Thump At Cold Start (00-059)

THUMP AT COLD START

TECHNICAL SERVICE BULLETIN

SYMPTOM

A thump as the ignition switch is released from the start position or as the engine starts. This noise sounds similar to a rubber mallet striking the frame and occurs only on a cold start (the vehicle has been sitting for some time, usually overnight).

PROBABLE CAUSE

The vacuum-actuated engine mount does not work properly because of insufficient intake manifold vacuum at start-up.

CORRECTIVE ACTION

To increase vacuum, reroute the vacuum hose for the engine mount control solenoid valve to the cruise control vacuum tank.

PARTS INFORMATION

WARRANTY CLAIM INFORMATION

In warranty:  The normal warranty applies.

OP#	Description	FRT	Template ID
124105	Repair vehicle using bulk vacuum hose P/N 95001-35001-60M, H/C 6308019 (1998-00 Accord)	0.3	00-059A
124105	Repair vehicle using bulk vacuum hose P/N 95001-35003-60M, H/C 4260329 (1998-00 Accord)	0.3	00-059B
124105	Repair vehicle using bulk vacuum hose P/N 95005-35008-10M, H/C 2325058 (1998-00 Accord)	0.3	00-059C
124107	Reroute engine mount control solenoid valve vacuum hose (2001-02 Accord)	0.3	00-059D

Failed Part: P/N 50810-S84-A82, H/C 5438585

Defect Code: 042

Contention Code: B07

Skill Level: Repair Technician

Out of warranty:  Any repair performed after warranty expiration may be eligible for goodwill consideration by the District Service Manager or your Zone Office. You must request consideration, and get a decision, before starting work.

DIAGNOSIS

Ask your customer if the noise happens only on a cold start, after the vehicle has been sitting for some time, usually overnight.

• If the noise happens only on a cold start, go to REPAIR PROCEDURE A - 1998-00 ACCORD or REPAIR PROCEDURE B - 2001-02 ACCORD.
• If the noise happens at every start, disregard this bulletin, and look for other possible causes (exhaust hangers, rear engine mount, etc.).

REPAIR PROCEDURE A: 1998-00 ACCORD

1. Look at the three vacuum ports on the top of the intake manifold. Is vacuum port C capped? See Fig 1 .
   • If port C is not capped, replace the fuel pressure regulator and hose (see S/B 00-018, MIL COMES ON WITH DTCS P0171 AND/OR P0172 , filed under Fuel and Emissions). Then go to step 2.
   • If port C is capped, go to step 2.
   Fig 1: Vacuum Port C

   
2. Disconnect the three vacuum hoses from the Y-fitting. Save the Y-fitting. See Fig 2 .
   Fig 2: Y-fitting

   
3. Remove the hose from vacuum port A, and discard it.
4. Remove and discard the long vacuum hose going to the fuel pressure regulator. Save the double hose clip.
5. Unclip the cruise control vacuum hose from the intake air duct. Measure 4-1/2 inches from the check valve on the cruise control vacuum tank, then remove a 1/2-inch section of the hose beyond this point with a utility knife. See Fig 3 .
   Fig 3: 1998-00 Cruise Control Vacuum Hose

   
6. Connect the ends of the vacuum hose you just cut to the opposite ends of the Y-fitting you removed in step 2. See Fig 4 .
   Fig 4: Engine Mount Control

   
7. Connect the engine mount control solenoid valve vacuum hose to the open port on the Y-fitting. Push the hose into the clip on the side of the intake air duct.
8. Cut a 34-inch length of 3.5 mm ID vacuum hose, then connect one end to vacuum port A and the other end to the fuel pressure regulator. Push the new hose into the clips at the locations shown. See Fig 5 .
   Fig 5: New Vacuum Hose

   

REPAIR PROCEDURE B: 2001-02 ACCORD

1. Disconnect the engine mount control solenoid valve vacuum hose from vacuum port A. Unclip the hose from the double hose clip and from the side of the intake air duct. Remove and discard the double hose clip. See Fig 6 .
   Fig 6: Disconnecting Vacuum Hose

   
2. Measure 3 inches in from the open end of the hose, and remove that section of hose with a utility knife. See Fig 7 .
   Fig 7: Removing Vacuum Hose Section

   
3. Unclip the cruise control vacuum hose from the top of the intake air duct. Measure 4-1/2 inches from the check valve on the cruise control vacuum tank, then remove a 1/2-inch section of the hose beyond this point with a utility knife. See Fig 8 .
   Fig 8: 2001-02 Cruise Control Vacuum Hose

   
4. Connect the ends of the vacuum hose you just cut to the opposite ends of the new Y-fitting. See Fig 9 .
   Fig 9: Connecting Vacuum Hose

   
5. Connect the engine mount control solenoid valve vacuum hose to the open port on the Y-fitting. Push the hose into the clip on the side of the intake air duct.
6. Push the cruise control vacuum hose into the clip on the top of the intake air duct.
7. Push the new cap onto vacuum port A.