Dropped a valve qsc 8.3 500

[Jonathan Kraft]

Just curious, are dropping valves common on the 8.3 qsc 500?  I’ve heard both yes and know.  Mine was at 1200 hours when it happened.  Also, I’d like to add an egt sensor to my setup.  Does SBMAR sell one?  I’ve been thinking upgrading my instrumentation as well while the motor is out for repair.  I’d like something that would work with the sbmar gauges

Topic

[Jonathan Kraft]

Hey Tony! Thanks for checking in.  All is going well here in cold Maryland.

The motor is out and in the rebuild shop and currently torn down to the block.

Ultimately, the failure point was a failed injector at 1200 hours.  The injector failed and melted the piston.  I sent the remaining injectors out and they were found to be operating but marginally.  There was some black spec of algae found in the injectors as well.  I will note that the boat is equipped with the SMX double double fuel filtration system.  Both the mud filter and the secondary had debris but were showing no restriction on the gauges.  The on engine filter was spotless.

I had to make a decision on how to proceed.  Insurance footed half of the bill to my surprise so I opted to do the works.  6 New Cylinder kits, new turbo, new oil pump, new injectors, rebuilt injection pump, new seals, rods, bearings etc.  The head is at the machine shop now.  I also went ahead and added new motor mounts, SMX gauges, and all new fuel lines to the list.  Given the amount of labor and R&R to get the motor out, I had a hard time justifying just doing the minimum.

Once she is back in the boat, I will create my usage chart that we talked about.  Based on what we talked about and articles on your site, it sounds like I will be shooting for about 16.6 Gallons Per Hour for normal cruise which should be about 2200 RPM.

 

[Tony Athens]

QSC Issues

Jonathan,

I am curious how this all turned out………..

Tony

Seaboard Founder

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1 user thanked author for this post.

Jonathan Kraft

[Rob Schepis]

Good stuff Tony, thanks for posting.

Members – In Tony’s post, be sure to click on the red text or download option for the attachments.  Clicking on the thumbnail itself generates an error message.

Rob
"Luck is the residue of good design."

2 users thanked author for this post.

Tony Athens, Jonathan Kraft

[Tony Athens]

Just because an engine can, does not mean it should 

 

I think you have given this saying  above a new meaning..

Attached are documents on the bottom or put out with  rating curves of how Cummins  has  reworded their ideas on engine duty cycle over the years…

IMO, this to me is  the typical one size fits all type of logic  but if followed by the user mixed in with proper maintenance,   it’s probably as good as something like this can get..

The way I read the Aug 2008 guideline,  which would have been applicable to your engine at that time, you must have totally missed it  (Reduced power must be at or below 400 rpm of the maximum rated rpm.)

I’m sure you will re-think all of this in the future.. And for sure, you will be much happier years from now learning to enjoy more time on your journey , rather than get just getting there sooner.

Think “wine & cheese” along the way.  Hopefully you will do the  Great Loop someday

 

Seaboard Founder

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Jonathan Kraft

[Jonathan Kraft]

Just for clarification and transparency I wanted to put this out there.  Here is why I ran it at 2400. https://www.sbmar.com/articles/proper-propping-specs-of-the-cummins-marine-qsc-8-3-500-hp-engine/

I do understand where I need to run it now.  I just wanted to put this out there for others that run them up 2400

 

 

 

[Jonathan Kraft]

Thank you Tony, you clearly did your homework on this one and now it is time to do mine.  I do have a couple of questions about a few your responses.

 

Re #3:  Based on the continuous duty article, it looks like I should be aiming for a max cruise of about 2250 rpm which puts me at 16.6 Gallons per Hour which is 2 gal per hour per liter.  I am happy running the boat there.  I just was falsely under the impression that the motor could run at 2400 as a high cruise.  I will read theses articles a few more times.  All of this is fantastic info!

 

Re: #5- Yes, I will make the duty cycle chart.  I never run the boat for a 10 hour cruise.  The furthest I go in a day is 3 hours.  That being said, I would say I was running it at 2400 70% of the time.  Once I make the chart. I will have real numbers.   The wide open burst on the way home is usually for about 10 seconds.  Should I stop this all together?

Re:#6- I will get as many photos as I can though the repair process.  What are your concerns with the after cooler?  I would rather do what I need to do now than wait.  You voice your concern, but I am not sure what you are concerned about specifically.  Also, I am also not comfortable with the smart crap setup.  Now that the engine is coming out, I want to make some upgrades.  Would you reccomend the SMX gauge setup?  Would that be the better solution for engine monitoring?  I am willing to make that upgrade.  Should I add the EGT while I am at it?  I realize that won’t fix anything, but is it something I should be monitoring?  To be clear, I am no longer going to run this boat at that RPM.  It is not that I have a need for speed.  I just did not know any better and mpg was better at 2400RPM than 2200 RPM.  Please steer me in the right direction of monitoring the data I need to be monitoring.  I have never had an alarm in my ownership and I believe the previous owner had one alarm due to a failed “Cummins” impeller.  He switched to a SBMAR impeller after that and had no more issues.  I will get someone to hook up to the engine computer.  Is there anything specific I need to be looking for?

