CAT 3116 vs CAT 3126 in 44 Express Bridge

[Reelsly]

I've been looking at the 44EB for a few years and finally ready for the plunge. Can anyone provide me with some opinions of the CAT 3116 vs the CAT3126? Other than the obvious hp differences, what can the forum tell me about the two motors? I've read/heard that both had problems in the beginning but were usually fixed under warranty.

I'd also like to know if anyone has actual fuel burn / cruising speeds numbers. The brokers I've been speaking with all tell me different numbers and the owners don't seem to know much more. The 3116's do not seem like they would have enough power.

Thanks in advance.

 

[fwebster]

The 3100 series engines had several problems….all were caused by vendor quality issues; not engine design problems. There were some soft valves (caused valves to break under load - totaled the engine) and some soft engine blocks on the 3126 (caused premature cylinder wear) All of those problems were warrantied by Caterpillar and occurred fairly early in an engines life. Caterpillar decided in about 2005 that all the engines that were going to fail had done so or had served a normal useful life so they stopped covering the repair cost. In real terms, if an engine had either major problem mentioned, you would know it by about 125 to 150 hours of running, so any engines you find out there now are well past the time to worry.

Both the 3116 and 3126 are work horses but like every diesel engine made, do not like overloading or over-heating. Stay in the load and temp. "pocket" and they are great engines. They are the same engine family based on the same design but the 3126 has a slightly larger displacement and a seawater cooled after cooler, as opposed to the jacket cooled one on the 3116. Around a dock and up to planing speeds, you will notice no difference in performance or boat speed, but at cruise speeds the 420 hp 3126 will be about 2-3 its faster than the 350 hp 3116, but will burn slightly more fuel. At rated cruise speed of 2400 rpm, the 3116 will burn 22.6 gph while the 3126 burns 26 gph. I have fuel burn tables for both I can send you or post at a later time when I am near my desktop computer.

In terms of real use for a pleasure boat, the EB isn't a speed demon with either engine package and I, personally, wouldn't turn around for the difference in them since 20kts vs 22kts it not that important to me. What you will find interesting is how efficient these engines really are when you figure out there is a sweet spot down around 2200-2250 rpm where the fuel use drops to 16 to 18 gph.

 

[HUMPH]

Frank, I usually run closer to 2400 but dropped to 2250 on a long run to and from SF Bay and it felt different. I don't have flowscans but you think it really drops the fuel burn that drastically? I run a little bow high with full tabs at those RPMs.

 

[fwebster]

Ken,

I found a copy of a spreadsheet I copied from Caterpillar's fuel usage table for the 3116 and 3126. I had to interpolate some values but it is very close to accurate. I"ll send you a copy if you will PM me an email address to use.

 

[HUMPH]

PM sent...

 

[Riptide III]

I agree with Frank. I'm no expert ,however, I just made a 130 mile trip with my 3116 at 2300+ RPM and the math came out to 20GPH

 

[FastMarkA]

In the 450DA w/ 3126s, I just did about 90 miles @ 2300 RPM, and then about ~3-4 hours of trawling anywhere from 1100-2000. That took about 100 gallons.

Here's a little spreadsheet/fuel planner I put together for the 450DA w/ 3126s -- you can certainly customize it for your engines/boat.

https://www.dropbox.com/s/7cc6vphyz1lfj9g/Fuel Burn Worksheet.xlsx?dl=0

 

[merlin]

Frank are those burn rates for each engine or for both together?

 

[JC3]

FastMarkA,
Great post. Thanks for the very nice graph. It is interesting that at Trawler speed, the engine's are burning less than 7 gal per hour. Very nice in this day and age. Thanks again, JC

 

[fwebster]

The numbers I posted are for both engines.

 

[Reelsly]

Thanks for the info. I will obviously get a complete survey but, if you have any other advice, please advise. Are there specific maintenance issues I should ask about? These motors will be about 15 - 20 years old with 1000+ hours. Other than general maintenance and repair, at this point, what should have been done by now? Things like heat exchangers, etc. I've owned a lot of boats but, this will be my first diesel and first above 32'. Thanks in advance for the help.

 

[fwebster]

THe only critical maintenance issue is a valve adjustment and overhead re-set at 250 hours. Beyond that, everything else is regular maintenance. When you find a boat with a complete and accurate service history, it should be worth more than one with no history available. All engine maintenance has a "maintenance clock" and a complete service record lets you verify:

1. Engine oil chanced annually
2. Engine oil filters changed annually
3. transmission fluid/oil changed and filter screens washed annually
4. Heat exchangers cleaned when needed or every 5 years
5. Transmission oil coolers checked for grass annually; cleaned every 5 years
6. Aftercoolers cleaned as needed
7. Seawater impellers changed every 2 years or sooner if local conditions require it
8. Generator sea water impeller changed every 300 hours or 3 years….or more frequently if local conditions dictate it
9. Change generator zinc every 30-45 days
10. Change engine zincs annually
11. Change coolant every 5 years; if no coolant change then annual checking of SCA's must be done.
12. Check condition of and wash and oil Walker Air-sep filter elements annually
13. Change Racor primary fuel filters annually
14. Change engine mounted secondary fuel filters


Every item listed will be at some point on its way to the next interval for service. If no service record is available, then you should do that item when you buy the boat preferably before running it. If you can get the service record, you must identify where each item is on its maintenance clock and compute the cost for bringing current anything due, over due or soon to be due. Your cost for acquisition should realistically include this cost.

By the way, Florida is a big place……where will you locate the boat?

Hope that answers your question………….

 

[Boat Guy]

Frank is the man when it comes to engine issues.

The only thing I will add is that #10, change engine zincs annually, I do every 6 months. Some look a bit worn and others, not so much. Yet I really don't want to try and fish out broken zincs so I find doing them early is cheap insurance.

 

[Reelsly]

Frank,

Thanks for all the info. You've been a great help. I live in Satellite Beach (East of Orlando on the coast). I'll travel a bit for the right boat. Tampa south and the entire east coast of FL. I'll post again when I get closer to the purchase. I'd like to be in by the end of the year.