Mercury Optimax compressor failure - Got pics of the bearing just about to fail.

[tomibach]

model year 2007 225hp 600hrs Optimax (two)..severe galling on crankpin journal, scuffing and scoring on lower cylinder walls....had removed them from my engines and tore them down out of curiosity....always used DFI oil from the dealer...warmed them up, and ran them very conservatively....glad I pulled them after reading this forum...see how long the new and improved ones last...bearings seemed tight although the crankpin needle bearing on the con-rod was fouled with metal flakes

[Mr. Demeanor]

I have about 100 hours on my new compressor which is the longest one has lasted for me. I guess the newer ones are black. My new one was one of the first of the new design and is silver but it does say its made in the USA.

Has anyone had a new one fail yet?

[Promax1R]

I have a 2006 225 Opti with 145 hours on it. How can I check the compressor before I have a failure? The engine runs great and I had rather catch a problem before it hits.

[XstreamVking]

Use a stethoscope to listen to the compressor carefully while motors running. Bad internals make a grinding/knocking sound. Remove the belt and rotate the compressor by hand. Should be smooth with no play at the pulley. Have the air pressure checked by a tech for proper psi. I am sure there are more checks with a lap top diagnostic tool also. Hope this helps.

[boaterok]

With all that play at the crank end whats it doing to the other end of the rod to the wristpin bearing and sideloads on the piston. Is there still damage in the topend that is taking out the bottomend of the compressor quicker.

[Wayne Cammidge]

The Lap top will do nothing to tell about the condition of the compressor, only if it is getting hot.

[jmiller165]

Is the compressor something that should get changed out on my '08 300xs regardless of the fact that it is functioning fine to my knowledge. I have never really checked it but from what I have read I need to relieve the tension on the belt and wiggle it around making sure it is still solidly in place? Anything else or should I just take it to my dealer and have it replaced?

[XstreamVking]

If you have over 400 hrs on it, I would consider replacing it with a new one. I have gotten 800 hrs on one before replacing it and as few as 300 on another. New ones are said to be better quality.

[Promax1R]

I was told by a Merc. dealer they changed internals of compressor starting in 2011. They are suspose to be the best ones to date.

[xskeetshooter]

the early ones made in mexico were doomed to fail..i would look at maybe going to higher precission bearing, standard clearance brs are c3, the br will have markings so look, go up 2-3 numbers on clearance ..the higher the c number the more precise it is,,in turn the rod journal will run more true..just a thought...be prepared to pay a lot for a high c number bearing.

[aRocketScientist]

What an interesting problem. My engine light just came on at low RPM, and i found this thread. From the fix that mercury implemented on the compressor, the compressor had a design flaw. The crankshaft was only supported on one side, with one bearing between the belt pulley and compressor piston. From the description of boat/engine combination, it seems to me that the compressor was bogging down at a bad RPM where it was holding large pressures before it was being injected into the combustion chamber. (Notice the damage to the crank shaft is centered on the compression side of the race.) This large pressure in the compressor, and possibly a resonant frequency at that bog down RPM, caused the crankshaft to rotate slightly causing all the force of the piston to be unequally distributed to the inside of the race. Essentially reducing the size or area that the roller bearing were riding on the race, inside only. (Notice the damage starts on the inside of the race where the roller bearings were transferring all the force from the crankshaft to the piston, instead of having an equal distribution over the entire race) The crankshaft race is heat treated to increase it's strength, but heat treating also makes the metal more brittle, causing the heat treated metal to fail in compression on the bearing side of the race. The heat treated surface flaked off, leaving the more ductile (rough looking) surface behind. Adding the bearing to the other side stops the rotation, even if there is a bad resonance frequency, which would also change with the redesign. It's a design flaw, not really a manufacturing flaw.

Back to cruising the internet to see what the check engine light ON my 1998 Optimax means. It actually goes off when I advance the throttle slightly with no audible increase in RPM and comes ON with a slight decrease in throttle position.

[2stroked out]

Todd D is making billet compressor pulleys. They are a little lighter and vented should run cooler.

[2us70]

I have a 2001 225 Optimax which is all original except for water pumps over the years. I don't know how many hours I have on it but it is quite a few. Do I need to think about rebuilding or replacing my air pump?

[XstreamVking]

Have it checked for proper air pressures and possible leaking air the from the air hoses. Some go many, many, hrs. Some crap at several hundred. I have had several compressors last for nearly a thousand hrs before any problems.

[Onetime]

I'm a little late to this thread but wanted to interject here. 4JawChuck is spot on. To the engineers that posted saying it was a factory defect and machined that way I disagree. While I agree with them on the design flaw the failure is due to the case hardened bearing surface flaking off. Have seen this before on many roller bearing crankshafts. The hardened surface, which is 60 RC or better, is being dislodged from the core material. You can go to most any roller bearing manufacturers engineering books and even in a Mercury service manual and see photos or drawings of this exact nature failure. This is exactly what 4JawChuck did. Those photos and descriptions are from manufacturers books. By the way love your screen name "4JawChuck".