[Richard Lynch]

We replaced the manifolds in 2020. We also took 2″ of pitch out of the props to get to the 20gph range at 1950 or so… 

The issues I described in the first post are as of this year. Maybe a result of what your saying but was thinking something else was going on since I was at or very close to that sweet spot…        

[Richard Lynch]

I have a small amount (more on the Port side) of soot showing up behind the exhaust outlets on the hull this year. Do not recall this over the previous few years.  Oil/Filters changed yearly. Exhaust Manifolds replaced 2020, Aftercoolers removed, cleaned, tested Sept 2019. Elbows & Risers replaced 2021.  Valves adjusted in Sept 2019. Installed SBMAR Air Filters in 2020.   Purchased the boat in Aug 2019 with 550 hours.     

[Richard Lynch]

I have had this boat since 2019 with quite a bit of seat time (400+ hours).  This year has troubled me… See below. 

1. Port engine has been burning more fuel (as much as 2GPH) depending on speed all season.  
2. Overall GPH has increased as the season went on…
   1. Which is typical; bottom growth, higher ambient temperatures, humidity, etc.
3. Aug 1st – Cleaned the bottom and running gear. Prop shop checked the props and said a couple blades were bent over slightly. They thought the yard may have done it by blocking the blades during install in Feb. 
   1. They corrected the Port Prop but not much of a difference noticed in Load and GPH on Port Motor. 
   2. Overall GPH came back down and could reach redline but Port Motor still burning more fuel than starboard.
4. Boat sat for a few weeks (most of August) without use.
5. Took two longer trips and slow cruised for both with blow out runs at the end of each. Couldn’t reach redline RPM (2350 rpm Redline I was maxing out around 2150-2200) for both runs. Boat felt sluggish.
6. Thought I may have growth so have tried to make a couple high speed runs but still cannot reach Redline and still burning more fuel than I should.
   1. Back to back trips now I blew the dipstick out and sprayed a small amount of oil. First time it was the Starboard motor, second time was the Port Motor.  Thought maybe the dipstick was not tightened on the first one so I doubled checked both of them but it still did it on the other motor. Just Ironic???

What the heck is going on? No relation to all of these things or do I have something larger going on… I know I need to pull the boat and check the bottom but cant believe after 3-4 weeks after complete bottom redone that I would have enough growth to make a big difference.  Could dirty Air Filters cause any of this? Both blowby filters do not have the Red Indicators popped up.  Any tips to start narrowing the issue would be appreciated.   

 

[Richard Lynch]

My shop told me they had a job, and applied prop speed to a boats propellers and running gear. The owner immediately complained of a new vibration.

Ultimately, they pulled the boat and found the paint was not applied smooth on a blade or two. I think he said a drip had formed.

They cleaned the rough/drip spots and vibration went away.

True story….

[Richard Lynch]

I have no problem changing the Racor filters without filling them, they fill from gravity. 

The on-engine filters have to be manually filled prior to re-installing in my boat. That does the trick though. 

[Richard Lynch]

I don’t think it is reasonable for the Sea Ray 480, 500 or 52DB Sedan Bridge with a QSM11 670HP to tune the props enough to get 20GPH at 2100RPM.

[Richard Lynch]

– Diversified/Bay Shore Marine
– Shore Power Solutions

[Richard Lynch]

Please enlighten me

[Richard Lynch]

See below for discussion points. This is a from another 2006 QSM 11 670HO and SR 50 Sedan Bridge

I had Cummins pull down both QSM11 engines raw water coolers, heat exchangers, replace one Aftercooler as the PO replaced on in December 2016. I didn’t really want to have 12 years difference in age of the Aftercooler.

We follows Cummins newest protcall as of April 2018. Pulled manifolds, heat shields, turbos and replaced both manifolds with new rather than sending out to be shaved flat and then fight to reinstall them. All new studs, new spacers, baskets which are really more like metal shims, turbo heat shields.

One of the first things I should note is the props where 28” 32 pitch when we started. The progression of pitch reduction has taken me to 28.5” and the results are as follows. Fully loaded with fuel, water, gear and personal belonging which includes a full liquor cabinet and Highfiled Ocean Master 390 Aluminum center console, full of furl with 40HP Honda on a Hurley H30+ Davit system.

