Replace oil injection drive gear?

[Ross Rains]

I have disassembled my 1998 200EFI to repair a bad rod bearing. When I inspected the crankshaft I noticed the plastic drive gear for the oil injection pump was looser on the crank than I would have expected. The Merc service manual says not to replace the gear unless there is "excessive" looseness. Is there a spec for looseness? Should I measure sideplay or movement in the plane of rotation? Does anyone know what the tolerances should be? This the first post I've ever placed on any forum so I'll ask your forgiveness in advance for any rules I may have broken.

 

[andy6374]

Re: Replace oil injection drive gear?

No rules broken here, welcome to iboats bentrod.<br /><br />You don't want to risk an oil injection failure, so while you have the block disassembled I would replace the pump. Do you know what caused the bad rod bearing in the first place? How do the others look?<br /><br />Others on this forum would probably also recommend that you re-ring and deglaze while you have the block open. I am not very experienced with efi's, so maybe some of the professionals on this forum can give you a hand. <br /><br />-Good Luck<br />Andy

 

[rodbolt]

Re: Replace oil injection drive gear?

if there is no piston damage or bore damage and a careful inspection with the correct measuring instruments confirm all is within specs you can reuse the pistons and rings. its not real likly after a rod failure, neither is the possibility the crank is not damaged.<br /> you really should have the crank and the failed rod inspected by a trained professional. the gear is cheap and easy to replace and now is the time to do it.<br /> but at a minimum use a new bottom main bearing at reassy.<br />use NEW rodbolts at reassy. and everything must be CLEAN and oil free on reassy unless specifically called for clean and oiled in the service manual. I always reccomend dissasembling the wristpins for inspection. never reinstall a piston pin circlip always replace them with new.<br />above all do not let you wallet dictate the parts list or another failure is immenint.<br /><br /> but you must find the cause of the rod/bearing failure or it will do it again. as the oil system feeds a common fuel supply on that engine and you indicate only one failure out of six I would suspect dirt from an insect nest or a failing injector.

 

[Ross Rains]

Re: Replace oil injection drive gear?

Thank you, gentlemen. I will, in fact, have to re-sleeve 1 cylinder (#4) and the rod and piston are no longer serviceable. The crank appears to be ok except for the one rod journal. I am considering sending the crank to a company in Connecticut called NEECA that will turn down the scarred journal, size the rod and provide a oversized bearing. Anyone experienced with this company or this repair technique? I have been trying to determine the cause of the failure and had not considered the injector but I certainly will now. My experience base is with the 122/142 cu. in., carbureted motors of the 80's and this is my first adventure into an EFI motor.

 

[rodbolt]

Re: Replace oil injection drive gear?

does not matter, they both lubricate the same way. if one jet out of six on a carbed motor clogs the results are the same, all six reciprocating assemblies will be traveling at the same speed only one will not be adequatly lubricated and due to a leaner burn that cyl will run hotter, guess which assy fails?<br /> mechanical parts on a modern 2 stroke rarely fail just cause. usually if they do it will occur in the first 10-20 hours of opereration.<br /> by the same token a scuffed cyl can take out a cyl due to excessive contamination of the incoming fuel/oil/air charge. even though its EFI it still relies on crankcase pressure and vacum to move the mix from the throttle body to the cylinder. DFI is a bit different.<br /> thats why its critical when any performance degradation is initially noted to find and correct the problem while its sick and before it dies.<br /> I see it at least once a week, well it was running bad but we went anyway and suddenly a rod appeared outside the block, what happened ?<br />never tried one of those turned down cranks, I have used a few rebuilt ones from OCC but usually I hunt about for a decent used one.

 

[Ross Rains]

Re: Replace oil injection drive gear?

You're absolutely right. Thanks for the help.