Thank You Mercury Racing
04-18-2011, 02:56 PM
#51
Registered
Join Date: Feb 2010
Posts: 3
Likes: 0
Received 0 Likes
on
0 Posts
I have had this problem in engines for sand cars. All types to include LS1, LS6 and even Subaru engines. In every event, it has been an injector that is not functioning properly. Why the injector was remaining open was always the pain to diagnose and find.
The scoring in only one cylinder is most likely caused by fuel leaking down that cylinder and washing away the oil as it ran. If the oil itself had become so contaminated that it was insufficiently lubricating, you would have had scoring in multiple cylinders and/or a worse problem such as a bearing going away.
We have had injectors that worked fine on the bench that would still leak down fuel. Further, we have had imperfections in the injector wiring harness that would cause the injector to remain open.
As the motor is out now, it will most likely be solved but if the problem comes up again, it is simply a pain to find and can cause some real motor damage working the diagnosis.
The scoring in only one cylinder is most likely caused by fuel leaking down that cylinder and washing away the oil as it ran. If the oil itself had become so contaminated that it was insufficiently lubricating, you would have had scoring in multiple cylinders and/or a worse problem such as a bearing going away.
We have had injectors that worked fine on the bench that would still leak down fuel. Further, we have had imperfections in the injector wiring harness that would cause the injector to remain open.
As the motor is out now, it will most likely be solved but if the problem comes up again, it is simply a pain to find and can cause some real motor damage working the diagnosis.
04-19-2011, 12:20 AM
#52
Registered
Join Date: Jan 2004
Location: San Diego, California
Posts: 2,777
Likes: 0
Received 6 Likes
on
6 Posts
Fossil fuel:
As I have posted as an idea on another Mercury Racing 700sci having fuel pressure loss and hard restarting, the fuel rail cross connection on this engine is made thru the casting on the intake (supercharger base) manifold.
If you go to Mercruiserparts.com and search with pictures heading then go to sterndrive racing engines, look up the 700sci with your serial number series and click on the manifold (supercharger & manifold) exploded parts picture you can see this cross manifold port and how the two fuel rails connect via this port.
If there were a casting imperfection or crack in the aluminum in the base where the crossover between the two sides takes place, guess what, the fuel and a lot of it under pressure could be pumped into the engine even when the engine is off and not burning the excess fuel. You might want to have Merc Racing guys test this cross manifold port with pressure and test for leakage as I agree that a cylinder score is not going to get that much fuel in the oil but could be a result of the extra fuel wash, especially if its one of the cylinders closest to this cross manifold fuel port.
Just a thought and idea they may want to check for a possible cause.
Hope it all works out well for you and glad Mercury Racing stepped up for a hopeful fix.
Best Regards,
Ray @ Raylar
As I have posted as an idea on another Mercury Racing 700sci having fuel pressure loss and hard restarting, the fuel rail cross connection on this engine is made thru the casting on the intake (supercharger base) manifold.
If you go to Mercruiserparts.com and search with pictures heading then go to sterndrive racing engines, look up the 700sci with your serial number series and click on the manifold (supercharger & manifold) exploded parts picture you can see this cross manifold port and how the two fuel rails connect via this port.
If there were a casting imperfection or crack in the aluminum in the base where the crossover between the two sides takes place, guess what, the fuel and a lot of it under pressure could be pumped into the engine even when the engine is off and not burning the excess fuel. You might want to have Merc Racing guys test this cross manifold port with pressure and test for leakage as I agree that a cylinder score is not going to get that much fuel in the oil but could be a result of the extra fuel wash, especially if its one of the cylinders closest to this cross manifold fuel port.
Just a thought and idea they may want to check for a possible cause.
Hope it all works out well for you and glad Mercury Racing stepped up for a hopeful fix.
Best Regards,
Ray @ Raylar
