QSM11 issues post correct GPH burn

[SeaNile]

Hypothetical question but here it goes. QSM11 engines with anywhere from 600-1400hrs and have zero issues to date despite being over propped and more than the recommended GPH as recommended by Tony Athens and essentially everyone else in the Cummins world.

If you bought this boat and immediately had the props tweaked to get the recommended GPH are the issues with exhaust gaskets and manifolds a thing of the past or would I need to factor in replacing them in the near future?

 

[Gary B]

If the props are cut and you operate the engines cruising @ ~ 20 gph there should not be issues.

 

[SeaNile]

Didn't realize the QSM was such a popular topic on boat diesel. Just cruised through about 130+ posts with great info.

 

[lawndoctor]

SN, as you know from this thread, http://www.clubsearay.com/index.php...ger-and-aftercooler-maintenance-costs.102417/, there are people with QSM-11s who have found that there is no fix to the problem, while there are others with QSM-11s whose experience is that they were able to fix the problem. From this collection of posts, I haven’t been able to discern a pattern between the two outcomes, but maybe others have. Best I can tell is it seems to be luck of the draw. My MAN mechanic in Florida told me he is very familiar with the problem, and the only real solution is to convert the QSM-11s to water cooled manifolds. He said he has seen two examples of that done successfully in southern Florida, but he wouldn’t give me any more information about it. He said the guy who did it doesn’t want to be flooded with inquiries.

 

[quality time]

IMO those manifolds are already warped and will need addressed at some point. I bought my boat with 630 hours eight years ago and there were no visible signs of manifold leaks. I tweaked the props over the first few seasons and still developed leaks during my ownership as the damage was already done. The port engine actually had a blown out gasket and the starboard leak was very minimal but I had them both fixed over the past two winters. We had to skim both manifolds about .040 to get the warp out.

I've said this before but this is really not a big repair especially if you are already in that deep doing aftercoolers which needs done every few years anyway. My cost to repair both and do all aftercoolers was under $10k total, much less than you will pay for MAN maintenance.

 

[Havana Shamrock]

If there was a permanent fix Cummins would have done it a long time ago. Out of all the QSM11 owners here I doubt there’s more than 2 that have “fixed” it. propping, guages,etc. no one here has stated aha!! I found the answer.
I trawled for a year (850) rpm’s with brand new gaskets and they leaked right away explain that one. This time we used a brand new manifold to get some longevity out of it hopefully.

 

[ttmott]

First, the success of the repair on the exhaust manifolds is related to the extent of the repair.
There are two contributing factors to the exhaust manifold leaks - the fueling at load and the bolting of the manifolds. Both are not exclusive to each other.

• The fueling at load is a Sea Ray created issue.
• The revision of the bolting is a Cummins answer to the thermal condition of the manifolds.

There are several things that must be addressed if the QSM11 has developed exhaust leaks -

• The engine fueling must be tailored to 17 to 19 GPH at 1850 RPM realizing 65 to 68 percent load which will significantly drop the EGT's.
• The manifolds must be replaced or trued to the engine head. Pitted and warped manifolds cannot be successfully re-installed.
• The engine cylinder head must be cleaned to the cast iron where the exhaust manifold mates.

• The manifold bolt holes in the cylinder head must be chased and cleaned.
• New manifold bolts and spacers with the short bolts/spacers replaced with the long.
• The fasteners/spacers must be installed with the correct lubricant and torqued in the correct sequence; the bolts must be stretched to account for the thermal expansion rise and fall yet maintain the clamping force.

There are many who had "technicians" replace the exhaust gaskets and then bloviate that the leaks came back and how defective the engines are - ignorant to the needed corrective action that wasn't done.
Then there those of us who technically understood the issues and made the changes which corrected the issue. I personally think that SBMAR doesn't detail out everything that is really needed for the corrective action; they discuss the load but not everything else needed. Boat Diesel is a great resource. But one needs to consider the aggregate rather one or two posts.

 

[lawndoctor]

My cost to repair both and do all aftercoolers was under $10k total, much less than you will pay for MAN maintenance.

I’m close to one year in with MANs and my annual maintenance cost this coming season will be zero. I went over everything with Performance Diesel and they told me I don’t need to do anything this year, just “enjoy the engines.” Not even an oil change since I only put about 100 hours on the oil change last season. I will have regular maintenance (including checking the after coolers) done at the same intervals as I would if I had Volvos or Cats of the same size. Can’t compare directly to Cummins because they don’t make a comparable size marine engine, but the tasks are pretty much the same. If I had QSM11s, in addition to the possibility of having to (a) remove and machine the props to chase the right pitch and (b) remove and machine the manifolds every season or at least on some regular basis, I would also have to (c) tear down and re-lube the after coolers at least every two years to minimize the dissimilar metals problem, none of which I have to worry about with the MANs. So I’m not seeing how it can be assumed that all MANs will necessarily cost more to maintain than all QSM-11s.

