Cat 3116 issues

wickedwheels

New Member
Jul 22, 2019
11
Boat Info
1999 Sea Ray 370
Engines
Cat 3116
I just got my first boat, a '99 370 Sundancer. I found it with Cat 3116 diesels, but I need help with them.

I have one engine that's running a little higher, 190deg instead of 150-160deg with the other one. And the other engine is running slightly higher oil pressure. Someone mentioned that it may be the sea strainers. I'm so green to this that I don't know where they are and how many I should clean. I have 2 ACs, front and back, and a generator. I'm assuming that each one has it's own strainer, plus each engine. Where should I be looking and what am I looking for? Can anyone help out with this?
 
Frank webster is your man. He will respond shortly. You most likely have 1 stained for all the air conditioners combined. Plus one for the generator and 2 large ones for each engine. While that “could” be your issue I doubt it.

There is plenty of information on this site which will get you started in the right direction but here are some basics.

Diesels just need 3 things. Fuel, air, compression. If something is going wrong it can be traced to one of these basics.

1. Keep your fuel clean. Read frank Webster’s fuel management article and follow it religiously.

2 keep your air side clean. The filters should be maintained on a regular basis. And the aftercoolers need to be clean as well to do their job properly.

As far as temperatures out of the normal range. I know diesels but Frank knows this particular engine as well as anyone so I’m deferring to him. He will respond shortly.

Congrats on your purchase, that’s a great boat you found with oil burners! Let’s see some pictures.
 
The parts list will have a pictorial sketch of the bilge area showing the approximate location of all major components on the boat........you will find it helpful.

Cat 3116's have a very robust cooling system so finding one engine running 30-40˚ hotter than the other is unusual and probably indicates a problem you need to discover. Look first at a strainer full of grass or a partially blocked intake. Eventually you will want either clean the heat exchangers or have then descaled on the boat by a local technician where the mechanic has access to a descaler.

You should also change the engine coolant and run a cooling system cleaner thru the engines if you do not have a service record showing when the coolant was last changed. Cat ELC (extended life coolant- from your Caterpillar dealer) has a 6 year life after which it must be changed or extended with the Cat extender which replaces depleted additives and anticorrosives. If after replacing the the coolant and cleaning the heat exchangers you still have this large a difference in temperatures, then you need to change the thermostats. If you change the coolant, you might want to change the thermostats at the same time since you have to dump the coolant to remove everything you need to tho ge to the thermostat housing. Cat has changed the thermostats to 194˚ to improve efficiency and to get a cleaner burn of the fuel charge, so expect the engines to run warmer if you do change thermostats.

The 370DA with Cats is a great boat but it is old enough that you should expect there to be some neglect or deferred maintenance, so hang in there.
 
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Take all of @fwebster advice first, but I'll add one additional data point. I had this same situation on my boat. I had a Cat technician come out and look at the engine ($$$) because if there was a problem I wanted to fix it. He said the engines are running at the same temp, the gauge on the dash is off. The gauge on the engine was accurate. So, you might also check to see if the engines are really running at different temps as you start to troubleshoot.

Everything else that was mentioned is sound advice. Your owners manuals are probably in a big briefcase so you don't dig them out very often. It sounds remedial, but really sit down and read through them - if for no other reason than to understand what they have, so you know whether you can reference them to solve a problem. The Sea Ray owner's manual won't talk about the Cat engines specifically but they will show you the location of the sea strainers, etc. A boat like this can be overwhelming to try and understand if you are new to it. Maybe take one system a week, read the section in the manual and follow the diagrams, then go crawl around in the engine compartment and take apart panels to find where all the plumbing and the wiring goes. It's much easier to build this understanding piece by piece than to try to figure it out under the stress of a problem, on a sunny afternoon, with a bunch of people on the boat staring at you.

I downloaded the manuals and printed out specific pages and posted individual wiring and plumbing diagrams in places where I was likely to need them.

Enjoy the boat!
 
Agree with everything Frank said above, plus it's probably worth taking a look at the impellers, if you don't have the maintenance records of when they were last changed. If you find that they are missing a few of the vanes, they could be blocking up your heat exchanger, causing the one engine to run hotter.
 
Everybody has great advice and points to be made, but if one engine is running at the correct temp 190 and the other 30-40 below that at an incorrect temp isn't that a stuck open thermostat or as someone pointed out a bad gauge...? And on FW's comment about CAT raising the temp on to 194-195, it still freaks when I first look at my engine temp while underway thinking I am overheating, lol
 
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Did your survey identify issues that require immediate attention?
 
Everybody has great advice and points to be made, but if one engine is running at the correct temp 190 and the other 30-40 below that at an incorrect temp isn't that a stuck open thermostat or as someone pointed out a bad gauge...? And on FW's comment about CAT raising the temp on to 194-195, it still freaks when I first look at my engine temp while underway thinking I am overheating, lol

At what temp does the alarm sound?
 
More to Mr. Webster's point, you need to get both engines and gears baselined from a service perspective so you have confidence in the mechanicals and can get into a routine maintenance plan. It's assumed you had a survey when the boat was purchased and any significant findings have been corrected. The Cat 31 series, as Frank states, are designed to run a bit warmer than most other diesel engines so 190 is nominal; your issue is with the cold running engine. So, to everyone's points, have the entire cooling systems (raw water and ELC sides) completely serviced. And another thing, do not expect or assume the gauges are correctly reflecting actual engine conditions.... Hopefully, your engine survey looked at this correlation.
 

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