CAT 3116 vs 3126

[FormerBoater]

This question does not pertain to Motorhomes per se, but I have been looking at some boats recently that are powered either by the 3116 or the 3126 depending upon the year of manufacture.

These are mid-90's vintage vessels, so I assume that the engines are mechanical.

I would like to know anything specific to look for or ask about with these engines, and general opinions of the 3116 vs the 3126.

The 3116 engines are rated at 350 HP each, the 3126 engines are rated at 420 HP each.

All insight is appreciated!

[tinkerer]

Correct me if I am wrong but I was told the 3126 was the beginning the 18 valve engine in that series which includes the C7, while the 3116 was a 12V engine. Therefore the heads and other things are different.:@

[Jarlaxle]

A 3126 is a 7.2 litre engine. A 3116 is a 6.6 litre.

The truck I drive at work has a 7.2 Cat, and it is governed to 2600RPM!

[Passin_Thru]

The inline CAT 6s are great engines but the 3116s major defect is the fact it turns 2600 RPM. I never knew of any other CAT engine that turned that fast, D8s turn 1200 and most trudks run 2100 or 1800. I think they are overworked.

[wolfe10]

Sorry, don't know about the marine versions, but we put over 150,000 miles on a 3116 and currently have a 3126 with right at 80,000 on it.

The 3116 was mechanical.

The 3126 (1997 Safari Sahara) is electronic.

Never had any problem with either one.

[FormerBoater]

BobR wrote:
I owned the 3116 engines. In the 1995/96 time frame they did have some bad castings of engine blocks. Failures occurred in the first few years so by now that shouldn't be a concern but I would check the history of the engines using their serial numbers with Caterpillar. Also, the turbos were modified (drilled out) to increase oil flow through them. At the time, it was recommended to use straight 30 wt Rotella for max flow.

As far as problems, I did have to have several fuel injectors replaced. Other than that, no problems. I would check boating sites for other input since marine applications are the much more severe on an engine running 80% load continuously.

As far as fuel consumption, I was running a 40 foot flybridge weighing 26,000 lbs. My cruise was 20 kts and fuel consumption was 1 to 1.2 gpm which in the boating world was darn good.

Thanks for the input, you are right the fuel consumption was darn good to say the least!

I read about the block issues on some boating sights, apparently they were from the foundry in France and would not be an issue now. Read about a few injector replacements as well.

These units are in a 44 foot flybridge with a 28,000 lbs weight, so performance should be comparable.

[BobR]

I owned the 3116 engines. In the 1995/96 time frame they did have some bad castings of engine blocks. Failures occurred in the first few years so by now that shouldn't be a concern but I would check the history of the engines using their serial numbers with Caterpillar. Also, the turbos were modified (drilled out) to increase oil flow through them. At the time, it was recommended to use straight 30 wt Rotella for max flow.

As far as problems, I did have to have several fuel injectors replaced. Other than that, no problems. I would check boating sites for other input since marine applications are the much more severe on an engine running 80% load continuously.

As far as fuel consumption, I was running a 40 foot flybridge weighing 26,000 lbs. My cruise was 20 kts and fuel consumption was 1 to 1.2 gpm which in the boating world was darn good.