Official Caterpillar3116/3126 Thread

Those numbers are slightly different for each HP range, so they will need to be modified for the 420 Hp.

let me see if I can find and post, but CAT does publish these curves.
 
Saverio said:
Thanks
I haven't joined boat diesel yet. Really wasn't sure if there was a need. I guess there is...
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I think its worth it, although I let membership lapse until I need something. However, I just looked there. The 420 hp performance numbers are not in the library. Might have to call CAT.
 
Njlarry said:
Fyi caution, I found boat diesel hard to navigate and slow to no response for cat issue questions. Much better and faster responses here on CSR. Also more knowledge posters here. Your results may vary.
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There are some nugget buried in there. Dave used to post a lot, but not so much anymore. The technical libray is good, but join download what you can and let it lapse.
 
dtfeld said:
There are some nugget buried in there. Dave used to post a lot, but not so much anymore. The technical libray is good, but join download what you can and let it lapse.
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It's been a pretty good resource for my QSM11's. There were some technical bulletins that I nor my mechanic knew about; they were non-mandatory and to be implemented at a certain failure or service interval. I have become more informed reading the info however. Things like front seal leaks and exactly what that might mean.....
 
Saverio said:
Not sure where to fin those numbers
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We can plot the boost and EGTs for the 300, 350 and 385 hp variants and get a pretty good ball park of the 420’s #s. These numbers are reference points any way, and you are really looking for trends from your baseline.

So once hooked up, you’ll go and run at various RPM and record your speed, boost and EGT numbers. These will become your baseline #s. It’s best to do this with a known clean hull, as a dirty hull running gear will cause elevated Boost and EGT at a given RPM vs a clean hull.

if anything is amiss it will show up as a deviation from your baseline.
 
So what really is the difference of each version of the 3116 for the different HP. What changes between a 350 HP and the 385 HP? And was there a 420 HP version??
 
Steve S said:
So what really is the difference of each version of the 3116 for the different HP. What changes between a 350 HP and the 385 HP? And was there a 420 HP version??
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fuel I believe - it’s a different tune on the governor and possibly bigger injectors, but that part I don’t know. Pretty sure the turbo is the same
 
Strecker25 said:
fuel I believe - it’s a different tune on the governor and possibly bigger injectors, but that part I don’t know. Pretty sure the turbo is the same
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The camshaft is different and fuel calibration different. I did think the turbocharger was larger though; maybe not...
 
Steve S said:
So what really is the difference of each version of the 3116 for the different HP. What changes between a 350 HP and the 385 HP? And was there a 420 HP version??
Click to expand...

Just so we are clear…we are talking about 3126s. 3116 is a 6.6l engine with coolant cooled aftercooler, were as the 3126 is a 7.2l with raw water cooled after cooler. Very similar, but different enough. Numbers exist for both variants.

I want say the only difference in the 300-420 hp 3126s was the injection system, maybe the fuel injectors, but I’m pretty sure someone looked into it at one point, maybe had it done. I beleive CAT was involved and verified it could be done. Pretty sure it was discussed on CSR.
 
dtfeld said:
Just so we are clear…we are talking about 3126s. 3116 is a 6.6l engine with coolant cooled aftercooler, were as the 3126 is a 7.2l with raw water cooled after cooler. Very similar, but different enough. Numbers exist for both variants.

I want say the only difference in the 300-420 hp 3126s was the injection system, maybe the fuel injectors, but I’m pretty sure someone looked into it at one point, maybe had it done. I beleive CAT was involved and verified it could be done. Pretty sure it was discussed on CSR.
Click to expand...
I was asking about the 3116’s. I was just curious as what the difference was between the various HP versions. I believe there was a 300HP version and a 350HP version. Not sure if there was anything else.
 
All of these engines come in multiple horsepower and torque specs depending on the application, same basic block. Usually rated based on how hard you are going to run the engine. The are created Hp for continuous duty like a tug boat, to light duty/ pleasure where they only run 500 hrs a year max... CAT publishes a specification. The harder you run them, usually the lower the expected life.

here’s a conversation from a 2010 discussing similar

—> http://www.clubsearay.com/index.php?threads/upgrading-the-cat-3126ta-from-350-420hp.33369/

lots of discussion about this on Boatdiesel over the years.
 
Had a water pump belt snap on the port 3116 at 2000 rpm. The over temp alarm went off at the helm fortunately, so I was able to shutdown immediately.

questions:
What causes a belt to snap? I mean specifically.

Is it age that causes stretch and subsequent tension loss resulting in the belt riding up the pulley potentially cutting or nicking the belt?

What frequency should belts be changed? I guess tension and condition should be checked with each outting.

Fortunately I had a spare on board and found it reasonably easy to swap in, but…
I’m changing all belts now, and, cleaning + lubricating the tension glides for the alternator and the water pump tensioner (loosening those off sufficiently was challenging).

My 3116’s have the synchronizer kit fitted to the damper, which needed to be partially removed to get the new belt on. It’s not as difficult as it looks, but I was careful to align the “spindle” when reinstalling as it’s easy to have it horizontally or vertically askew.

For those that have the 3116, does your coolant overflow tank have a tube on its overflow leading to the bilge or not? Mine looks like it should, but doesn’t, and subsequently an over temp fills the coolant overflow container to max and then sprays coolant like a hose across the engine room! Not the end of the world, but what’s cleanup job!

I think I saw some earlier posts on setting the correct belt tension…any rule of thumb I should apply or get the Cat mechanic to do it once and learn from him?

thanks
 
There are two belts. The outer is tensioned with the alternator and inner tensioned with the idler pulley. The inner belt requires the removal of a bracket to change if I remember correctly.
It is very rare a belt will break if it is within service life and properly tensioned. Things that wear the belts is primarily corrosion in the pulley grooves; so, look at those. If the coolant pump seizes or the idler/tensioner pulley seizes then the result will be a broken belt for sure.
 
Glendinning makes an alignment tool for the synchronizer that is $10 and makes the job quick and easy. If your off a little bit, it will wobble and wear out/break much quicker. A must have IMHO. Worth every penny.

the parts are much more expensive.

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