THLWL

Andy,

As per my reply, I said I don't think the problem on 3 of the 4 boats down here was CMI related (in regard to leaking headers). I had 3 potential failure causing issues, not just the lifters. Capt. Call, lifters, and valve guide clearance. Anyone one or a combo of all could have caused my issues. I do know that Norman did change to the Crane severe duty lifters though (like I did). I compared the old to the new, and the Crane looked like a much better lifter. All of the 525's I know about were built in 2005. Just wondering if anything changed during this timeframe on internal parts? Maybe some engine folks on here may have looked at the internals of 2004 and 2005 525 and can provide some feedback.

Tommy

On Time

Thanks, Wild Card, I remember when you put that engine in your boat. Do you go more in fresh or salt water? And if salt what is your flush procedure? What speeds do you get with a 25 ' hull?

Tommy, I have 2005 525's as my boat was put into service 3/4/05. Merc racing says rebuild/refresh on them averages at 6-800 hrs, so they are "good, long lasting motors when they are not abused", whatever that means. He said the '04 and '05 motors were essentially identical.

gerritm

We got the boat back Friday. Here are some pictures of the damaged piston from the #8 cylinder. Also a side by side with the damaged piston from the #8 cylinder on the port motor. Ed, Darrell, and Brent from Clear Lake Power Boat did a great job. Did a sea trial and the boat runs better than ever. We didn't push it too hard, but it has all of the power and performance back.

Here is what we found. Pressure tested the CMI headers and no apparent leaks. #8 had a cracked spark plug. The mechanical fuel pump was bad. Tested the injectors and all were within flow specs. Found some signs of reversion in the #8 header port. Found 2 missing internal flappers on the exhaust tips, but the one from the #8 cylinder was intact. We replaced all of the exhaust tips with new ones with internal and external flappers. Completely rebuilt the top end of the motor. Pistons, rings, valve job, etc.

No defintite smoking gun as to what caused the piston detonation. Did one of the above problems cause a reversion issue or did a reversion issue cause the problem? Your guess is as good as anybodys. I just hope this is the end of these issues for a while. Good to know that I have 2, basically rebuilt motors. The bank book is a little lighter now. We are glad to have " Perfect Timing " back.

tomtbone1993

iTrader: (3)

I would think the bad flappers did not help at all.....

Good to hear your going again

On Time

Thanks for your reply Gerrit. Can't wait to see you out again.

Want to know something interesting? My boat was put in service 3/4/05 and it has the new style "cool collar" CMI headers on the port engine and the old style welded-at-the-flange headers on the STB engine!!

GCAT911

It appears the problom is a combination of factors.Some of the candidates that create reversion> Cam profile, to low of an engine idle, stationary idleing, exhaust pipe geometry and exhaust design. I am skeptical about all the talk about valve guide issues and even faulty lifters. When a specific
fault can not be determined you will find that everything gets placed on the table. Also some piston failures are due to hot spots around the cylinders and detonation. The former caused by a cooling sys prob within the block and generally takes time to take its toll. I am also becoming concerned about fuel blends? We are already seeing how the change in fuel blends is negatively affecting automotive components.

On Time

I agree with you, Frank. The biggest sticking point for me is that EVERYBODY, without exception, had both their engines fail either at exactly the same time, or very short time between. What factors affect BOTH engines at the same time? And it also seems to be worse in salt water. We have been in fresh all summer without incident, and I called the biggest Fountain/Formula fresh water dealers I could find in Austin, Havasu, Texoma and Great Lakes and nobody sounded like they had what we have going on. So I wonder what "combination of factors" is leading to all the trouble?

GCAT911

Andy:
Their is no doubt that with a more aggressive cam like we find in the 525s the sequence between exhaust pulses can allow for a diff pressure that can facilitate flow reversion.This coupled with the other stated factors causes the problom.
Now, once the water enters the engine and depending
on the quantity the dynamic changes. The salt water variable remains unclear other than pure coincidence. If the tipping point is header-metallurgy related than the corrosion factor of salt water becomes a compelling subject. With that being said their are cases of these probloms in fresh water enviros. In your case you may be lucky, at least up to now. Things as simple as the attitued of the boat in the sling or the trailer can let water flow into the engine. As I said
earlier fuel blends are becoming a player in engine probs>> IE detonation. Knock sensors should pick it up and momentarily retard timing, if eng mgt is working? Ethanol is creeping more and more into the blend, not to mention what is being removed. Phase seperation is going to be an issue not to mention the sulpher changes in diesel fuel. Low sulpher in diesel translates into less energy (lower power) and less lubricating abilty to pump and injector internals.
never fear>> its nothing money can't fix.

Frank

gerritm

Frank, we ran all of the codes in the ECM's on both engines and there was nothing unusual. Just some random stuff. No knock sensor codes or anything that showed the engine had malfunctioned. I am beginning to think it may be a fuel issue. Although we ran our boat almost every weekend and bought the fuel from the same place, I am wondering if this fuel is just poor quality.

Gerrit

GCAT911

Knock sensors will not set a history code unless thay have failed. By the look of your pistons it appears that the scoring may have been do to irregular heating. Normaly when we see detonation damge due to uneven combustion over the top of the piston we see actual physical damge across the top of the piston before it takes out the side or ring area. The problom is more prevalent on cast then forged pistons. I think the 555 marine pcm has the capabilty to look at spark advance per each cyl and how it relates throughout the power curve, providing you have the diagnostic software. Take a good look at *CYL IN-LIENMENT> IE>injector pulswidth which is the amplitude and the duration of the injector or how long between on and off. Is the injector spary pattern what it should be? It should be conical in shape. Check for the right fuel pressure and the right fuel trim. Fuel trim is set by the PCM and is always changing. all these factors can be undetecbale by the boat operator but can lead to piston failure. Both the auto and marine indystries are very concerned on how FUEL BLEND CHANGES are going to affect their non FLEX-FUEL engines and fuel systems. And like I said prior>detonation in todays cars is becomeing a bigger and bigger problom even when the fuel mgt sys is working. Now we are seeing the same thing in marine engines