 

[ttmott]

 

[ttmott]

remove and machine the manifolds every season or at least on some regular basis, I would also have to (c) tear down and re-lube the after coolers at least every two years to minimize the dissimilar metals problem

Why do you say this?

 

[Havana Shamrock]

Tom we had our manifolds machined, Cummins installed “new and improved bolts,and gasket “ Not a technician. Low rpm’s
I don’t know a single owner that has had it fixed permanently even Cummins own bulletin about the bolts didn’t fix it.

 

[quality time]

I’m close to one year in with MANs and my annual maintenance cost this coming season will be zero. I went over everything with Performance Diesel and they told me I don’t need to do anything this year, just “enjoy the engines.” Not even an oil change since I only put about 100 hours on the oil change last season. I will have regular maintenance (including checking the after coolers) done at the same intervals as I would if I had Volvos or Cats of the same size. Can’t compare directly to Cummins because they don’t make a comparable size marine engine, but the tasks are pretty much the same. If I had QSM11s, in addition to the possibility of having to (a) remove and machine the props to chase the right pitch and (b) remove and machine the manifolds every season or at least on some regular basis, I would also have to (c) tear down and re-lube the after coolers at least every two years to minimize the dissimilar metals problem, none of which I have to worry about with the MANs. So I’m not seeing how it can be assumed that all MANs will necessarily cost more to maintain than all QSM-11s.

My comment was in reference to John's earlier quest into a boat with non-common rail MANs that required testing/replacing injectors every two years. Although I still believe that one MAN service will be more than I have spent on any engine work in eight years of QSM ownership including manifolds.

There is no dissimilar metals issue with the QSM aftercooler and I'd certainly sell the boat if I had to do the manifolds every season. As mentioned I've done it once in eight years and have no reason to believe I will need to do it again during my ownership. No issues in two seasons.

 

[ttmott]

Tom we had our manifolds machined, Cummins installed “new and improved bolts,and gasket “ Not a technician. Low rpm’s
I don’t know a single owner that has had it fixed permanently even Cummins own bulletin about the bolts didn’t fix it.

All good! There are no guarantees; Cummins says minor leakage is of no concern; my "engineering sense of order" drives me. The idea is to correctly implement the fixes which I know you did.
Tom

 

[lawndoctor]

Why do you say this?

As to the after cooler issue, see post #9 as an example of the multiple reports about this problem. https://downeastboatforum.com/threads/any-qsm-11-owners-here.13769/ People refer to the QSM-11 after cooler as a “battery” because of the interaction of the dissimilar metals.

As to the manifold problem frequency, some have reported it regularly and one even said it happened right away after the repair. http://www.clubsearay.com/index.php...ger-and-aftercooler-maintenance-costs.102417/

 

[ttmott]

As to the after cooler issue, see post #9 as an example of the multiple reports about this problem. https://downeastboatforum.com/threads/any-qsm-11-owners-here.13769/ People refer to the QSM-11 after cooler as a “battery” because of the interaction of the dissimilar metals.

As to the manifold problem frequency, some have reported it regularly and one even said it happened right away after the repair. http://www.clubsearay.com/index.php...ger-and-aftercooler-maintenance-costs.102417/

The aftercooler maintenance regiment you are in reference to are the QSB's and QSC's not the QSM's. Plus that regiment is due initially then only as a part of the normal service intervals. With that said if you follow the QSM maintenance schedule problems will be few.
Regarding the manifolds, we have no data to back up what others have said with respect to the means and methods used in the repairs. Someone sent me a message late last year on a repeating leak issue and included pictures of the removed manifolds which were very pitted and reinstalled pitted - twice. They were arguing with their "Cummins" mechanic on the pitting; ends up the mechanic was a technician at their marina and across the board wasn't correctly doing the installation; not even using a torque wrench... So we just don't know how folks on the internet have implemented the repairs.

When you peel back the onion on these higher horsepower engines, I think you will find the QSM11 is comparatively quite economical over it's lifecycle.

 

[SeaNile]

What I am gathering from all of the options out there is pretty much every engine out there has issues. Pick your poison?

The MAN boat I was considering has sold. I think it's a sign because I have never debated about a purchase for that long which tell me I was uneasy about everything. Price was right but in the end I dragged my feet for months and it finally sold.

