Let me tell you a fairy tale of a 2004, 3.0L Mercruiser engine that destroyed itself.<br />Once upon a time there was this Marine Mechanic, that shall remain nameless, that had to replace a 3.0L Mercruiser engine under warranty due to a broken valve that destroyed a cylinder wall and piston. After replacing the long block with a brand new one, the engine was very hard to start, hard to keep running till it warmed up and dieseled severely when shut off, even after idling for several minutes and not over 140° temperature, and there was absolutly no carbon buildup since it was a brand new engine.<br />The timing was spot on, and since this engine had the EST distributor was set at the proper timing per the manual and done while in the base timing mode. Still the same problems. It was obvious the engine was running too lean but with the anti tamper devise on the carb mixture screw, it was impossible to adjust it richer.<br />Knowing the lean mixture was probably the cause of the engine failure, the MM (Marine Mechanic) decided, against his better judgment, that the problem with the engine would occur again in a very short time if not prevented somehow.<br />Knowing full well that the California EPA may rain fire and damnation on him for the rest of natural born life and on into the unknown after death, the MM decided to take the matters into his own hands and remove the tamper proof cover over the idle mixture screw. He soon found this to be a very difficult task, but somehow managed to remove it without destroying the carb or the screw. (He later found it would have been much easier to order a new mixture screw and just replace it and go ahead and break the old one off.) <br />Finally after the success of removing the dreaded seal, he backed the mixture screw out approximately a quarter to a half turn. the engine then smoothed out and ran great, idled smooth and slower without dieing and was even easy to start for the first time in it's life, even cold, and never dieseled again when shut off. <br />While the MM is worried about the hereafter and the consequences of his irresponsible act against the California EPA and all the other mini EPA's of the world, along with the consequences of his complete disregard for the Mercruiser procedures outlined in his service manual, the dastardly dead was done...............<br />The customer, however, wondered why his boat now worked perfectly but the poor ole MM was unable to tell him the truth and worries to this day he will be found out and that upon passing he will be sent to the worst part of purgatory for his serious misdoings, but I will......uh, sorry about that, he will be happy in knowing that the boats engine will now live and last for many trips to the great fishing grounds of the owner.<br /><br />Please understand that this is only a fairy tale and should only be told in the proper company, and hopefully someone will not irresponsibly put this in a vault or something silly like that as it should NEVER be mentioned again as someone else may try it and also be condemned to eternal damnation of the EPA gods.<br />
<br />Might try a Dreamal tool with a cutting disc. They are metal covers.