7. Yes, Kevin babied the boat, once she is back together that is how it will be run.  He did not have mpg data hooked up and working which is the only reason I ever pushed her to 2400 in the first place.  Lesson learned.

Question- you close with the statement – This is an 8k – maybe 14k vessel at times.  What do you mean by that?

Looking forward to your responses.

Thank you for all of your help and support.

 

[Tony Athens]

Jonathan,

Glad you pulled the valve cover, but IMO you need a lot more than a EGT gauge

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Based on how hard you run  the engine  at cruise, I would immediately pull the valve cover and go thru the valve train twice to see if  you have something “not right” in the cross  heads/ push-rods, valves, etc .  Your symptom seems a tad scary to me. ( repost from before) 

1–You need to re-read your 1st post and dissect it piece by piece so you understand better how you are now at this juncture… The answer is clear but we cannot go back to that first day, as by the time the symptom  was “looked at by the mechanic,”  the damage was already in its early stages.

2——–Now, you have to look at where you are at this point in time and  re-think the long term..

3——Next, this all needs to be put in perspective with how you actually run your engines.   Then  assemble this all  together with a better understanding of these THREE article links specific to what you have experienced…Below IS NOT  a ONE TIME READ and maybe your mechanic could learn something too  about engine loading and duty cycle coupling and learning  “why”  a turbo needed replacing at such low hours. It was not just a failing waste gate. All the external signs of asking too much from this engine were right there looking at him.

Continuous Duty – A Different Perspective

Choosing the Right Diesel Engine for your Boat

Propellers Move Boats, Engines Just Turn Them

4—————— Hopefully, when you spend the time I know you need reading and understanding what is above, you will come to this conclusion……….

YOU HAVE TOO MUCH BOAT and not enough engine for the speeds you wish to travel at.

IMPORTANT NOTE:  Just because a vessel & engine combo can do it,  DOES NOT MEAN IT SHOULD !

My conclusion has nothing to do with the quality of the engine or installation  ( it looks like the installation is OK overall) , but is IMO  directly related to your throttle hand and your  “need for speed.”

5———Are you going to make an accurate  duty-cycle or load chart this weekend?   Put this on your list of things to do—Remember  long term.

Let’s use the last 12 Hours you put on the  vessel — The 10 hours on the ‘last trip,’  and then use the 2 hours running down to the mechanic…  Plot this out like in my examples.  A VISUAL will make this all make sense.

On that last 10 hour run, how much time was spent at you “normal cruise” at 2400 RPM?

“as I always do”–  WOT in this mode. Typically how long is this  “as I always do” –seconds, minutes, ???

6——Let’s be sure good pics are taken throughout  your repair process—Based on all, I am still not comfortable about your aftercooler, and I am very    uncomfortable about how you monitor your engine that is run on the edge of its absolute limits…..  Mercury Smartcrap outboard software was never designed for monitoring high performance diesels in a vessel—just adapted. You have never had any type of alarm code since you owned the vessel?  I’d get a full “print out” from INSITE on the engines history since day one.. It’s all there on your computer.

7———-A close friend of mine happened to know this vessel and past owner and shared some info and links..

Here’s a typical log entry from when my friend owned it.  When my friend took the new owner out for a sea trial the new owner said wow you really baby this thing and my friend told him that’s how an engine lasts for the long term.

https://www.thehulltruth.com/boating-boat-show-photos/1280289-albin-31-thread-new-classic.html

https://www.thehulltruth.com/boating-forum/1339301-cummins-8-3-qsc-repower-fpt-n67-thoughts.html

In the overall interest of this forum and this industry , what is above really needs to be shared so all can learn the pitfalls of running these modern light weight HO engines ( 50HP per liter+)  at their limits.

IMO, this is a 8k – (maybe) 14K at times  “Great Loop” type vessel and should be thought of  just that.

Tony

Seaboard Founder

Go here for the latest stuff we put together and share for all to see:

[Tony Athens]

Jonathan,

All is good–Not to worry.

In your search of other forums, etc.,  if you find anything applicable , forward me a link.

Tony

Seaboard Founder

Go here for the latest stuff we put together and share for all to see:

[Jonathan Kraft]

Thanks Tony, to be clear…. I don’t know much.  I do not claim to know much.  I am a boat owner and not a mechanic.  I’m just trying to find out if this is a known problem or if this is a fluke.  I didn’t mean to share what I heard but I wasn’t sure how else to word it.  That being said, it sounds like you have answered my question.  Thanks

[Tony Athens]

QSC Valve dropping issues

Jonathan,

Since I am in the middle of working with you and your current issue, it would be best for this forum  and me  to to post what  your know, not what you heard. ……………. At this point in time I have doing what I can   to learn if the QSC has a systemic issue with dropping valves and I cannot  find anything.. Please share what you KNOW, not what you heard.

You might consider sharing what I have sent you regarding my thinking and thoughts  on your issue to see what others think ……….. We have some very sharp readers on this forum.

I take no prisoners and if the thoughts on this tend to show this  is a Cummins issue, I’ll have no issue presenting it to them in a proper format.

Seaboard Founder

Go here for the latest stuff we put together and share for all to see:

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