Looks like the QSM11 is a reality for us since all the 50/52 SD I'm considering have these engines. Hours range from 600-1400 and all are salt water boats.

The search continues.

 

[lawndoctor]

The aftercooler maintenance regiment you are in reference to are the QSB's and QSC's not the QSM's. Plus that regiment is due initially then only as a part of the normal service intervals. With that said if you follow the QSM maintenance schedule problems will be few.
Regarding the manifolds, we have no data to back up what others have said with respect to the means and methods used in the repairs. Someone sent me a message late last year on a repeating leak issue and included pictures of the removed manifolds which were very pitted and reinstalled pitted - twice. They were arguing with their "Cummins" mechanic on the pitting; ends up the mechanic was a technician at their marina and across the board wasn't correctly doing the installation; not even using a torque wrench... So we just don't know how folks on the internet have implemented the repairs.

Agree on the manifold issue, the data is only as good as those reporting it. Having said that, there are lots of people reporting it, and specifically reporting it as unavoidably recurrent, so I’m not sure we can completely dismiss that.

About the after coolers, maybe I’m misunderstanding the situation. After all, you actually own QSMs, whereas I’m just reading about them. From what I have read, the QSM after coolers are mixed metal, and thus have an inherent issue with electrolysis in salt water. To mitigate that effect, lots of grease (specifically, Alco Metalube) must be applied to try to isolate the dissimilar metals. For the grease to be applied properly and achieve the desired effect, the after coolers must be disassembled. This has to be done when the engines are brand new (because the factory doesn’t) and then again fairly frequently (the consensus seems to be 2-3 years) because the grease breaks down or wears away over time, and if not re-applied frequently enough will allow the electrolysis to accelerate again. The electrolysis is never completely checked, but is significantly mitigated by the regular application of fresh grease.

It sounds like you’re saying that is an issue with QSBs and QSCs, but not QSMs?

 

[ttmott]

Agree on the manifold issue, the data is only as good as those reporting it. Having said that, there are lots of people reporting it, and specifically reporting it as unavoidably recurrent, so I’m not sure we can completely dismiss that.

About the after coolers, maybe I’m misunderstanding the situation. After all, you actually own QSMs, whereas I’m just reading about them. From what I have read, the QSM after coolers are mixed metal, and thus have an inherent issue with electrolysis in salt water. To mitigate that effect, lots of grease (specifically, Alco Metalube) must be applied to try to isolate the dissimilar metals. For the grease to be applied properly and achieve the desired effect, the after coolers must be disassembled. This has to be done when the engines are brand new (because the factory doesn’t) and then again fairly frequently (the consensus seems to be 2-3 years) because the grease breaks down or wears away over time, and if not re-applied frequently enough will allow the electrolysis to accelerate again. The electrolysis is never completely checked, but is significantly mitigated by the regular application of fresh grease.

It sounds like you’re saying that is an issue with QSBs and QSCs, but not QSMs?

Correct - The only issue I've noted is a screw was stripped out that held the Hx to the housing and required a Heli coil repair. I think the anode placement in the QSM's cooling loop has a lot to do with the lack of corrosion. My engines had 1200 hours on them when I pulled the aftercoolers, engine heat exchanger, exhaust manifolds, and whatever else was there. But regardless everything in the raw water loop got a healthy coat of Metalube when it all went back together. BTW the aftercooler core is a flanged rectangular unit that sandwiches between the upper and lower halves of the housing; it is not round.

 

[lawndoctor]

Interesting. That’s great to know. Thanks for the clarification.

 

[cod]

Agree on the manifold issue, the data is only as good as those reporting it. Having said that, there are lots of people reporting it, and specifically reporting it as unavoidably recurrent, so I’m not sure we can completely dismiss that.

About the after coolers, maybe I’m misunderstanding the situation. After all, you actually own QSMs, whereas I’m just reading about them. From what I have read, the QSM after coolers are mixed metal, and thus have an inherent issue with electrolysis in salt water. To mitigate that effect, lots of grease (specifically, Alco Metalube) must be applied to try to isolate the dissimilar metals. For the grease to be applied properly and achieve the desired effect, the after coolers must be disassembled. This has to be done when the engines are brand new (because the factory doesn’t) and then again fairly frequently (the consensus seems to be 2-3 years) because the grease breaks down or wears away over time, and if not re-applied frequently enough will allow the electrolysis to accelerate again. The electrolysis is never completely checked, but is significantly mitigated by the regular application of fresh grease.

It sounds like you’re saying that is an issue with QSBs and QSCs, but not QSMs?

The stainless steel pipes that are attached to the aftercooler have “pencil” zincs (see photo below) that control any electrolysis.