Exhaust System - Diagnosis & Repair Procedure

88subaru08

NUMBER 09-25-88

DATE 12-27-88

1985 AND 1986 L AND XT SERIES NON-TURBO VEHICLES

SUBJECT: EXHAUST Y PIPE IDENTIFICATION, NOISE DIAGNOSIS AND REBUILD PROCEDURE

FIGURE A - Y PIPE MODEL YEAR IDENTIFICATION:

IDENTIFICATION

This rebuild procedure has application for 1985 and 1986 non-turbo vehicles utilizing the OEM double wall Y pipe. Use the following information to assist you in identifying different year Y pipes.

If the Y pipe has a weld-on cover shield, it's either a 1985 or 1986 pipe. If the pipe has a bolt-on cover shield, it could still be a 1985 or 1986. With the catalytic cover shield removed, the indentation on the catalytic converter can be used to provide positive indentification. 1985 and 1986 Y pipes had a narrow, shallow groove located on the upper and lower halves of the converter. 1987 and 1988 Y pipes use a slightly deeper, wider indentation with more squared off sides and flat bottom. (See Figure A)

FIGURE B - SINGLE WALL Y PIPE IDENTIFICATION:

The difference between double wall and single wall Y pipes is that the single wall Y pipe incorporates shielding on the connecting pipes as well as the catalytic converter itself. Single wall Y pipes were incorporated in production in mid 1988. (See Figure B)

NOISE DIAGNOSIS

Double wall exhaust components can be difficult to diagnose for noise or rattling conditions because of the tendency to resonate to other double wall components. Noisy Y pipes can be confirmed for this condition by disconnecting the Y pipe from the vehicle, supporting the pipe by its rear flange and allowing it to hang free and tapping along its length with a rubber mallet. The noisy or cracked area can be identified by the change in pitch when the mallet passes over the affected area.

REBUILD OVERVIEW

Component parts are now available that will allow for the rebuilding of the Y pipe assembly. The rebuild procedure involves cutting the three pipes off of the catalytic converter, inserting three replacement pipes, and welding the pipes to the catalytic converter after ensuring proper alignment. IT IS NOT NECESSARY TO REMOVE THE OXYGEN SENSOR DURING THIS PROCEDURE. TAKE CARE NOT TO DAMAGE THE OXYGEN SENSOR. Welding is required with this procedure. A MIG type welder is recommended. NEVER ATTEMPT TO GAS WELD OR BRAZE A CATALYTIC CONVERTER OR THE PIPES. The Y pipe and converter shell material will vary according to date of manufacture. Stainless steel (AISI 409) 1.2-1.5 mm thick as well as high strength aluminized steel have been used for both the pipes and cover.

TOOL REQUIREMENTS

- MIG welder and related safety equipment
- Vise grip type pliers - wire brush
- Hand tools - sockets and wrenches 10 mm through 14 mm
- Hacksaw and spare quality replacement blades

REBUILD PROCEDURE

Step 1 After the Y pipe has been removed from the vehicle, remove the
catalytic cover shield. Bolt-On covers can be unbolted while the welds on the weld-on cover can be broken by gripping with the vise grip pliers and bending back and forth until broken. The weld-on cover will not be re-used, however, bolt-on covers should be re-used. Do not remove the oxygen sensor. Take care not to damage the sensor during rebuild.

FIGURE C - CUT LOCATIONS:

Step 2 Clamp the Y pipe assembly in a vise and use a hacksaw to cut
off the three pipes. An acetylene torch must not be used for this operation. The cut should be just inside the factory weld and at a 90 degree angle from the pipe. (See Figure C)

Step 3 Remove the remaining pipe ring section which will remain just
inside the catalytic converter after sawing the pipes off. Remove any metal shavings that my have fallen into the catalytic converter. Use care around the sharp edges.

Step 4 Check the appearance of the converter honeycomb to assure that
it's not broken, plugged, or otherwise physically damaged. Should the converter be damaged, the Y pipe cannot be rebuilt and must be replaced.

Step 5 Insert the replacement pipes into the converter housing and
check for a snug fit. If the replacement pipes fit poorly in the converter housing, carefully bend the surrounding catalytic shell material to close the gap. Wire brush the area on the converter housing to be welded to ensure continuity when welding.

FIGURE D - EXHAUST SYSTEM TO BODY CLEARANCE SPECIFICATIONS:

Step 6 Reinstall the loosely assembled Y pipe on the vehicle. Use
gaskets and tighten securely. With the vehicle now acting as a holding jig, position the replacement pipes and converter so the clearances meet with the specification listed in Figure D. Tack weld the pipes into position (2 tacks per pipe are recommended). Number 308, 309 or equivalent welding wire can be used for this welding operation.

CAUTION: ATTACH WELDER GROUND CLAMP TO EXHAUST SYSTEM TO PREVENT DAMAGE TO VEHICLE ELECTRICAL SYSTEM.

Step 7 After tack welding, remove the Y pipe from the vehicle and weld
the entire 360 degrees around the replacement pipes.

Step 8 Allow the pipe to cool and reinstall the bolt-on catalytic
converter cover shield. If the pipe you are servicing had a welded cover initially, install a new bolt-on cover shield. Make certain the new welded area does not interfere with the fit of the cover shield.

Step 9 Reinstall the Y pipe on the vehicle and check for alignment and
exhaust leaks.

PARTS INFORMATION

Y Pipe Rebuild Kit

All applicable models - includes three replacement pipes and one rear doughnut type gasket . . . . . . . . . . . . . .P/N 44105GA310

Cover Shield

All Calif. Carb., Federal carb. and 4WD Calif. Carb. vehicles. . . . . . . . . . .P/N X4401GA100 All MPI and SPI Non-Turbo vehicles . . . . . . . .P/N X4401GA110 All Federal 4WD Non-Turbo vehicles . . . . . . . .P/N X4401GA120

WARRANTY INFORMATION

Operation # Failure Code Time

A436-311 HCR-01, 22, 25, 42 1.5 Hr.