6/1/2003
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How can the distributor cause damage to a freshly rebuilt engine?
How can the distributor cause damage to a freshly rebuilt engine?
According to the AERA technical committee, cracked magnets in distributors on some 1987-2002 GM engines can indeed be a problem. In some instances faulty distributors have been reinstalled after an engine rebuild and caused premature engine failure.
Distributors with cracks in this area (see Figure 1, right) produce erratic ignition timing, driveability problems, detonation and eventual engine damage. These cracks may also have contributed to the original engine failure.
Although the cracks in this photo are extreme, most cracks will not be noticeable to the naked eye. However, even very small cracks will produce spark scatter.
Do you have any suggestions for salvaging worn Cat 3046E diesels?
The AERA Technical Committee offers the following information regarding oversize cam bearings for 1993-2003 Caterpillar 3406E diesel engines. These oversize outside diameter (OD) bearings can be used when cam bores are worn.
These bearings can be installed in any cam bearing position and are available either as .010˝ (.25 mm) or .030˝ (.76 mm) oversize OD. AERA members have reported finding oversize OD bearings in some new engines. Use the chart above to determine the bearings required to salvage damaged cam bores or replace oversize OD bearings installed by CAT.
The successor to the 3406C was the 3406E. Introduced in 1994, and built through the end of 1999, the 14.6L 3406E was for owner-operators, fleets and heavy haulers who wanted performance and fuel economy with unmatched durability, according to Caterpillar.
Today, the 3406E is used as a marine propulsion engine for midwater trawlers, purse seiners, crew and supply boats, ferries and tow boats where locks, sandbars and curves dictate frequent slowing and engine load and speed are constant with some cycling.
We’ve heard complaints of rattles in some GM engines under load. Any thoughts?
The following information should be considered when diagnosing complaints of engine "rattle," "spark knock" or "valve train" noise on 1992-2003 GM 4.3L VIN X and W engines.
This particular noise is most pronounced with the engine at 2,000-2,500 rpm, under a moderate to heavy engine load with the engine at operating temperature. According to GM, this noise is due to a natural torsional harmonic vibration in the cam drive system, which causes loading and unloading of the balance shaft and gear drive assembly.
GM engineering has determined that this noise does not affect the durability of the engine or any of its components. Multiple attempts to eliminate the noise by changing cam drive or balance shaft components may not prove to be successful. It is imperative that all normal diagnostic techniques be followed to determine that the noise is NOT due to spark knock, piston slap, bearing knock or some other noise for which repairs are required.
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