Official Caterpillar3116/3126 Thread

[douglee25]

Where do you guys run oil on these engines? I read on boatdiesel that many folks run somewhere around the 1/2 mark so they're not overfilled

There has been some discrepancy over the years in the 31XX series motors on exact oil level due to oil pan differences/dipstick length. They recommend an dipstick calibration to get exact high/low marks. If you don't have issues and you run consistent oil levels, I would not send yourself down a rabbit hole (you'll find conflicting info).

http://www.engineprofessional.com/TB/TB032116-2.pdf

 

[Strecker25]

There has been some discrepancy over the years in the 31XX series motors on exact oil level due to oil pan differences/dipstick length. They recommend an dipstick calibration to get exact high/low marks. If you don't have issues and you run consistent oil levels, I would not send yourself down a rabbit hole (you'll find conflicting info).

http://www.engineprofessional.com/TB/TB032116-2.pdf

I’ll leave it be. Doesn’t consume oil and if I check the level immediately after shutting down its around 1/2 way between the marks. If I let it sit snd all the oil drains back into the pan it shows full

 

[Riptide III]

You should get that oil analyzed. It could be fuel in the oil. There is a chance that fuel has been washing down one of the cylinder walls and is failing the piston rings thus causing the blow-by. Hope not but it's a possibility.

I do that every year. The excess level was my carelessness 100%

 

[Strecker25]

after inadvertently draining 1/4 tank on one side (see previous posts) I tried to draw both engines from my starboard tank to level things out. The port engine wouldn't stay running and had all the indications of air in the lines so I suspect by selector valve has an issue on that side. I took the panel out to see if there were obvious leaks, and intend to tighten everything up just to be sure it isn't sucking air - any other troubleshooting I can do on that valve? It's quite a spider web of hoses behind there

 

[Sgrochow]

after inadvertently draining 1/4 tank on one side (see previous posts) I tried to draw both engines from my starboard tank to level things out. The port engine wouldn't stay running and had all the indications of air in the lines so I suspect by selector valve has an issue on that side. I took the panel out to see if there were obvious leaks, and intend to tighten everything up just to be sure it isn't sucking air - any other troubleshooting I can do on that valve? It's quite a spider web of hoses behind there

Can't offer troubleshooting tips, just wanted to let you know that tightening and/or exercising the valves fixed my somewhat similar issue. The marina's tank unexpectedly ran out of diesel and I ended up with a listing boat.

Used the selector valves to draw off the starboard tank to try and level out. After that, port motor knocked like crazy on start up. I exercised the valves and tightened every fuel fitting that I could see and the problem disappeared.

 

[Strecker25]

Can't offer troubleshooting tips, just wanted to let you know that tightening and/or exercising the valves fixed my somewhat similar issue. The marina's tank unexpectedly ran out of diesel and I ended up with a listing boat.

Used the selector valves to draw off the starboard tank to try and level out. After that, port motor knocked like crazy on start up. I exercised the valves and tightened every fuel fitting that I could see and the problem disappeared.

thanks! I’ll give it a try

 

[Thomas Griffith]

Man, this was a fun thread to go through. I am moving my questions on the 3126 here.

Hello All, just had a survey on a 2001 380 Aft Cabin diesel 3126TA cats. No major issues to report, minor overheating in the starboard motor at higher rpms. It was a dock queen with only 760 hours, but was a liveaboard and has a contracted captain so it wasn't fully neglected.

It's got fresh shaft seals and they have "descaled the engine." The engines surveyed well enough besides the overheating on the starboard side, pressure tests were good, survey report and oil test will be back today.
The overheating happened as we kicked it up. I don't have the precise rpms that started it, but it gradually heated up to overheat over a couple of minutes, not a rapid instant climb. We were able to do 8-9 knots without any issues and was playing with fuel burn at anywhere from 2.2gph to 5.5gph on our regular running. We opened it up three times to get about 18knots before the captain and I felt it was best to back it down and not heat it too far. Taking it back to that 8-9 knots and the engine cooled back down to operating temp within a minute. Didn't see any smoke, engine surveyor didn't see smoke either.

At the moment we are planning to ask the sellers to have the heat exchanger boiled, but wanted to get a few more opinions of what it could be. I suspect a LOT of cleaning parts and replacing hoses and clamps is in my near future if we accept. We did NOT have Cat survey the engines, that option wasn't discovered until yesterday evening, but our surveyor came highly recommended and after observing him do his thing we felt he could charge us more and we wouldn't be upset.
Any after thoughts with the above info?

 

[Jus the two of us]

Thomas,
Welcome to the club!! 8 or 9 knots is almost Idle speed.If it started over heating above that I would be concerned. Save yourself so grief down the road and have Cat look at the engines. With todays Boat prices being so high if you end up doing a bunch of engine work you will be upside down quickly.
Good luck !!

 

[ttmott]

Man, this was a fun thread to go through. I am moving my questions on the 3126 here.

