Official Caterpillar3116/3126 Thread

Also Full tabs adds about 50*F on my boat. I started to use less tab and need to get my seat working to sit an inch or two higher.
 
dtfeld said:
Also Full tabs adds about 50*F on my boat. I started to use less tab and need to get my seat working to sit an inch or two higher.
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It didn’t seem to drop egt but I suspect I didn’t wait long enough for things to settle out. I was admittedly nervous about that first ride because it was the first run since having the entire port driveline apart and reinstalled.

next time I’ll take a more methodical approach, but right now there is 3 inches of snow on my boat so that will have to wait

D05F2ECE-831A-49AF-8CCA-4B5B8B0847D4.jpeg
 
Thank you!!!

I've seen the proceedure written up, but could never determine what/where the buffer screw was located!!!

OK. Lets get the idle set up correctly!
 
Strecker25 said:
It didn’t seem to drop egt but I suspect I didn’t wait long enough for things to settle out. I was admittedly nervous about that first ride because it was the first run since having the entire port driveline apart and reinstalled.

next time I’ll take a more methodical approach, but right now there is 3 inches of snow on my boat so that will have to wait

View attachment 103542
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What 3" of snow stops you??!!
 
Interesting discovery today. I was just inspecting things around the ER (how else would you spend a conference call?) and noticed my condensate drains on the aftercoolers. We have hoses that come off them to direct drips away from the engine. I figured it shouldn’t take much to get the one way valve to close so I put a vacuum on it, wouldn’t close. I tapped it with a screwdriver and immediately the valve closed as it should.

now, the Aftercoolers pressure tested normally so I don’t think they’re sticking open all the time or it would be a huge boost leak but I’m wondering if these should be removed and replaced periodically?
 
Strecker25 said:
Interesting discovery today. I was just inspecting things around the ER (how else would you spend a conference call?) and noticed my condensate drains on the aftercoolers. We have hoses that come off them to direct drips away from the engine. I figured it shouldn’t take much to get the one way valve to close so I put a vacuum on it, wouldn’t close. I tapped it with a screwdriver and immediately the valve closed as it should.

now, the Aftercoolers pressure tested normally so I don’t think they’re sticking open all the time or it would be a huge boost leak but I’m wondering if these should be removed and replaced periodically?
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That is an interesting discovery...I dont think I have condensate drains on mine.
 
dtfeld said:
That is an interesting discovery...I dont think I have condensate drains on mine.
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It’s this part. I’m going to start the engines tomorrow and see if it’s closing at idle. It would seem crazy to just have it open until boost kicks in as it’s basically an air filter bypass

https://parts.cat.com/en/catcorp/108-1478
 
Strecker25 said:
Lol, just from going out. I got the new pump and hoses on today though


View attachment 103549
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I'm trying to remember the details but I slid the fuel cooler about an inch forward and rotated that fuel return line fitting so the return hose was on the other side of the oil pressure sender. That completely opened up that area which made changing the impeller super easy.
 
dtfeld said:
Here's the Spec's that CAT publishes for the 2001 350 hp version of the 3126 TA. Yours should be identical.

Boost pressure is listed in Hg guage. Conversion is 2.036 in Hg --> psi Ex @ 2400 RPM boost = 38.1 = 18.7 psi.

@ WOT rpm approx 27 psi and around 1060*F
@ 2400 rpm approx 19 psi and around 810 *F
@2200 rpm approx 13 psi and around 760*F

Ambient air and water temperature, air pressure, relative humidity will have an effect. There is very little boost until you start getting over 2000 rpm.

The only thing I see that is a little out of spec is the EGT @ 2200 rpm, but its not terrible. Go rerun the numbers at 2300 rpm, and 2400 rpm. You might see the EGT come down slightly as you get more boost (air) at those higher rpms relative to fuel. That might be out the window if they changed the fuel delivery.


