RTV SILICONE SEALANT USAGE THM 125-C ,200-C AND 200-4R

SOME THM 125-C, 200-C AND 200-4R TRANSMISSIONS ARE NOW BUILT WITH RTV SILI- CONE SEALANT ON THE OIL PAN AND THE CONTROL VALVE OIL COVER IN PLACE OF A CORK GASKET. IN CONJUCTION WITH THIS CHANGE THE FLANGE ON BOTH THE OIL PAN AND THE CONTROL VALVE OIL COVER HAS BEEN REDESIGNED TO ELIMINATE THE RAISED STIFFENING RIB (REFER TO FIGURE 1), MAKING THE FLANGE FACE FLAT (REFER TO FIGURE 2).

THIS BULLETIN OUTLINES THE SEALING METHODS AND SERVICE PROCEDURES ASSOCIATED WITH THE VARIOUS OIL PAN AND OIL COVER FLANGE CONFIGURATIONS.

SEALING METHODS

GASKETS MUST BE USED ON ALL OIL PANS WITH RAISED STIFFENING RIBS ON TH FLANGE (REFER TO FIGURE 1).

GASKETS MUST BE USED ON ALL THM 125-C CONTROL VALVE OIL COVERS WITH RAISED AND DEPRESSED STIFFENING RIBS ON THE FLANGE (REFER TO FIGURE 1 AND 2).

2. RTV SILICONE SEALANT MUST BE USED ON ALL OIL PANS AND THM 125-C COROL VALVE OIL COVERS THAT HAVE A FLAT FLANGE (REFER TO FIGURE 2).

IF RTV IS USED ON AN OIL PAN WHICH HAS DEPRESSED RIBS, THE BEAD OF RTV RTV MUST BE PUT ON THE HIGH PORTION OF THE FLANGE FACE, NOT IN THE GROOVE (REFER TO FIGURE 2).

3. EITHER GASKETS OR RTV SILICONE SEALANT SHOULD BE USED ON OIL PANS THAT HAVE DEPRESSED STIFFENING RIBS ON THE FLANGE (REFER TO FIGURE 2).

IF RTV IS USED ON AN OIL PAN WHICH HAS DEPRESSED RIBS, THE BEAD OF RTV MUST BE PUT ON THE HIGH PORTION OF THE FLANGE FACE, NOT IN THE GROOVE (REFER TO FIGURE 2).

IF A CORK GASKET IS USED ON A RIBBED OIL PAN, WHICH WAS PREVIOUSLY ASSEM- BLED WITH RTV, ALL RTV MUST BE REMOVED FROM THE OIL PAN AND CASE FLANGE BEFORE REINSTALLATION.

SERVICE PROCEDURES

1. TO REMOVE THE THM 200-C OR 200-4R OIL PAN ASSEMBLED WITH RTV, USE THE NORMAL SERVICE PROCEDURE. IF THE OIL PAN DOES NOT COME FREE WHEN ALL THE ATTACHING BOLTS ARE LOOSE, TAP THE OIL WITH A RUBBER MALLET. DO NOT PRY BETWEEN THE PAN AND CASE FLANGES.

2. TO REMOVE THE THM 125-C OIL PAN ASSEMBLED WITH RTV SEALANT, FOLLOW THIS PROCEDURE:

A. A SPECIAL BOLT WILL BE REQUIRED TO REMOVE ANY THM OIL PAN ASSEMBLED WITH RTV SEALANT. THIS SPECIAL BOLT CAN BE MADE FROM AN OIL PAN BOLT BY GRINDING DOWN A SECTION OF THE SHANK DIAMETER, JUST BELOW THE BOLT HEAD, TO APPROXIMATELY 3/16" (REFER TO FIGURE 3).

B. REMOVE ALL THE OIL PAN BOLTS EXCEPT THE TWO SHOWN IN FIGURE 4. THEN REMOVE BOLT "A" (REFER TO FIGURE 4) AND INSTALL THE SPECIAL BOLT, FINGER TIGHT, IN ITS PLACE. NOW LOOSEN BOLT "B" FOUR COMPLETE TURNS.

DO NOT TRY TO PRY THE OIL PAN LOOSE FROM THE CASE AS DAMAGE TO THE PAN FLANGE OR CASE WILL OCCUR.

C. WITH A RUBBER MALLET, STRIKE THE OIL PAN CORNER INDICATED IN FIGURE 4.

D. REMOVE THE SPECIAL BOTL AND ALLOW THE FLUID TO DRAIN.

3. TO REMOVE THE THM 125-C CONTROL VALVE OIL COVER, FOLLOW THIS PROCEDURE:

A. REMOVE ALL OF THE RETAINING BOLTS, EXCEPT TWO. THE TWO REMAINING BOLTS SHOULD BE 180 DEG. APART AND ONLY FINGER-TIGHT.

DO NOT TRY TO PRY THE OIL PAN LOOSE FROM THE CASE AS DAMAGE TO THE PAN FLANGE OR CASE WILL OCCUR.

B. WITH A RUBBER MALLET, STRIKE THE EDGE OF THE OIL PAN TO SHEAR THE RTV SEAL.

C. REMOVE THE TWO REMAINING BOLTS AND ALLOW THE FLUID TO DRAIN.

4. TO INSTALL ANY OIL PAN WITH RTV SEALANT -

A. IF PREVIOUSLY ASSEMBLED WITH RTV, USE A SHARP EDGED PLASTIC SCRAPER TO REMOVE ANY EXCESS OR LOOSE RTV SEALANT REMAINING ON THE OIL PAN OR CASE FLANGE. REMOVE ANY LOOSE RTV WHICH MAY HAVE FALLEN INTO THE CASE OR OIL PAN. THE FLANGES DO NOT HAVE TO BE COMPLETELY CLEAN, ONLY THE LOOSE OR EXCESS RTV MUST BE REMOVED.

B. USE A CLEAN, DRY RAG AND SOLVENT TO DRY THE CASE AND OIL PAN FLANGES.

NOTICE: IF THE CASE AND OIL PAN FLANGES ARE NOT DRY AND FREE OF ANY OIL FILM, LEAKAGE MAY RESULT.

C. INSTALL A 1/16" BEAD OF RTV SEALANT ON THE OIL PAN FLANGE AND INSTALL WHILE THE SEALANT IS WET. THE BEAD OF RTV MUST BE APPLIED AROUND THE INSIDE OF ANY BOLT HOLES (REFER TO FIGURE 2).

D. INSTALL OIL PAN BOLTS AND TORQUE TO PROPER SPECIFICATIONS.

5. THE RTV SEALANT CURRENTLY RECOMMENDED FOR TRANSMISSION SERVICE APPLICA- TIONS CAN BE ORDERED FROM GMWDD IN A THREE OUNCE TUBE, PART NO. 1052366, OR A TEN OUNCE TUBE, PART NO. 1052434.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.