Usage:
G3616 (4CG) ENGINES
Problem:
Early exhaust valve recession has been noted on the above engines which are operating with the 161-1205 Cylinder Head Group (0R-9478 Remanufactured Cylinder Head Group) or the 171-3995 Cylinder Head Group (0R-9752 Remanufactured Cylinder Head Group). These cylinder head groups were released for installation on 10.5:1 and 11:1 compression ratio engines. The 149-0588 Exhaust Valve (made from Nimonic material) is used in these cylinder heads. It has been found that this valve recedes at a faster rate than the Stellite exhaust valve that is used in "pipe line" and "well head" applications of G3600 Engines that are operating at 9:1 compression ratio.
The valve recession is typically noted on the outboard exhaust valve, although, excessive valve recession has been noted on both exhaust valves. Bridge adjustment can be lost if the outboard exhaust valve recedes 3 mm farther than the inboard exhaust valve. Bridge and pin damage has also occurred in some applications when valve recession is not tracked.
Solution:
For these engines, it is recommended that the hours between valve and bridge adjustments be reduced from once every 2000 hours to once every 1000 hours. Also, the exhaust valve recession should be closely tracked.
Note that the maximum exhaust valve recession for the 149-0588 Exhaust Valve is 5 mm. A longer bridge adjusting screw is being developed. This will allow for proper bridge adjustment when the outboard valve recedes at a faster rate than the inboard valve.
A Product Improvement Request has been opened, and a new cylinder head configuration is being developed for 10.5:1 and 11:1 compression ratio applications.
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