View attachment 103539
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2300 RPM: ~800*, 18 psi (port) / ~825*/14psi (STBD). 23.5 MPH

2400 RPM: 800*, 20 PSI (port) / 800*, 16 PSI (STBD). 25.2MPH

2150 inches a up to 850* on the starboard side and the port stays at 800*

it seems pretty close to spec, for whatever reason that starboard side makes less boost probably driving up EGT a little bit. I figure since it’s making 2840 WOT it’s not the end of the world and I’ll figure out the low boost eventually. Maybe I’ll pull the turbo next offseason
 
At 800* I think your in good shape, as the real enemy of longevity is excess heat.

as far as boost...Maybe gauge error? What are you using for EGT/boost measurement? Turbocator? Have you swapped boost measurement side to side? Is one line longer than the other? Have you put a good quality gauge on the engine directly?

here video of how to troubleshoot a CAT turbo. This guy is more geared towards trucks/RVs but this generally applies to the marine engines as well. —>
 
dtfeld said:
At 800* I think your in good shape, as the real enemy of longevity is excess heat.

as far as boost...Maybe gauge error? What are you using for EGT/boost measurement? Turbocator? Have you swapped boost measurement side to side? Is one line longer than the other? Have you put a good quality gauge on the engine directly?

here video of how to troubleshoot a CAT turbo. This guy is more geared towards trucks/RVs but this generally applies to the marine engines as well. —>
Click to expand...

i swapped the gauges and it stayed the same, but yea they are turbocators. Before I do anything drastic I’ll test with a better quality gauge.

I might also pop the compressor housing off again and make sure the big oring stayed in place when I reinstalled it.

I’ll rewatch that video later as well, that guy is great ive watched a lot of his stuff
 
Need to bump up my idle RPMs on both engines. They are low, like 600rpm ish.

Side note, my port shift level struggles to maintain its position and therefor RPM under 1300rpm. I push it up a bit and the shift level slides back down a few hundred rpm. Once over 1300-1500 it stays put and is not an issue. Guess I'll address this when adjusting the idle rpms.
 
Correct idle speed is 725-750 rpm's. Adjust at the idle stop screw on the fuel pump near where the throttle control cable terminates. Look at post #183.

You probably have Morse Teleflex controls. There is an idle stop and a friction adjustment under the stainless cover plate on the panel. There should be 2 copies of the manual for your controls in your owners packet, but if you did not get the owners packet with the boat, Teleflex has decent technical info available on their website where you can see which one of several screws adjust what.
 
dtfeld said:
At 800* I think your in good shape, as the real enemy of longevity is excess heat.

as far as boost...Maybe gauge error? What are you using for EGT/boost measurement? Turbocator? Have you swapped boost measurement side to side? Is one line longer than the other? Have you put a good quality gauge on the engine directly?

here video of how to troubleshoot a CAT turbo. This guy is more geared towards trucks/RVs but this generally applies to the marine engines as well. —>
Click to expand...

pulled the compressor housing again this afternoon. Surprisingly easy once you’ve done it before

the big diameter thin o-ring was out of place when I pulled the housing but it could have easily slipped off while I was removing it. I’m going to put a dot or two of permatex aviation to keep it in place.

the other possibly leak source is the clamp bolts, they are tapped right through the housing and I used thread seal but I’m going to also apply aviation sealant to those threads.

The turbo outlet wasn’t lined up to the aftercooler inlet as well as it could be. I doubt that would limit boost but I’ll align it best I can before reinstalling.

Lastly - the wastegate. I was able to exercise it with a handheld bike pump but I’m going to apply 29psi tomorrow which is how the service manual says to test it. Since I’ve never seen 29psi, giving the wastegate seal a little workout could help seat it and seal it back up if that’s where it’s leaking.
 
Racor question: I noticed mine during a change of the filter that the fuel level was below the top of the filter, just slightly. The instructions say to fill it up to the top with clean fuel, which I always do

do you guys find the racors stay full to the top when you change the filter or is a lower level normal?
 
Strecker25 said:
i swapped the gauges and it stayed the same, but yea they are turbocators. Before I do anything drastic I’ll test with a better quality gauge.

I might also pop the compressor housing off again and make sure the big oring stayed in place when I reinstalled it.

I’ll rewatch that video later as well, that guy is great ive watched a lot of his stuff
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Dave on BoatDiesel sure gives good advice...
 
I didn't think CAT turbos are field rebuild able. I was under the impression you had to swap em out. Curious what you find out.

Did you get a gauge on them?

Curious, if the pressure was low prior to removing the aftercoolers? Without black smoke I'm still not convinced you have a problem. I would expect lower power and black smoke from the lower side.
 
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