35643-ZW4-H01 Honda SEE PART DETAILS - SUP; GROMMET (Honda Code 7758709).

Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.Problem
Illustration 1 g06574711
Illustration 2 g06574712Two cup plugs are used in multiple locations around each cylinder head. 300-4048 Cup Plug is smaller diameter plugs and 8M-5860 Cup Plug is larger diameter plugs. Refer to Illustration 1 and 2.Coolant leaks have been observed from both the small and large cup plug locations. External leaking locations vary and will result in an external coolant leak and loss of coolant. The small plug under the valve cover has been another common leak path, and that leads coolant to mix with the engine oil.Solution
Do not operate or work on this product unless you have read and understood the instruction and warnings in the relevant Operation and Maintenance Manuals and relevant service literature. Failure to follow the instructions or heed the warnings could result in injury or death. Proper care is your responsibility.
Caterpillar is aware of this problem, but an Interim Repair has not been defined. As an interim solution, replace the cylinder head cup plug with the same part number.
Illustration 3 g06574714
Illustration 4 g06574723In the event of a failure, retain the failed parts for a possible "Send-It-Back" request. In addition, provide pictures and additional information along with Technical Information Bulletin (TIB) Media Number (M0121331), CPI Number (472308), Machine Serial Number, origin of leak, and part hours at failure to your Dealer Technical Communicator (TC). Request the Dealer TC to submit the information through CPI Feedback within the Service Information Management System (SIMSi).Also provide the following additional information to support root cause investigation:
Provide the information as shown in Illustration 3 and 4.
Cylinder head part number.
Cylinder head serial number. Serial number will be nine digit alpha-numeric found on the side of the intake connection.
Specific photos showing plug locations that are leaking.
Do not attempt to remove the plugs. Return the cylinder head assembly with leaking plug intact.
Cylinder head component hours and cylinder head source (new, reman, dealer rebuild)
Product Status Report (PSR) with histograms.
Coolant Scheduled Oil Sampling (SOS) history.
Coolant type.Another interim containment action is available for this issue. Follow the recommendations given below.Caterpillar recommends adding 8C-3680 Coolant Conditioner or 217-0617 Coolant Conditionerto the cooling system to reduce or stop the coolant leaks. This action works best when a leak is first observed.When added to Extended Life Coolant (ELC), the coolant conditioner will react to form a silicate precipitate. This precipitate will accumulate in small orifices and low coolant flow locations, like locations created by a leaking liner insert. As the precipitate accumulates, the leak will slow substantially or stop. The process will gradually happen over several weeks of running time.The interface should be cleaned appropriately and monitored during run time to ensure that the leaks are slowed and/or stopped. This coolant conditioner is not a conventional stop leak additive.Caterpillar does not recommend using a stop leak additive. The additive will plug the cooling system and reduce overall cooling system performance.Add one container of the 8C-3680 Coolant Conditioner to the coolant system. The coolant conditioner should be reapplied if coolant is drained and refilled, for the life of the engine. Total coolant capacities very by application, do not exceed a concentration of 2% coolant conditioner to overall coolant volume for your application.The 8C-3680 Coolant Conditioner is to be used in the United States only and the 217-0617 Coolant Conditioner for every other region.