Hello All, just had a survey on a 2001 380 Aft Cabin diesel 3126TA cats. No major issues to report, minor overheating in the starboard motor at higher rpms. It was a dock queen with only 760 hours, but was a liveaboard and has a contracted captain so it wasn't fully neglected.

It's got fresh shaft seals and they have "descaled the engine." The engines surveyed well enough besides the overheating on the starboard side, pressure tests were good, survey report and oil test will be back today.
The overheating happened as we kicked it up. I don't have the precise rpms that started it, but it gradually heated up to overheat over a couple of minutes, not a rapid instant climb. We were able to do 8-9 knots without any issues and was playing with fuel burn at anywhere from 2.2gph to 5.5gph on our regular running. We opened it up three times to get about 18knots before the captain and I felt it was best to back it down and not heat it too far. Taking it back to that 8-9 knots and the engine cooled back down to operating temp within a minute. Didn't see any smoke, engine surveyor didn't see smoke either.

At the moment we are planning to ask the sellers to have the heat exchanger boiled, but wanted to get a few more opinions of what it could be. I suspect a LOT of cleaning parts and replacing hoses and clamps is in my near future if we accept. We did NOT have Cat survey the engines, that option wasn't discovered until yesterday evening, but our surveyor came highly recommended and after observing him do his thing we felt he could charge us more and we wouldn't be upset.
Any after thoughts with the above info?

All of the raw water from the coolers ends up going through the gear cooler then dumping into the exhaust. That gear cooler tends to be a restriction also so make sure they cook it also. Secondly, the CAT engine coolant if not serviced per the CAT schedule will gel out on the cast iron in the cooling jacket and will also restrict heat transfer so I would flush and replace the coolant as one of the first things you do.

 

[Thomas Griffith]

Thomas,
Welcome to the club!! 8 or 9 knots is almost Idle speed.If it started over heating above that I would be concerned. Save yourself so grief down the road and have Cat look at the engines. With todays Boat prices being so high if you end up doing a bunch of engine work you will be upside down quickly.
Good luck !!

We are investigating that today while we wait for our survey report and oil samples to come back. The surveyors total cost was $1500 for general survey and $1000 to do the two engines. He spent 80% of his time in the engine room and doing a LOT of testing on the engine and components. I feel very confident in his assessment being accurate.

That being said, any advice on how to connect with Cat to have them check it? We are in Sarasota, Florida. I went online and called two of the listed dealers and neither seemed to have a basic knowledge enough to inspire confidence, so I didn't even ask them for a quote. Both asked, is it considered heavy equipment or regular machinery. Well, im not the Cat specialist so I had assumed they would be able to tell me the answer to that not the other way around.

 

[Thomas Griffith]

This is the survey summary. We got the RPMs to 2650. That was our "WOT" test.


The following summary and recommendations list reflects those areas and items found during the
course of a non-intrusive vessel survey. Areas or items that requires immediate attention will be

designated: *
1* Address horn, was not operational
2* Address overheating issue from starboard engine, service heat exchanger, after cooler and
raw water pump impeller
3* Address raw water dripping from generator raw water pump area
4* Address generator pre heat system, unit stalls after releasing the pre heat switch
5* Address port vacuflush pump, cycling frequently
6* Address generator oil pressure switch, did not power up
7* Address generator Hertz output 58 instead of 60 Hertz

 

[Strecker25]

This is the survey summary. We got the RPMs to 2650. That was our "WOT" test.


The following summary and recommendations list reflects those areas and items found during the
course of a non-intrusive vessel survey. Areas or items that requires immediate attention will be

designated: *
1* Address horn, was not operational
2* Address overheating issue from starboard engine, service heat exchanger, after cooler and
raw water pump impeller
3* Address raw water dripping from generator raw water pump area
4* Address generator pre heat system, unit stalls after releasing the pre heat switch
5* Address port vacuflush pump, cycling frequently
6* Address generator oil pressure switch, did not power up
7* Address generator Hertz output 58 instead of 60 Hertz

2650 is pretty low, mine were at 2680 when I bought it and I ended up having quite a bit of work to do to get them up to 2850 (prop repitch, aftercooler cleaning, new hoses, new turbos, realign engines, straighten strut = $$$$)

Basics - how does the bottom look? can you turn the shafts easily by hand at the trans coupler? how do the props look, and are the original pitch?

 

[Thomas Griffith]

From the survey: At the time of the inspection the vessel’s bottom was inspected and found to be free of structural
bottom damage and with serviceable antifouling paint coverage. There were some anticipated
minor construction voids noted on the chines and hull flats.
Sacrificial zinc protection on the tabs and transom was aging at the time of the survey.
.
Shafts: 11/2” Material: Stainless steel Propellers: four blades: 24x25
Trim Tabs: 11X24 Material: Stainless Steel Rudders: 8.5”X18” Material: Bronze
Stuffing box type: Dripless, Conditions: No leaks noted


I dont think the prop pitch is mentioned and I didn't attempt to turn the shafts by hand personally. The sellers had the bottom job done and it was clean and new shaft seals done in April this year. There is also an extra set of VERY nice propellers under the VIP berth.

