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Old 09-24-2018, 12:40 AM   #1
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About 3116TA CAT Engine

Anyone have any comments on this engine 3116TA Caterpillar?
I'm looking at a boat Mainship 460 that has twins built in 1998 ŗr 1999, with 645 hours.

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Old 09-24-2018, 01:32 AM   #2
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My boat has a later, distant relative of the 3116 (the C7).

My understanding is that the 3116 had some issues around the raw water aftercooler cores (as did the 3126 and also the C7). They can leak salt water into the engine if not closely maintained.

So I would have the aftercoolers inspected (get the cores stripped and pressure tested) if you are looking seriously at the boat. It will cost a bit to do that, but it may save you a lot!! Also, given the age of the engines, presumably by now the owner should have replaced the cores at least once, if not twice, so far (they are meant to be replaced every 8 years or so, it is time based not engine hour based) - so you could ask to see the purchase receipts for the replacement cores?


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Old 09-24-2018, 02:49 AM   #3
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Not an unploughed field on TF, see:
I had a vague memory of European built soft blocks which failed and were replaced under warranty, but it may be another engine. And a US boat might not have Euro engines.
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Old 09-24-2018, 06:22 AM   #4
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Only 35 hours per year? Not necessarily good. Be very curious about the exhaust setup especially sea water back flow potential - Mainship design not always perfect.

In support of Bruce K, a large list of replacement and service items has hopefully been done. Check out for details on this engine. Lots of user info and expert comments can be found there.
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Old 09-24-2018, 06:27 AM   #5
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Originally Posted by BruceK View Post
Not an unploughed field on TF, see:
I had a vague memory of European built soft blocks which failed and were replaced under warranty, but it may be another engine. And a US boat might not have Euro engines.
OP, what HP engines?
The soft blocks were the early engines pre-1998 made in France I believe.
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Old 09-24-2018, 09:32 AM   #6
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The gamble here is that age engine with that few hours. Iíd be super cautious. Those engines have done some serious sitting and short of the mythical engine maintenance log, you donít know if they were laid up properly for the off time. I donít like low hour old engines.
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Old 09-24-2018, 07:50 PM   #7
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First thing I would do is verify that the hour meters are working. Second thing is make sure the seller has not replaced the meters. 30 hours a year is not much but outside of this crowd most pleasure yachts don’t do more than 50 hrs a year
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Old 09-24-2018, 08:03 PM   #8
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Ditto the comment to see the posts on, where much has been written on the 3116. There was the 'soft block' issue early in this engine's life, but Cat probably handled most of these on warranty. Check with Cat on your engine's serial numbers to see what they have to say. Also, low hours on an older boat is usually not a good thing, as noted above.
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Old 09-24-2018, 09:17 PM   #9
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Links to a Caterpillar marine engine forum. I don't have experience with your specific engine but have been impressed with Caterpillar support in general.
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Old 09-25-2018, 05:52 PM   #10
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CAT 3116ís

Capt. Punch -

The 3116 are very good engines provided they are not overloaded and maintained properly, something that applies to all marine diesels.

The Short Version:
Sea trialing while fully loaded, they should hit at least 2800 WOT as verified with a photo tach. Anything less, theyíre over propped/overloaded and could develop problems. Again, thatís true for any marine diesel.

The Long(er) Version:
Most of the webís horror stories about the 3116 relate to large planing hulls. Sea Ray put them in many 42ís, overpropped, and failures resulted. Based on all my research, the French blocks affected a very small batch of 3126ís, never the 3116.

I agree with the recommendation to have the aftercoolers checked - they ingest crankcase vapors and can foul over time, especially if the required single-weight oil isnít used. But I donít necessarily agree that, regardless of hours, aftercoolers should be replaced every 8 yearís. Mine has been cleaned and pressure tested regularly and is holding up just fine. The 3116 aftercooler is cooled with antifreeze, unlike the later 3126 which uses raw water to deal with the added heat load from the higher hp rating at 420, so it doesnít suffer from corrosion issues.

Rather, the typical weak spot is the wet exhaust riser which traps sea water inside it. Over time, pin holes can develop on the inside and, if it does, sea water leaks down into the turbo. The original risers were stainless steel. Later ones cast bronze which can be identified by the pencil zinc in the side. The permanent solution is a custom dry riser with a thermal blanket.

Otherwise, they are fuel efficient, clean burning, and except for the fuel rack/injector timing, can be serviced by your average mechanically-inclined owner/operator.
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Old 09-25-2018, 06:03 PM   #11
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Old 09-25-2018, 09:35 PM   #12
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I've got a buddy who has 3116's in his boat. The list of problems he has had is long. A mutual friend who is a Cat mechanic warned him not to buy the boat. He didn't listen and it has cost him many thousands of $$$.
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Old 09-26-2018, 07:08 AM   #13
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I had a pair of 3116s in a 2000 Tiara and the only problem I encountered was a "mid range whine". At certain rpm, the sound was really annoying! Other that that, no problems but I sold the boat after just 10 months of ownership.

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