Protegé FAQ - TSB B005/96

B005/96 ENGINE NOISE DUE TO CARBON ACCUMULATION

Note: This bulletin supersedes the following TSB(s): B004/93. Please update your records accordingly.

APPLICABLE MODELS/VINS

1990 - 96 Protege

1992 - 93 MX-3 (V-6)

1990 - 93 MX-5 Miata

1989 - 93 B2600

1989 - 95 MPV

1992 - 95 929

DESCRIPTION

If engine noise is heard on initial start up and decreases as the vehicle achieves normal operating temperature, carbon may have accumulated in the combustion chamber and on the piston tops.

NOTE: Additives in some fuels and continuous "short trips" may contribute to carbon accumulation.

The noise that occurs is similar to Hydraulic Lash Adjuster (HLA) noise. However, unlike HLA, the noise will peak and decrease as the engine rpm increases. Before beginning HLA diagnostics or replacement, perform the carbon cleaning process described in this bulletin.

Vehicles exhibiting the above symptoms should be repaired according to the instructions below. Inform the customer that the noise does not contribute to engine deterioration and the use of gas treatment to prevent carbon accumulation will prevent reoccurence of this noise.

REPAIR INFORMATION

Carbon accumulation can be removed using Mazda Top Engine Cleaner (p/n 0000 77 2025) which is available through your Parts Dept. The cleaner should be induced through the throttle body vacuum port with the vehicle idling. Diagrams are attached to assist technicians in locating the correct port.

Carefully read and follow the instructions that come with the cleaner. Recommended induction procedures are as follows:

Operate the engine to normal operating temperature then turn the engine off.
To inject the cleaner into the engine, use the canister purge vacuum port. This port will allow even distribution of the cleaner. Refer to the following illustrations for the vacuum port locations.
CAUTION: The Mazda top engine cleaner must be fed into the engine through the correct vacuum line and at a feed rate of not less than 1.5 minutes per half container with an orifice (p/n E5B6 13 986) in the feeding hose. A faster feed rate may result in liquid accumulation in the cylinder resulting in hydraulic lock-up and engine damage.