Stecker, I've read your posts extensively and I can tell you I'm not as focused on the numbers as you. I don't know enough about diesels yet to really say either way if it effects it much, but I suspect the more I dig in the more I'll start focusing on the numbers. In the meantime, I am looking to take some Cat classes and diesel classes just for some base knowledge.

But we aren't worried about the rpm's at WOT as much as we are wanting to get that overheating under control at the stated rpms.

 

[Strecker25]

the shaft thing is a longshot, I had a bent strut so it was part of my problem but that's unlikely to be causing any issue in your case.

your props are 25" pitch according to those notes. I'm not sure if those are stock but I suspect they are and SR had a habit of overpropping diesel boats because they sea trialed them without anything on board, 1/4 fuel, no water, etc.

I think you're spot on with getting the overheat under control and re-evaulate. You can also check with other owners of your particular model to see what pitch they're running. As an example, most of us 400/410 diesel owners have gone down to 21.5 versus the original 23" to get to 2850 WOT

 

[Steve S]

From the survey: At the time of the inspection the vessel’s bottom was inspected and found to be free of structural
bottom damage and with serviceable antifouling paint coverage. There were some anticipated
minor construction voids noted on the chines and hull flats.
Sacrificial zinc protection on the tabs and transom was aging at the time of the survey.
.
Shafts: 11/2” Material: Stainless steel Propellers: four blades: 24x25
Trim Tabs: 11X24 Material: Stainless Steel Rudders: 8.5”X18” Material: Bronze
Stuffing box type: Dripless, Conditions: No leaks noted


I dont think the prop pitch is mentioned and I didn't attempt to turn the shafts by hand personally. The sellers had the bottom job done and it was clean and new shaft seals done in April this year. There is also an extra set of VERY nice propellers under the VIP berth.

Stecker, I've read your posts extensively and I can tell you I'm not as focused on the numbers as you. I don't know enough about diesels yet to really say either way if it effects it much, but I suspect the more I dig in the more I'll start focusing on the numbers. In the meantime, I am looking to take some Cat classes and diesel classes just for some base knowledge.

But we aren't worried about the rpm's at WOT as much as we are wanting to get that overheating under control at the stated rpms.

As mentioned, I would get the overheating under control. You do not want these Diesels to run hot. Bad things happen if they get over 210 degrees. They should run about 165 degrees.

The two RPM tests are getting 2850 RPM under load for full throttle while moving. The second is neutral full throttle and you should get 3000 RPMS.

 

[Strecker25]

From the survey: At the time of the inspection the vessel’s bottom was inspected and found to be free of structural
bottom damage and with serviceable antifouling paint coverage. There were some anticipated
minor construction voids noted on the chines and hull flats.
Sacrificial zinc protection on the tabs and transom was aging at the time of the survey.
.
Shafts: 11/2” Material: Stainless steel Propellers: four blades: 24x25
Trim Tabs: 11X24 Material: Stainless Steel Rudders: 8.5”X18” Material: Bronze
Stuffing box type: Dripless, Conditions: No leaks noted


I dont think the prop pitch is mentioned and I didn't attempt to turn the shafts by hand personally. The sellers had the bottom job done and it was clean and new shaft seals done in April this year. There is also an extra set of VERY nice propellers under the VIP berth.

Stecker, I've read your posts extensively and I can tell you I'm not as focused on the numbers as you. I don't know enough about diesels yet to really say either way if it effects it much, but I suspect the more I dig in the more I'll start focusing on the numbers. In the meantime, I am looking to take some Cat classes and diesel classes just for some base knowledge.

But we aren't worried about the rpm's at WOT as much as we are wanting to get that overheating under control at the stated rpms.

Something I glossed right over, how old is the impeller? the starboard side is a PIA so maybe it's been neglected

 

[Thomas Griffith]

Don't have an answer on the impeller yet, but im betting you're on the money.

Added Bonus: the oil analysis came back and they found elevated Copper in both, 154 reading in Port and 178 in starboard. The surveyor says clutch pack wear?

 

[Strecker25]

Don't have an answer on the impeller yet, but im betting you're on the money.

Added Bonus: the oil analysis came back and they found elevated Copper in both, 154 reading in Port and 178 in starboard. The surveyor says clutch pack wear?

in the trans oil? I had elevated copper, lead, and iron but have no idea when they changed the fluid last. When was the last fluid change?

If its been a while I wouldn't sweat it - change the fluid and resample after a while. If its old you're bound to see come copper from normal wear

 

[Thomas Griffith]

Yes from the "gear box" so Trans fluid. Again, I suspect you're on the money with that. I plan to flush out and refresh anything that holds a fluid on that boat.

 

[Strecker25]

Yes from the "gear box" so Trans fluid. Again, I suspect you're on the money with that. I plan to flush out and refresh anything that holds a fluid on that boat.

hoses too! And get ready to pucker when you order the hose clamps