Still have 3116 issues

Avalon

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I've got a 3116 in a Nauset 36, finished by Shannon. 3116 was rebuilt but has never been quite right. Engine started life as a 205hp and was remanned to 300hp. Starts fine but doesn't get up to 2800+ rpm. Starts right up but hunts at idle when warm. Have had the rack run multiple times by "authorized Cat" mechanics. Have replaced the governor, Racor filter, oil of course. Prop has had pitch taken out twice. Nauset confirmed that the original 300hp 3116 turning a 22x18 wheel on a 1.5 reduction was the original configuration. Prop is now 22x15. Plan on taking it to another "authorized Cat" mechanic and have them check everything from fuel tank to exhaust. What all do I want to make sure they do to get this engine running right?
 
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digs

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Very likely starving for fuel. That motor will run with less power and not stall out like most once fuel supply is compromised . turbo is sensitive to water intrusion in those also ? Easy to hang em up . Eliminate any possibility of fuel restrictions . There is inlet screens on most to look at also . Take your time and get fuel supply unlimited first .
 

digs

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Make sure the intake cooler is flowing clear as well . Common to soot up without the proper motor oil from cat developed for this application .
 

PatriciaLynn

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Take the fuel return and disconnect it. Run some clear silicon hose into a bucket. Look for clear, clean diesel coming back with no bubbles while the engine idles. If you have black or dark diesel and/or bubbles, then you have comprimised injector cups. CAT can ream these cups with a special tool ( I have done it, not hard) then you have to reset the rack. If they are completely gonzo, you have to use a different tool to remove the cup and then press a fresh one in. Good luck!
 

F/V KRISTA MARIE

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Was the fuel rack synchronization, injector timing and full fuel setting ever completed?
 

WoundUpMarine

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Avalon

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Was the fuel rack synchronization, injector timing and full fuel setting ever completed?
Yes, several times but as there was no ID/Spec plate on the engine, it's been a bit of a crap shoot getting it right. Even the Cat techs were "challenged" to get it set correctly, which it may still not be.
 

Avalon

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The fuel inlet screen has shut my buddy's 3116 down a few times, but was completely resolved when we put a racor in before the fuel pump(this is on a 10 wheel dump truck). If you don't want to wait for Cat, do what @PatriciaLynn says and check the integrity of your fuel injector cups, the 3116's are known for having this problem.
I've got new a 30 micron Racor filters installed. The original was 2 micron and got clogged fairly quickly. That helped. Also have a pressure gauge on the racor so I can tell when it needs to be changed. I'm beginning to think that the problem is with the injectors/cups as PatriciaLynn has suggested.
 
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Avalon

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Make sure the intake cooler is flowing clear as well . Common to soot up without the proper motor oil from cat developed for this application .n
Pulled the aftercooler and had it hydrosonic tanked @ 150 hours just to confirm that it was squeaky clean. Now we know it is for sure!
 

Avalon

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Take the fuel return and disconnect it. Run some clear silicon hose into a bucket. Look for clear, clean diesel coming back with no bubbles while the engine idles. If you have black or dark diesel and/or bubbles, then you have compromised injector cups. CAT can ream these cups with a special tool ( I have done it, not hard) then you have to reset the rack. If they are completely gonzo, you have to use a different tool to remove the cup and then press a fresh one in. Good luck!
Thanks for the suggestion. I'm beginning to think that the problem lies with the injectors and/or cups. After that is confirmed/corrected, getting the injector timing and fuel settings right will be the next step.
 

Avalon

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Very likely starving for fuel. That motor will run with less power and not stall out like most once fuel supply is compromised . turbo is sensitive to water intrusion in those also ? Easy to hang em up . Eliminate any possibility of fuel restrictions . There is inlet screens on most to look at also . Take your time and get fuel supply unlimited first .
Forgot to mention that the Turbo oil line was clogged so it was pulled, blue printed and rebuilt at about 100 hours. It "sounds" like it is spinning up pretty well but want to get a gauge on it to check the boost.
 

GypsyJon

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I've got a 3116 in a Nauset 36, finished by Shannon. 3116 was rebuilt but has never been quite right. Engine started life as a 205hp and was remanned to 300hp. Starts fine but doesn't get up to 2800+ rpm. Starts right up but hunts at idle when warm. Have had the rack run multiple times by "authorized Cat" mechanics. Have replaced the governor, Racor filter, oil of course. Prop has had pitch taken out twice. Nauset confirmed that the original 300hp 3116 turning a 22x18 wheel on a 1.5 reduction was the original configuration. Prop is now 22x15. Plan on taking it to another "authorized Cat" mechanic and have them check everything from fuel tank to exhaust. What all do I want to make sure they do to get this engine running right?
I had the same problem with a Yanmar 315 hp engine. Finally has the fuel polished and tanks cleaned. Voila! Problem solved.
 

