Official Caterpillar3116/3126 Thread

Turbos tends to slow down over time due to carbonized oil that forms on the bearings. Depending on whether it's a ball bearing turbo or a journal bearing turbo, that also will impact how fast it accelerates. I have seen some turbos not spin at all when idling. I'm curious to see whether this improves your boost situation. Typically even IF a turbo is tight at ambient temp, they will loosen up when hot exhaust gases and oil flow through the turbo. If this doesn't improve your boost situation, I would look at the following -

1. Boost leaks
2. Differences in your props - is one biting more than the other?
3. Gauge differences (I forget if you swapped them?). Can you reference from a different part of the engine to compare?
4. Restrictions in your HX'er/tube bundle
 
douglee25 said:
Turbos tends to slow down over time due to carbonized oil that forms on the bearings. Depending on whether it's a ball bearing turbo or a journal bearing turbo, that also will impact how fast it accelerates. I have seen some turbos not spin at all when idling. I'm curious to see whether this improves your boost situation. Typically even IF a turbo is tight at ambient temp, they will loosen up when hot exhaust gases and oil flow through the turbo. If this doesn't improve your boost situation, I would look at the following -

1. Boost leaks
2. Differences in your props - is one biting more than the other?
3. Gauge differences (I forget if you swapped them?). Can you reference from a different part of the engine to compare?
4. Restrictions in your HX'er/tube bundle
Click to expand...

thanks, I’ve hit most of what you point out.

1) all new hoses and clamps. Cleaned aftercooler and reinstalled with new gasket.

2)props were worked and prop scanned over the winter to within .1” of pitch of each other

3)swapped gauges and also pressure tested the engine to gauge line to be sure there were no leaks.

4) HX I haven’t investigated. Can you elaborate on this? It’s been freshwater all it’s life but that’s not to say it doesn’t need cleaning. The engine temp stays solid ans does not fluctuate, per the dash gauge
 
Strecker25 said:
thanks, I’ve hit most of what you point out.

1) all new hoses and clamps. Cleaned aftercooler and reinstalled with new gasket.

2)props were worked and prop scanned over the winter to within .1” of pitch of each other

3)swapped gauges and also pressure tested the engine to gauge line to be sure there were no leaks.

4) HX I haven’t investigated. Can you elaborate on this? It’s been freshwater all it’s life but that’s not to say it doesn’t need cleaning. The engine temp stays solid ans does not fluctuate, per the dash gauge
Click to expand...

#4 - HX'er aka aftercooler. Same thing.
 
douglee25 said:
#4 - HX'er aka aftercooler. Same thing.
Click to expand...

check this out, I was mucking around with the old turbo just to get a better idea of how it works and stuck my phone flashlight into the wastegate passage. I am able to see significant light pass through the wastegate into the exhaust passage. Im wondering how much of a wastegate leak it would take to lose boost? I wish I did this on the new one, but I didn’t.

proof will still be in the test run but I like knowing root cause. It’s almost like the seat is eroded? The yellow circle is where light comes through

9BB33780-0227-4D5A-AC48-A5BB291E1E8B.jpeg
 
Yep, looks like a boost leak to me. Should for sure be 100% closed.

See if that's carbon at the bottom of the wastegate that will chip off. Will the wastegate seal then?


Edit - also check the bushing that the wastegate shaft rotates in. Those bushings have a tendency to wear and then the wastegate will also not seal either. In fact some times you can hear wastegate flutter when this bushing fails.
 
8C534B5B-3074-4257-91D7-B804B4F60A21.jpeg
douglee25 said:
Yep, looks like a boost leak to me. Should for sure be 100% closed.

See if that's carbon at the bottom of the wastegate that will chip off. Will the wastegate seal then?


Edit - also check the bushing that the wastegate shaft rotates in. Those bushings have a tendency to wear and then the wastegate will also not seal either. In fact some times you can hear wastegate flutter when this bushing fails.
Click to expand...

this thing is f’ed up for sure. I just put 40psi on it and the wastegate didn’t move! Manual says 29psi max for testing should fully actuate it.

so, I put a set of vice grips and moved the actuator open manually. It’s so corroded that it stuck open and wont return. I have to figure water or moisture got into the turbo somehow for it to seize up but maybe it’s just age

by the way - this is just my core return so that’s why I’m messing with it before returning it.
 
Maybe you should reward yourself for all your hard work with a set of new wheels!
 
dtfeld said:
Maybe you should reward yourself for all your hard work with a set of new wheels!
Click to expand...

lol... I'll be so sad if I have to get them repitched again but we're at 21.5" and a lot of other folks reported similar change to hit 2850. I suppose I'd rather be a little underpropped than over
 
The results are in and they’re wonderful.

Boost/EGT at 2230 is now 18psi and about 675*. Port side is 15/16psi and around 800”*, looks like I’ll be inspecting that turbo too and possibly replacing it too!

It’s quieter and noticeably smoother. I feel like it’s a new boat

https://youtube.com/shorts/PgmhNJqhJbA?feature=share
 
Last edited:
Strecker25 said:
LOL that’s a fantastic idea.

remind me, did you re-pitch your boat?
Click to expand...

I have not. I need to look at the EGT at different trim settings, but generally speaking, my EGT are below 800, so I'm not sure it's necessary.
 
Here’s my other side. It runs about 2psi less at the same rpm as the new turbo and about 100* higher egt but it’s still in CAT spec. As much as I’d love to replace it now im not sure I want to spend another 3k when I don’t really have a problem. Maybe this off-season, still contemplating. It’s clearly better than the other side which was badly eroded
46AC38C9-A2AF-4902-AF34-620B3560B0C4.png
 
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