Headed South to Key West run at this time in very calm seas at 2020 RPMs, Port & Starboard indicating 80% throttle with 64%-65% engine load, 20.8 & 21.4 Boost pressure, 20.4 & 20.1 GPH, EGT showing 975/980 degrees fluctuating and 22nmh+-.

Based on my last 20 months of working on the engines, props and running conditions I’ve come to the conclusion that this is about as good as I’m going to get, I can drop the tender off which all in weighs 725lbs.

The boat runs and planes fine. Obviously the extra tender weight is going to be more weight than most run with but I like having it with us all the time when we’re doing lots of outside running along the coast.

My observation about the EGT is you need to stay under 1,000 degrees and most problems seem temperature wise to be more common when running under 1800RPMs. You try and drop back to 1500-1800 to better match comfort when running in rougher water conditions your temperatures shoots up very quickly. Looks to me like I run much better around 2000RPMs than less.

I’ve made 4 pitch adjustments each time think I was going to see considerable change with the EGT dropping and have not found that to be the case. It almost seems like 950-985 is the normal running EGT range I see. I have no idea what you’d have to do to stay in the <900 degree range other than trawl around of operate in much colder northern waters during the summer time.

[Richard Lynch]

Sounds good, another 1″ or so will have to go at the next appropriate time. I am not sure the EGT range to follow but i believe the QSM11 670HO is rated at 1100degree F at Rated HP? I have never seen any other ratings other than at Rated HP.

We live in Annapolis, good luck with your trip and let me know if I can offer any logistical suggestions.

We have enjoyed our long trips in the big boat…from Annapolis up the bay to Still Ponds, Sassafras through the C&D Canal and over to Cape May NJ. Also going the other direction down to Solomons, Salt Ponds up the James River and down to VA Beach.

We do run at 1900-2050 rpm’s often but we are trying to slow down to hull speed more often. It allows us to smell the roses, save a ton in fuel, make a sandwich, and relax.

[Richard Lynch]

REV to include more data…

Tony/Steve:
I have a 2007 Sea Ray 52DB Sedan Bridge with the QSM11 670HO Engines. I have taken just about two inches of Pitch out last September (28×32.08″ down to 28×30.5″) with a nice 2GPH improvement in GPH at 2000RPM…. I am currently at 1950 rpm @ 20.5gph

Before Prop Pitch Reduction
Sep2019 3/4 tank fuel:
Props 28″ x 32.08″
-2100rpm 30.5mph 25gph
-2000rpm 29mph 22gph
-1900rpm 25.4mph 20.9gph
– 1700rpm 19.7mph 19.7gph

Pitch Reduction:
Oct2019 3/4 tank fuel
Props 28 x 30.5″
-2100rpm 30.1mph 22.6gph
-2000rpm 26.8mph 20.8gph
-1900rpm 24mph 19.4gph
-1700rpm 18mph 16.5gph

Question is, do I need to take more pitch out? According to the <20GPH @ 2100 rule I have a long way to go.

Appreciate the input and I do wonder if the engines / manifolds are happier at 1800 or 2000rpm’s? We do plan take longer and longer trips. This summer we had several 400+ mile trips and hope to continue and expand on that…

Rich

[Richard Lynch]

Tony/Steve:
I have a 2007 Sea Ray 52DB Sedan Bridge with the QSM11 670HO Engines. I have taken just about two inches of Pitch out last September (28×32.08″ down to 28×30.5″) with a nice 2GPH improvement in GPH at 2000RPM…. I am currently at 1950 rpm @ 20.5gph

Question is, do I need to take more pitch out? According to the <20GPH @ 2100 rule I have a long way to go.

[Richard Lynch]

Realized on our 220 mile round trip run from Annapolis MD to Cape May, NJ. last weekend that I was losing about 2 Gallons of coolant into the bilge every 3 hours or so of running. We were in the first leg of the trip when I realized, so I continued to fill the Coolant Tank every couple hours of running.

Had our mechanic pressure test the system today and he figured out the Heat Exchanger “plate” was weeping pretty good when he applied about 15psi.

