2003 bf 225 pistons all cracked # 4, 5 and 6

Been working on rebuilding my motor the further i get the more i find. All three pistons have cracks between the rings and are all scuffed on the sides. Cylinders all look fine and crank along with bearings look fine. Just trying to find root cause of this damage before i put it back together.all pistons are on the same side dont know if one failed and metal went thru valves and damaged the rest or what. When i broke motor down after failing compression check the cam timing was off, the cams did not line up with the number one on the cam gears at top dead center of number one piston. My thoughts are that the motor was out of time , but does noexplain the damage all on one side. Any thoughts?

You have probably answered the question. The engine being out of time causes a phenomenon known as DETONATION.

Simply stated, it is pressure or hot spots in the cylinder causing the the residual fuel/air mix, AFTER the spark has occurred and started the flame, to ignite. These two flame "fronts" meet in a sort of explosion/collision. This can be very destructive to piston ring lands and crowns as it occurs while the piston is moving upward against the not designed for pressure it causes.

Do the piston tops close to the cylinder walls have a "sand blasted" appearance? That, too, is a sign of detonation has occurred.

The fact that the damage was on one bank only would, at least to me, make it more plausible that timing was the culprit and not fuel.

Low octane or poor quality fuel can also cause detonation because of pre-ignition. That's why it's always best run at least 87 octane (sometimes not readily available in places like Mexico) to avoid this taking place. But, in this case, it would tend to effect both banks not just the one. And, the inner, hotter operating, cylinders would probably exhibit the most damage if fuel was the cause.

No, I think timing is the culprit here and there could be any number of explanations as to why only the pistons on one bank were damaged and not the other. The first one to consider is that only the one cam jumped and only altered that bank's sync. But, we're already way over my head in the failure analysis department so that is where I will end my "thesis".

Good luck with your rebuild.

Yes the sides of the pistons do have the sand blasting effect.thanks for your reply just trying to make sure this doesnt happen again when i get it together.

I don't blame you for wanting all the info you can get. I bet you're sinking a pretty fair amount of coinage into this.

The sandblast thing could be a bit worrisome. The reason I say that is that it usually indicates long term detonation. Each one of those little "dimples" occurred at different times to get that "etched" effect. So, that would mean either poor fuel quality or the engine has been out of sync. for a good period of time. It could just mean that it jumped a tooth initially, ran that way unnoticed for a time and then jumped one or two more at a later date to cause the land damage.

Most engines will tolerate some detonation if it is mild. Have you ever been going uphill in your car on a real hot day and punch the accelerator and hear a clattering or "pinging" noise? That's detonation. Some later model cars will detonate under these types of conditions because of the lean fuel strategies programmed in for meeting emissions regulations. I know of a couple of fairly large cars belonging to friends that have done this for well over 100,000 miles. So, they can take it if it isn't too severe.

As a precaution, if you were running 87 octane or "regular" gas, it might be wise to step up to an 89 octane and run that when you get her back together. The problem with an outboard engine is that, because it is behind you and the ambient noise of the water moving past the hull, you can't always hear all of the sounds the engine is making.

Another factor to consider is, at what temperature was she operating at for the last several hours before your tear down? Have you kept up with cooling system maintenance? Statistically, cooling system problems are factored in as the beginning of 70% of all engine failure. It would be interesting to see what sort of information is stored in the ECM about that and other operating parameters. If you could have a shop with an HDS system hook up and give you a print out of stored data, that could go a long way in helping you solve the puzzle of what exactly took place.

Again, good luck with your project.

Thanks again for the input i have always ran 87 octane. Had this motor to a honda dealer last fall never ran right since i got it back . Wouldnt idle right always surging then eventually would not idle at all, then finally would not even get up on plane. Thats why i decided to do the work myself.the dealer kept telling me it was bad fuel but i always treat my fuel with startron and never had a problem.

You are right, these 200's and 225's are pretty tolerant of fuel variations and I've never had a problem with 87 octane after 1400 hours. The basic enjine is a Honda J35A3, and that is designed for 87 octane. It sounds like Jimmy's thesis concerning timing and pre-detonation is on the money. So once the repairs are made, just make sure the cams and timing are set up perfectly and you should be good to go.