Cat 3116 Engine problems

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Trichamp

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Dec 25, 2012
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Please share with me problems that I might encounter with a 3116 Cat. Engine. I am looking at 390 Mainships some with Cat. Engines and some with Yanmar. And what are the some of the differences between the 1998 and the 2002 year models of the Mainships? Thanks to all, hope to get into a trawler someday.
 
On a 12 to 15 year old engine it all comes down to the effort applied to ongoing maintenance and a savvy prior owner. For details in gory detail sign up to boatdiesel.com and peruse the tales of each and every diesel brand. Hundreds of threads to pour through will keep you up for weeks.

On the Mainships a savvy prior owner would have successfully dealt with the brand specific issues such as exhaust system design problems (Yanmar) and after coolers (Cat). In both cases improper propping leading to overload will age the engine quickly.
 
The 3116 they put in the Mainships are great. Ours is a 1997, 2k hours with 0 problems since new. We run her easy, 2000 rpm and less. Would not hesitate to buy another.
 
Cat 3116's use straight SAE 30 or 40 CF-4 or higher lube oil as per CAT. No multi-weight oils due to its Closed Crankcase Ventilation system.
See page 91 of https://parts.cat.com/wcs-static/pdfs/PEWJ0074-04.pdf
My friend has a pair of 300 hp versions with 2000+ hrs and they have been flawless since new.
 
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On the Mainships a savvy prior owner would have successfully dealt with the brand specific issues such as exhaust system design problems (Yanmar) and after coolers (Cat). In both cases improper propping leading to overload will age the engine quickly.

The after cooler issue is unique to the 3126, not the 3116. The 3126 uses raw water cooling for the aftercooler, the 3116 uses engine coolant. This change provided for more HP, but also increased the risk of corrosion.
 
And what are the some of the differences between the 1998 and the 2002 year models of the Mainships? Thanks to all, hope to get into a trawler someday.

The biggest difference is that they mysteriously gained 4 feet without getting any longer... In 1997/98, the model was a 35' trawler, labeled Mainship 350. In 1999, it became a 39' trawler labeled as a Mainship 390. Marketing aside, one big difference you will notice is that they removed the little desk at the port corner in the aft salon. Also, the second stateroom went from one large bed that forced the second person to sleep in a coffin to twin berths. Other than those changes, the boat's layout stayed pretty much the same throughout it's 8 year run.

Let me know if you have any other questions, we have owned our boat now for 11 years and it has been great.

-Ron
 
The after cooler issue is unique to the 3126, not the 3116. The 3126 uses raw water cooling for the aftercooler, the 3116 uses engine coolant. This change provided for more HP, but also increased the risk of corrosion.

Cat is very specific in their manuals about cleaning the after coolers on both 3126 and 3116. On the 3116 the after cooler has little issue on the water side as you correctly point out due to being JWAC. Both can oil foul on the air side especially when run at low RPMs for prolonged periods.
 
The 3116 in trawler apps should do just fine. The problems with this engine show up in high speed boats where engine has to run at a high power setting for long periods. Aftercooler fouling from multi-vis oil comes from blowby mist ingested into turbo, and heat of compression in turbo cokes the mist. That plates out on cooler and clogs it.

In trawler service the turbo is barely making any heat so the coking issue is a non-problem. Probably can use multi-vis oil there too, and save some bucks.

The low mounted turbo and exhaust mixer can be a problem, it is harder to get a good elevation on the spill point. Design of the rest of the exhaust system is critical.

I've always liked the way the engines ran. A bit "diesely" as far as noise goes, but that's what an engine should sound like!! Generally cleaner burning than most, and low load efficiency is good.

I think a good match for trawlers, but definitely get the exhaust system checked out.

This is moot if the PO ran it on the pins, as some misplaced trawler owners do.
 
We have a 1996 Grand Banks 46 with 350 hp Cat 3116's turbos. We use the Cat recommended oil; SAEO "Special Application Engine Oil" which is specific to the 3116 and 3126 marine and truck engines and is available from Cat distributors and at most Cat service centers. It is a straight 30 weight. We just bought a couple of cases for $22.00/gal in Florida, which is no more expensive than any good quality diesel engine oil. We have had zero engine problems beyond normal maintenance and now have logged 3,500 hours.

The 3116's that were problematical were manufactured in France and are generically known as "soft block" engines. Most failed in the first 500 hours. Call Cat with the serial numbers of the engines on the boat you want and they can tell you if they are soft block from France. Good luck.
 
We have a 1996 Grand Banks 46 with 350 hp Cat 3116's turbos. We use the Cat recommended oil; SAEO "Special Application Engine Oil" which is specific to the 3116 and 3126 marine and truck engines and is available from Cat distributors and at most Cat service centers. It is a straight 30 weight. We just bought a couple of cases for $22.00/gal in Florida, which is no more expensive than any good quality diesel engine oil. We have had zero engine problems beyond normal maintenance and now have logged 3,500 hours.

The 3116's that were problematical were manufactured in France and are generically known as "soft block" engines. Most failed in the first 500 hours. Call Cat with the serial numbers of the engines on the boat you want and they can tell you if they are soft block from France. Good luck.

We've always used Rotella T. CAT didn't come out with the single viscosity reccomendation until quite a few years after our engine was in service. So she grew up on 15w40 with no ill effects that I can see. We have been feeding her straight 30w for the last 8 years or so.

I don't remember hearing of any Mainships with the soft blocks, I believe most of these were produced before Mainship started using the CATS in 1997 (our boat is the second one produced by Mainship with a CAT).
 
A lot of great information already posted, in the nut shell you need to decipher how the previous owner ran and serviced it, from that you can make an educated decision.
 
As an ex Mainship owner I have been involved with the Owner's group in Yahoo since it started in 1999.

I do not recall any owner having a major issue with the Cat 3116 engine.

There were several issues with the installation of the Cat 3126 series engines (poor exhaust design,water backing up the exhaust system and hydrolocking the engine), but that was a Mainship problem not a Cat engine problem.
 

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