eexploded1.jpg

IPB Image

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Happy to assist. I have your email address and if your mail server would not gag on a 900 Kb file, I can send you a full size bitmap image.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Happy to assist. I have your email address and if your mail server would not gag on a 900 Kb file, I can send you a full size bitmap image.

900kb should be OK - I was able to print out the file full size though.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Here is some more info Kevin.

Fourth Servo Overhaul

1) Remove the following parts:

The 4th servo piston seals (532, 525)

The snap ring (531)

The apply pin (527)

The spring and retainer assembly (533)

2) Inspect the following parts:

The 4th servo piston (529) for cracks

The apply pin (527) for damage

The spring and retainer assembly (533) for damage

The servo cover (524) for damage

3) Install the following parts:

The new piston seal (532) onto the 4th servo piston (529)

The apply pin (527)

The spring retainer (533) into the 4th servo piston (529)

Attach the snap ring (531) to the apply pin (527).

4) Install the 4th servo piston assembly (529) and the spring (533) into the 4th servo cover (524). Apply pipe thread sealant GM P/N 12346004 to bolt threads before installation.

5) Install the 4th servo piston and cover assembly into the case

6) Install the 4th servo cover bolts into the case. Hand tighten the bolts while holding the piston compressed. Tighten

Tighten the bolts in a star pattern to 8-14 N·m (6-10 lb ft).

See Photos

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I removed the servo cover Friday night after work and immediately found the problem - the piston seal was damaged - the lip of the seal was torn away from the retaining flange for about half of the circumference. It fell into the drain pan... I must have damaged when replacing the cover seal earlier in the week. I picked up a new seal from dealer at noon Friday so I had it on hand. My next door neighbors stopped by for drinks so I had to leave it until this morning.

I lost a gallon of trans. fluid - that coupled with the 2-1/2 quarts earlier in the week plus the fluid drain and refill in mid August should have resulted in a near 100% fluid exchange. :lol:

Mike, thanks for the diagrams - what page are they on??? My 1996 manual doesn't have those diagrams or procedures and I looked at every page in the transmission section....

Anyway, I reassembled it and took extra care when installing the cover and then tilted the cover so I could see the piston seal and then rotated the piston in order to inspect the entire seal for damage. After verifying there was no damage to the new seal, I bolted up the cover, topped off the trans. fluid and took it for a drive. 4th gear was operational and the 3-4 shifts are once again smooth.

I'd have hated to have to hear a transmission shop say, "Well, we won't know anything until we remove the trans. and open it up..." and "we recommend a rebuild for the tune of $3000".......

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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