QSM 670/2100 hrs – what would you do?

[Larry Backman]

In light of the others QSM thread – Here is a photo of my 3 year old QSM with 2100 hrs.

To me it says the beginnings of a soot leak which I intend to address this winter. I will Have both coolers pulled and serviced, and proactively replace the manifold and gaskets.

The engine has burned about 9000 gallons of fuel, ie low duty cycle and is typically run either at 860 RPM/2.5 GPH or 1875 RPM/18 GPH. In mid summer / heavy canyon load situations for the first 3 hours or a trip it’s probably 1875 RPM/18.75 GPH.

I hate to say it but I now consider the manifold a 2000 hr wear part….

Topic

[Richard Lynch]

QSM 11 Coolant Leak from Coolant Exchanger Plate

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.

[Steve Lewis]

Thank You!

Richard,

Thank you for sharing. It is encouraging to see that, at least from my perspective, there is still some speed to give. I have a Gas powered 40 Sundancer and I am happy with 20kts(23mph) so being able to remove more pitch to get the burn down on either of the QSM options I am looking at, and still stay in my “Acceptable Performance” envelope with a larger boat seems like a possibility.

Both the 480MY and 52SB are in the same local geography of Michigan. I will go take a look once things are open to the point that it is safe or reasonable.

Cheers!

[Richard Lynch]

Sea Ray 52 Sedan Bridge (DB) Performance

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…

[Steve Lewis]

revisiting this thread for a question

Richard Lynch,

There are 2 yachts on the market that I am looking at. A 2004 480MY and a 2006 52 Sedan Bridge. Both powered by QSM’s. For your 52 SB what is your speed at your previously published 2000rpm 20.5GPH/engine?

The owner of the 480MY is indicating 26mph speed with 42GPH total @2000rpm. So 21 GPH per engine @ 2000. With the 480MY I can definitely afford to remove 2 inches of pitch to get the fuel burn into the desired range yet still maintain an acceptable speed for my intended Great Lakes cruising use. Eventually the GReat Loop.

As a comparison, I am wondering what kind of speed you are getting at 2000RPM and 20.5GPH? By removing another 1-2 inches of pitch, would I get ~22MPH running the 52 at 2000RPM and maybe burning 38GPH? Fully loaded with Fuel and Water of course…………

I am trying to reason a few things out from a long term cruising perspective. Both yachts have the 2 full stateroom layout and have acceptable bridge clearance for our eventual Great Loop cruising.

Before I go look at any 52SB would you be willing to share some more detail on the performance of your boat so that I might be able to extrapolate a few things and determine if I am even willing to go look?

I thank you in advance for any data you are willing to share.

Cheers!

[Larry Backman]

EGT – knowing is better than not knowing

Tony – I am just a user, not a Diesel mechanic but as a user having an EGT gauge in front of me is extremely useful to know what’s going on in load situations.

As we have discussed EGT can move up 50 degrees from normal if your “on the hump”, or conversely drop down 50 degrees from normal with 50 more RPMs.

It doesn’t fix anything, but on my long runs I use it, the continuous GPH reading and the engine load reading to adapt my speed as needed to be at or below my “normal” 975 EGT.

One perfect example is on my overnight chugs EGT shows me that chugging along at 8-9 knots 850 RPMs burning 2.5 to 3 GPH keeps the exhaust gas at 4-600 degrees, if I get greedy, bump up to 11 knots, 1200 RPM, my fuel burn goes up to 8-10 GPH and EGT is up at 800 degrees. Obviously it’s telling me what I should know, that the boat is pushing into the waves versus a,using at displacement speed, but it’s a good Visual indicator of that.

[Tony Athens]

#1————-You are dealing with a exhaust manifold design that was “doomed to failure” from Day One in a marine application.. All you can do it mitigate the issues, not fix the base issue. Only way is to reduce overall load, or move the load you need to a higher RPM level by propping down

#2———-Does your vessel cruise speed make you happy using 20.5 GPH? If it does, the move that load up another 150 RPM..That will extend life between “issues”..

#3— An EGT gauge will solve nothing along these line..

Tony

[Richard Lynch]

20.5 GPH @ 2000RPM

Tony:
Since i have trimmed the props and brought the GPH down to 20.5 (from 22GPH) at 2000 RPM’s. What do you recommend as the next steps…? Do you like the below or have different suggestions?

Thank you in advance for all the advice.

1) Install EGT Monitors and try to stay below (X) Exhaust Temperatures maybe by running a little faster to get above the peak temperatures?
2) Assuming i cannot find that sweet spot with speed and exhaust temps…Trim the Props another 1.5″
3) Once i get the above nailed down i would repair/replace the manifolds, install longer bolts, etc.
4) Clean the engine body to monitor for further leaks

[Larry Backman]

Bad leak visual

This is what a bad leak looks like, you don’t want this in your engine room!

[Tony Athens]

If you have lots of top speed of no use, just drop more pitch to move the load HP needed to a high RPM just like on a 715 graph

Doomed to failure=Exhaust design, not the engine.

Larry addressed the “soot thing”.. Your engine is a vacuum cleaner and most of the soot ends up in the aftercooler.

[Larry Backman]

Exhaust leak fallout – from experience

Richard:

I had a bad one 7 year ago. It completely clogged the Aftercooler to the point I got Intake air temperature alarms and derating from the engine on powering up. My engine room was a sooty and almost uncleanable disaster slso.

Steve (and Tony). That’s exactly what I’m doing. MY boat gets 3000# heavier mid summer for a long canyon run, a few years back it got 2000# heavier but more crap keeps getting added….. It needs 19-20 GPH to slide correctly at 20 knots the first 3 hours or a trip. When the boat comes out I want to take another inch out of the prop, move my cruise throttle up to 1950 or so and keep my burn rate down in the high 18s for those 3 hrs, then down to 18 GPH or less on the way home. I’m also doing a keel modification this winter to remove some drag there.

