Official Caterpillar3116/3126 Thread

mrsrobinson said:
Never thought to turn the fuel lines off when I winterized, so no changes there. Stumble is a good word for what it did though, it acted like it was going to fire right up, then struggled a bit, after three or four tries it hit. I had to bump the idle up a little bit to keep it running. It acted like it did when I changed out the fuel filters and had to prime it with the pump.

I watched the exhaust when it first started and saw all the antifreeze blow out. The flow seemed good. I went back to the helm to check some things, came back, and the flow seemed weak and I could hear the whistling noise.

Yes, just sucking in antifreeze for the winterization. No, nothing disconnected. I just remembered that's the engine that's been losing antifreeze. I found where I think it's been dripping when I winterized the engines, posted some pics here, a few of you told me to tighten up the clamps on the hose, so I did before starting it.
Click to expand...

Quite sure this has nothing to with the stumble. Just want to ask if you have been checking the antifreeze level in the "tank" and not relying on the overflow tank level.

I ask because of my experience when buying my boat. I did a cursory check of fluids before the CAT surveyor arrived, all looked good to me. The CAT surveyor opened the reservoir tank on the port motor and topped it off with 1/2 gallon of ELC before he started it up, said he never trusts what's in the overflow, a pinhole leak could screw up the system.
 
Hello, i have a 1997 450 sundancer with 420HP cat 3126(B) not sure what the difference is, between 3126 and a 3126B?
i would like to have å. spare impeller, but not sure what to buy.
Does anybody know what kind of impeller this engine uses?
 
Marius Thorsen said:
Hello, i have a 1997 450 sundancer with 420HP cat 3126(B) not sure what the difference is, between 3126 and a 3126B?
i would like to have å. spare impeller, but not sure what to buy.
Does anybody know what kind of impeller this engine uses?
Click to expand...
I found this with a Google search:

Although the same displacement, the 3126 and 3126B are different engines. The 3126B does not suffer from the same type of block problems that the early 3126 mechanical unit injector engines had. There are a number of differences between the 3126 and the 3126B, most important are a rear mounted turbo, cross flow three valve cylinder head and the addition of the HEUI (Hydraulically actuated, Electronically controled Unit Injector) fuel system.

and

The 3126 engine is the older version of the two and it uses mechanical unit injectors driven off the camshaft with pushrods and is therefore old tech and completly mechanically controlled.

The 3126B is a new electronic version of the series using a computer to control electronic injection system. There are other updates and changes to some of the systems but they both are in line sixes and displacements are identical.

The major issues with the 3126 were on the earlier production engines and are well documented. There are many of these engines in service and most run well - others do not -but this can also be said about most any other marine diesel series out there today.
 
Steve S said:
I found this with a Google search:

Although the same displacement, the 3126 and 3126B are different engines. The 3126B does not suffer from the same type of block problems that the early 3126 mechanical unit injector engines had. There are a number of differences between the 3126 and the 3126B, most important are a rear mounted turbo, cross flow three valve cylinder head and the addition of the HEUI (Hydraulically actuated, Electronically controled Unit Injector) fuel system.

and

The 3126 engine is the older version of the two and it uses mechanical unit injectors driven off the camshaft with pushrods and is therefore old tech and completly mechanically controlled.

The 3126B is a new electronic version of the series using a computer to control electronic injection system. There are other updates and changes to some of the systems but they both are in line sixes and displacements are identical.

The major issues with the 3126 were on the earlier production engines and are well documented. There are many of these engines in service and most run well - others do not -but this can also be said about most any other marine diesel series out there today.
Click to expand...


Thanks Steve, i see on my motor plate it says 3126 and not B, i guess previous owner didnt know.
Du you know what kind of impeller this engine uses?
 
Have anybody heard of 3126 420HP, rebuilt into 450HP engine, if this is possible what du you need to do?
 
Marius Thorsen said:
Have anybody heard of 3126 420HP, rebuilt into 450HP engine, if this is possible what du you need to do?
Click to expand...
Marius, yes there is a 420
HP version of the 3126. Never heard of a 450 HP version but that doesn’t mean much. @ttmott (Tom) or @fwebster (Frank) May be able to answer this question. Frank is a real Cat guru.
 
Steve S said:
Marius, yes there is a 420
HP version of the 3126. Never heard of a 450 HP version but that doesn’t mean much. @ttmott (Tom) or @fwebster (Frank) May be able to answer this question. Frank is a real Cat guru.
Click to expand...
New one on me. Remember - bright flame = short-lived candle.
 
ttmott said:
New one on me. Remember - bright flame = short candle.
Click to expand...

