QSM 11 Exhaust Problems and Engine Fire

[Curtis J McNamee]

I have just experienced the exhaust system breakdown problem on the Cummins QSM 11 670 hp including an engine fire.

My just purchased Bayliner 2002 5788 has been over propped since new and has been run by its owner that way for 3900 hrs. First time out with the boat I had a starboard engine fire due to the deterioration of the exhaust system and blown exhaust gaskets.

Propping these engines correctly is so important !!! I have just had the exhaust systems rebuilt on both engines include new exhaust manifolds….big $$$$

Will now have the props setup according to the recommend fuel burn on this forum.

The engines started to burn to much fuel and are out of specs at 1,100 rpm…below that they were fine.

Excessive fuel burn above 1,100 rpm at various power settings was 17-26%

Topic

[Curtis J McNamee]

Hi Tony- Yes, I totally agree that a lot of mechanics and owners of QSM 11 engines do not understand any of this….the last owner and his mechanic that maintained these engines since new in 2002 had no idea….3900 hrs with no maintenance on the exhaust system or coolers and heat exchangers….

I did post the RPM/fuel burn on this boat from the sea trial on this forum and we all agreed that the boat was over propped.

In the mean time, while waiting for haul out….we had this total exhaust system breakdown and engine fire from a blown exhaust gasket.

The boat is on the schedule for haul out on the 9th, the props will be pulled and repitched to achieve the correct fuel burn per your article.

Thanks for all your help and writing great articles about problems that we are exposed to.

Will repost when the props are done and we can run the boat again.

Cheers,

Curt

[Tony Athens]

Curtis,

New manifolds, turbos, etc etc etc………………Yes BIG BUCKS……………..Other than a simple seatrial at 1000-1400 RPM, I would not even try for a WOT run until you post old numbers and prop dimensions.. Just one 5 minute run on plane on a seriously over over propped “DRY 670” will start the process all over again..

I am here to guide, but you need to listen & let me know what you have..RPM, GPH , vessel speed , and all the specs on the prop you have.

The 670 version was the worst of the bunch as to “fuel curves” that can destroy those particular components..

But with that said, that does not mean you have to prop it that way–That’s what just about all props guys & the overwhelming / vast majority of “dock talk” mechanics do not understand….They have no clue about this engine.

Tony

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