[Richard Lynch]

Un-Educated Question…

Tony:
Sorry, I don’t understand your first sentence.

My intent was to ask if I would harm any engine components by not stopping the small exhaust leaks?

I buy into your experience and advice of reducing the load by reducing prop pitch but after doing so it seems many have found that these engines still struggle to keep the exhaust contained.

So aside from replacing engines what is the next step?

Note I took 1.5″ Pitch out and I am down to 20.5 Gallons Per Hour at 2000 rpm and I did loose a couple top end MPH but not a concern since my top end is 34+ MPH.

Are you saying I should be taking more pitch out and try to get down to 18.5 GPH at 2000 RPM?

When you say these engines are doomed to failure. What specifically do you mean?

Sorry just want to do the best I can with the significant investment i have made into this equipment.

Thanks again for all your great advice Tony!

[Tony Athens]

Richard,

I do not buy your post as to getting the fuel burn down to 19-19.5GPH at a higher RPM.. Look at the attached graph–How’s it done on a 715?

It’s called propping down and if you have the be aggressive, then so be it.

As the all the rest– You are dealing with a design that is doomed to failure.. There is no 100% cure–all you can do is mitigate the issue by reducing the load at the lower RPM.s and moving that needed load up 200++..Yes, you will loose WOT RPM speed, but YOU need to decide what is important to you, not the prop guy and his lacking of really understanding your engine.

1 user thanked author for this post.

Richard Lynch

[Richard Lynch]

Un-Educated Question…

So I have 2007 QSM11 670HO’s. I have read alot of the data on this board and I know many (including myself) of the Sea Ray folks have made the recommended changes (reduce pitch) to reduce load to the magic 19GPH or so at 2000 rpm. This is a difficult task to get to 19GPH @ 2000 rpm for our 52 Sedan Bridge boats. The few/many that have trimmed props, replaced gaskets, manifolds, longer bolts, added exhaust temp gauges, etc… are still having exhaust leaks shortly thereafter as I understand.

All that said, here comes the un-educated question; if we reduce our load and watch the exhaust temps as recommend but let these mild exhaust leaks go… what is the harm? Will other major issues be the result?

of course; Mild Exhaust leaks (carbon monoxide) in the engine compartment is not good but maybe the bilge blowers will pull that out?

FYI – My status – cut 1.5″ of pitch from our props. That reduced the gph from 22 gph to 20.5 at 2000 rpm’s.

– Now debating the next steps.
– – I dont want to waste $5k trimming/replacing the manifolds if they will leak again shortly down the road.
– – I dont want to replace engines or the boat

[Steve Lewis]

The Devil You Know

Larry,

An outsider’s point of view. What about keeping your current QSM, doing the Manifold Replacement and other services but then removing 2 inches of pitch from your prop. Your comment about spending 3 hours at 1850rpm could be 3 hours at 2050rpm @ ~19gph. Same boat speed and fuel burn but now you are adding 200 rpm to engine speed and getting all of the benefits afforded those extra revs. You now will probably get a whole lot more hours before the exhaust manifold gives in, you spend a whole lot less money on the fix and you get to continue to enjoy the boat you know and love(?).

Swapping out to the Volvo or the QSL will cost you a pretty penny and time. Then you will need to work out any gremlins to get to a steady state. How long will that take and what will that do to your stress and patience?

I just went through a rather expensive and inconvenient fuel system rebuild. Tank cleaning(2), fuel lines, 2 pump/filter assemblies and 16 new injectors etc. Granted I have gas engines but I am relating an experience. I was furious and depressed while it was all happening and was close to dumping the boat. This was all emotional. Once all of the work was done and the boat was back in service I was very happy that I stuck with it. I now have a rather nicely running boat that can cruise even greater distances on the Great Lakes.

If you tweak what you have you could extend the life of your existing setup without hauling out the “Big Hammer” of replacement.

Your money, time and choice. Good Luck and let us know

[Tony Athens]

Your call, but don’t confuse or compare an HO engine to a MCD engine in my ” posting politics”…. ..

This engine has 15% ++ more usable long term balls than any QSC 600………….For any applications that does not need more than 20 GPH to cruise all day long , then IMO this is the best engine use can use these days based on what I have seen over the past 7 yrs of watching over 40+++ of them……………………The QSL9 has ZERO issues, period..

Tony

[Larry Backman]

Just scanned the specs

I’d be right on the edge, I’d need to be running close to 2000 RPM and on long trips might exceed the 6 out of 12 hours maximum RPM .

I’ve listened to you for 20+ years and one thing I’ve heard time and again on Cummins and all other engines is that you don’t want to be operating at the max. On the top end offering of any specific engine series.

It’s an intriguing thought , I hate to say it but if I were going to ditch this engine and repower again, the Volvo D11-725 would be a lot more appealing than a 450 HP 9 liter.

[Tony Athens]

Larry,

What would I do? For the long term & I was burned out dealing with replacements?

BTW, I’m personally done will all of the dry QSM’s.. To many headaches and too many excuses to make..

Sell the engine and put in the new QSL9 450 rated at 450 BHP MCD.. You’ll never look back……………….

Look at the two latest curves, look at the HP you need to make your “Canyon Runs”, and at the RPM you would like it at, and then you decide what will work better. It will bolt right up to your gear, remove 500 lbs from the bilge, and cut the NVH down by 50+%. Way easier to deal with and you’ll have more space to work in.

IMO, 1995 -ish technology brought directly over from a solid truck engine, and then “pumped up” so it appeals more to the un-informed public that just want some flash on a seatrial , just cannot make it any more in my book.

Tony

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