We have been planning to have the Manifolds, Bolts, Gaskets replaced to seal up a pretty bad exhaust leak on the Starboard side so now we are forced to move forward and fix the leaking Heat Exchanger Plate while we are in there.

Wondering of any lessons learned on the Heat Exchanger coolant leak you guys may have…?

Thank you in advance.

[Richard Lynch]

Steve:
To answer your question I am typically running 23 knots (26 MPH) at 2000 RPM and 20.5 GPH. This is with 75% fuel and water.

To get down to this I removed 1.5″ Pitch +/- from 32.30″ down to 30.8″… I lost 1.5 MPH or so…

[Richard Lynch]

You may be exactly correct however I am aware of the QSM11 Dry Exhaust Manifold leaking issues. I have those as well. I have posted many times of that topic and posted my before and after prop adjustments. Maybe a little over propped still but I have taken 1.5″ of pitch out and reduced my 2000 RPM GPH from 22.5 to 20.5 range.

Again you might be right and these issues are one in the same however I can feel the exhaust coming directly from the Turbo (Exhaust side) Heat Shield on the Starboard engine. I can NOT feel the exhaust blowing through the Turbo on the Port motor. It does feel like the air (exhaust) is coming from both side but I have not removed the heat shield yet. My mechanic suggested that removing that heat shield is tricky and you can easily distort or damage the heat shield. He is trying to get me on the schedule however i am looking for some history and lessons learned on this issue.

Anyway, i do plan to address the exhaust manifold leak issues at some point down the road.

If someone can shed some light on the Turbo (Exhaust Side) Leaking and what that repair entails i would appreciate it.

[Richard Lynch]

See attached.

[Richard Lynch]

Richard Lynch wrote:

Are there any success stories out there?

What I mean is every QSM owner I have ran into that has attempted to mitigate the damage by reducing pitch, watching the Exhaust Temps, etc…still end up with leaking exhausts after spending $5 thousand (+) dollars replacing or trimming manifolds adding longer bolts, etc

I have also trimmed my props in hopes of reducing load, GPH, Temps, etc.

I am not trying to be negative I am just searching for a long term solution.

SBMAR Team:
I spoke with a Cummins Marine Territory Manager from my area last week. He has been with Cummins for 20+ years and was very willing to hear me talk about what I know and my current set up. At the end of the my soap box speech I asked him the burning question (at least in my mind)…what position does Cummins take in the Dry Exhaust issue of the QSM 11.

His response was that Cummins has a NEW Gasket to address these leaks. He also said I was going down the right path by reducing load and re-torquing manifolds and exhaust elbows. He did say once they start to leak exhaust you will not correct that until re-surfacing/shaving/replacing the manifolds.

Once I clean the engine a bit and confirm that the exhausts are still leaking (I know they are) then I will start to budget the new manifolds or at least “New Gaskets” and re-surfacing.

Note – I have reduced pitch by 1.5″ and currently running 2000 RPM and 20.5 MPG with a heavy load.

[Richard Lynch]

Are there any success stories out there?

What I mean is every QSM owner I have ran into that has attempted to mitigate the damage by reducing pitch, watching the Exhaust Temps, etc…still end up with leaking exhausts after spending $5 thousand (+) dollars replacing or trimming manifolds adding longer bolts, etc

I have also trimmed my props in hopes of reducing load, GPH, Temps, etc.

I am not trying to be negative I am just searching for a long term solution.

[Richard Lynch]

Richard Lynch wrote:

Seems there are a number of us QSM folks with Dry Exhausts…

No fix seems available to me after all the reading I have found.

Question 1 – What does Cummins suggest after all of these years of common issues with the dry exhausts?

Question 2 – I have seen some threads on a Wet Exhaust Conversion. Is there hope for a resonable conversion?

Thank you for your responses

Any thoughts?

[Richard Lynch]

Seems there are a number of us QSM folks with Dry Exhausts…

No fix seems available to me after all the reading I have found.

Question 1 – What does Cummins suggest after all of these years of common issues with the dry exhausts?

Question 2 – I have seen some threads on a Wet Exhaust Conversion. Is there hope for a resonable conversion?

Thank you for your responses

[Author]

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