Correct. Here is an article that goes into some detail about the subject.
Bottom line is a 7% increase in horsepower isn't going you yield much, other than a lot of broken parts.
The hull design is really what drives the sweet spot of appropriate engine HP and propeller combinations.
 
The 3126 marine engine came in 3 versions, 350, 385 and 420 hp, all at 2800 RPM. I’ve heard of people attempting to go from a lower hp rating to a higher one, but nothing to exceed 420. This engine probably came in lower hp variants for other uses/ duty rating. The 3116 when down into the low 200hp range for continuous duty applications

But as Tom points out if you crank more power out of a given displacement, you get shorter lifespan out if it.

IMG_0819.png
 
Thanks a lot for quick reply. This is more logical, the previous owner claimed that they were tuned up to 450, like the 3126B engine.
Only that my engines are white and not yellow.
 
Marius Thorsen said:
Thanks a lot for quick reply. This is more logical, the previous owner claimed that they were tuned up to 450, like the 3126B engine.
Only that my engines are white and not yellow.
Click to expand...
Yes, the white is the marine paint version.
 
A now deceased CSR member got an independent mechanic with Caterppillar experience to reset his injector timing to get about 450 hp out of a pair or 3126 Cats. We had a long debate on the advisability of making such a change. One of my favorite things about the unit injection system Cat engines is their efficiency and durability. I had a pair of 3116's with the unit injection system in a 450DA and ran them for 27 years and handled my own maintenance. I only had the Cat dealer on the boat for the 250 hour, and 1500 hour recommended serivce. Both were a basically to reset the overheads (reset the valves and injector timing which require special gauges and tooling, for 2X in 25 years I didn't think it was worth investing in the specialized tooing.

The 3116 and 3126 are extremely efficient power options for a vessel the size and weight of the 450DA. I was against such a change that meant having to run the very stable and durable 3126 at higher rpms. The 3126 has a recommended cruise rpms of 2400 rpm. The only way you can net any useable power gain out of the 3126 is to increase the cruise speed to a higher cruise speed than Cat recommends. Their rpm recommendations are determined based on Cat's performance ratings. The 420hp rating is E-rating or high performance and the 420 hp rating is based on WOT or 2800 rpm. Recommended cruise is based on running the E-Rated engines for extended periods at a cruise speeds not exceeding 2400 rpm. Exceeding that would mean overloading the engines and potentially overheating them…..overloading and overheating are the kiss of death for a diesel engine.

So is shortening your engine life worth the added repair and fuel costs just to run the engines at a higher rpm setting then a than the manufacturer recommends? Never made sense to me……………..
 
fwebster said:
A now deceased CSR member got an independent mechanic with Caterppillar experience to reset his injector timing to get about 450 hp out of a pair or 3126 Cats. We had a long debate on the advisability of making such a change. One of my favorite things about the unit injection system Cat engines is their efficiency and durability. I had a pair of 3116's with the unit injection system in a 450DA and ran them for 27 years and handled my own maintenance. I only had the Cat dealer on the boat for the 250 hour, and 1500 hour recommended serivce. Both were a basically to reset the overheads (reset the valves and injector timing which require special gauges and tooling, for 2X in 25 years I didn't think it was worth investing in the specialized tooing.

The 3116 and 3126 are extremely efficient power options for a vessel the size and weight of the 450DA. I was against such a change that meant having to run the very stable and durable 3126 at higher rpms. The 3126 has a recommended cruise rpms of 2400 rpm. The only way you can net any useable power gain out of the 3126 is to increase the cruise speed to a higher cruise speed than Cat recommends. Their rpm recommendations are determined based on Cat's performance ratings. The 420hp rating is E-rating or high performance and the 420 hp rating is based on WOT or 2800 rpm. Recommended cruise is based on running the E-Rated engines for extended periods at a cruise speeds not exceeding 2400 rpm. Exceeding that would mean overloading the engines and potentially overheating them…..overloading and overheating are the kiss of death for a diesel engine.

So is shortening your engine life worth the added repair and fuel costs just to run the engines at a higher rpm setting then a than the manufacturer recommends? Never made sense to me……………..
Click to expand...


I totally agree with all of you, the boat cruises perfectly for my use at 2100 rpm, and ca 21 knots. And this feels like perfect cruising for this hull.
It was an earlier owner that supposedly should have made this transformation, but when you look at the engines it doesnt look like it had any big rebuilding of any kind.
Marius
 
You must log in or register to reply here.

Forum statistics

Threads
113,253
Messages
1,429,338
Members
61,128
Latest member
MinecraftRuSwilm
Back
Top