QSM11 issues post correct GPH burn

Thanks. So if I’m understanding this right, Cummins put those on QSMs but not on QSBs or QSCs, and that is why QSCs and QSBs require the regular dissimilar metal maintenance with the grease on the ACs but QSMs do not?

(Edited) Looks like it may have more to do with the QSM AC core being rectangular and sandwiched between the two halves of the housing, as opposed to the QSB and QSC core being a cylinder that is contained in a cylindrical housing with round caps at each end.

 

Note here also on @cod 's engine (port engine) that he has relocated the fuel cooler (where the blue hoses go to) to this side of the engine. OEM the fuel cooler is located under the raw water pump, between engine oil pan and stringer and motor mount on the other side of the engine with a huge steel bracket above it. It has a pencil zinc that simply can't be accessed, nor the cooler serviced in that impossible OEM location. This is a super simple mod to do; only thing is new fuel return hoses need to be acquired. This is the DB configuration; the DA's may be different.
Also of note is after 2008 Cummins eliminated one of the zinc's in the stainless tube between the aftercooler and the engine heat exchanger below.

 

Thanks for the detail. Sounds like a good mod. I’m studying up on the MANs to see if there are any particular issues like that I want to be on the lookout for.

 

Has anyone had to remove Salon floor to get access to Stbd engine to work on exhaust manifolds heat exchangers, etc?

 

Did mine without removing the floor. Not easy but there is room to get it done. That's a big job to pull the floor out of the boat.

 

Not to detract but the last post triggered me reading through this thread. We been having discussions about the mann's vs qsm11's. At our marina the talk is to not touch them and go with the mann's. The other side says mann's are more to maintain even if you compare to remediation cost of the qsm11 exhaust issues. We would really like a 3 stateroom boat but its very hard to justify leaving my very economical 8.3 CTA to deal with warped manifolds or mann maintenance. Maintenance is so cost effective and they are truly bullet proof if cared for. I have noticed however that the few 52 DB that have popped up on boat trader with mann's are priced significantly lower than those with qsm's. Are the the mann's not desired in the 50/52 DB? Also are they diy friendly when it comes to maintenance?

 

They are both great power plants. They both have their quirks and issues as they age. It's more important to me that the service available where the boat is to be kept is the leading factor on which to get. Of course this is premised upon equal condition when acquired. I do think, however, that repair parts for the Cummins are more available in the US.

 

Thanks for the response.

 

Any Chesapeake Bay boaters with thoughts would be helpful. I was planning to have Shore Power Solutions, Kent Narrows, replace both manifolds and go through the entire boat and service whatever needs to be done. They came highly recommended by several people. They said the floors in the salon would need to come up. I haven't heard anyone on the forum say they had to remove the floors. Any thoughts? Any recommendations for mechanics on the Chesapeake?

 

It doesn't sound like Shore Power Solutions have done this work on Marine QSM11 engines before if they say it can't be done with the floors in place. It's a big deal to pull the floors out. Are they aware of the service bulletins on the manifolds? The helicoils that will be needed on the aftercoolers? Are they a certified Cummins service center? One of our members on this forum had his aftercoolers serviced and ended up having to rebuild the engine because it appears the work was incorrectly executed. I'm not trying to spell doom but be informed on getting the service done.

 

You have a great MAN service company right in Mystic, so service is not an issue at all. Both good engines. DIY on the MAN is fine, but I would let a certified tech do the major water system services (A1 and A2). Call Bayside to get an estimate as I suspect the R600's are considerably less than my 900's. If you keep the boat in New England and it's laid up half the year, the A1 and A2 services are good for 4-6 seasons.

I think I would focus more on the actual boat than the engine as either one is a good option.

 

Mike
I have had Shore Power for most all of my major engine work since 2019. They do know what they are doing. Richie, Stosh and Dylan are all solid.

Which model and year boat do you have? I heard someone with a 48’ sedan bridge removed his interior for the exhaust job. I was surprised when I heard that.