Avalon

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I had the same problem with a Yanmar 315 hp engine. Finally has the fuel polished and tanks cleaned. Voila! Problem solved.
Thanks for the suggestion but the tanks are new.
 

tunafishhkg

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Just in case, I had one that the internal check valves, two of them, in the injector pump, are wrong and do not seat correctly causing similar problems. The correct part number is wrong check valve. Owner Had injector pump rebuilt yr later and even after telling them about this issue, had to be sent back after rebuild.
 

eyecatcher

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If your using the 1R-0751 standard engine filter, it is a 2 micron, A 30 primary Racor will last a while before getting plugged but the last chance CAT engine filter will clog easily if your fuel quality is poor. I always ran a 10 micron Racor on my Cat's YMMV. The Cat injectors are not cheap I would recommend the CAT filter, it is the best. If you go with a Napa or other filter they are usually 10 micron. If it was upgraded to from 205 to 300hp, do you have 1/2" inlet and 1/2" return lines and a racor 900 series filter? You should also be running straight sae 30 oil in it not multi grade.

As far as your issue it does sound like it is fuel related. Assuming it has a 300hp governor, cam, turbo, injectors, can it it 3150 RPM with bare idle no load? There are many things to look at. You definitely don't want any air in the fuel it will cause your issue. Checking the return line as suggest is a good place to start. You could try to just run it out of a bucket of fuel source and return to the bucket to eliminate isolate any air from possibly your pickup, fuel line, valves, racor etc.. The cat fuel is similar to a common fuel delivery. There is a fuel gallery in the head that is pressurized that each injector feeds off of. If one of the injectors is damaged or not well seated you can get compression gasses past the cups and o-ring seals into the fuel gallery causing poor performance idle and throughout. It may be worth knowing what kind of fuel pressure your making at the filter, should be 20psi min to 60psi.

Crap shoot sounds crazy your engine will never be right.. You would probably want to research from the builder that remanned it or get a service manual for a 300hp to determine what the performance spec is for fuel rack timing, and injector height is from who did the rebuild. It is very precise and specific. Off the top of my head it is probably something like 3.4mm and 62-65mm The techs usually don't have the info on hand unless they work on them often. Is there a CAT dealer near you? Get the engine put back on spec, special tools are required. Once the valves and rack is good, it shouldn't need to be messed with, just checked every x amount of hours or so unless your replacing something.Once fuel is good you can check to make sure your making the proper amount of boost at wot if I recall it should be around 25-28psi
 

Avalon

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If your using the 1R-0751 standard engine filter, it is a 2 micron, A 30 primary Racor will last a while before getting plugged but the last chance CAT engine filter will clog easily if your fuel quality is poor. I always ran a 10 micron Racor on my Cat's YMMV. The Cat injectors are not cheap I would recommend the CAT filter, it is the best. If you go with a Napa or other filter they are usually 10 micron. If it was upgraded to from 205 to 300hp, do you have 1/2" inlet and 1/2" return lines and a racor 900 series filter? You should also be running straight sae 30 oil in it not multi grade.

As far as your issue it does sound like it is fuel related. Assuming it has a 300hp governor, cam, turbo, injectors, can it it 3150 RPM with bare idle no load? There are many things to look at. You definitely don't want any air in the fuel it will cause your issue. Checking the return line as suggest is a good place to start. You could try to just run it out of a bucket of fuel source and return to the bucket to eliminate isolate any air from possibly your pickup, fuel line, valves, racor etc.. The cat fuel is similar to a common fuel delivery. There is a fuel gallery in the head that is pressurized that each injector feeds off of. If one of the injectors is damaged or not well seated you can get compression gasses past the cups and o-ring seals into the fuel gallery causing poor performance idle and throughout. It may be worth knowing what kind of fuel pressure your making at the filter, should be 20psi min to 60psi.

Crap shoot sounds crazy your engine will never be right.. You would probably want to research from the builder that remanned it or get a service manual for a 300hp to determine what the performance spec is for fuel rack timing, and injector height is from who did the rebuild. It is very precise and specific. Off the top of my head it is probably something like 3.4mm and 62-65mm The techs usually don't have the info on hand unless they work on them often. Is there a CAT dealer near you? Get the engine put back on spec, special tools are required. Once the valves and rack is good, it shouldn't need to be messed with, just checked every x amount of hours or so unless your replacing something. Once fuel is good you can check to make sure your making the proper amount of boost at wot if I recall it should be around 25-28psi
Thanks, Eyecatcher! Really appreciate your insight and suggestions. I have the 2 micron Cat Fuel Filter. It now has ~230 hours on it. How often (hours) should that be changed? The fuel tanks and Racor are new. Cat techs installed a new governor @ 150 hours and ran the rack. Have confirmed that the engine has the correct injectors. I only use Cat SAE 30 oil. The engine will easily run up to 3150 rpm with no load. Have confirmed that with a photo tach. I will have to confirm the fuel lines but I believe they are 1/2". I run through ~600 gal. of fuel/year so I think that is pretty clean.
The builder was not an authorized Cat shop and is proud of the fact that he doesn't use all OEM parts in his builds. He has not been able or willing to provide me with the timing specs he used and I'm not sure that he even used the Cat timing block. Ugh! #5 Injector has always been problematic so after everything else has been checked and double checked, that is probably the place to start. Injectors may be expensive but they are cheaper than a new engine. :)
 

Avalon

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Just in case, I had one that the internal check valves, two of them, in the injector pump, are wrong and do not seat correctly causing similar problems. The correct part number is wrong check valve. Owner Had injector pump rebuilt yr later and even after telling them about this issue, had to be sent back after rebuild.
Very interesting Tunafishhkg. Will definitely have that checked out. Thanks!
 

eyecatcher

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Thanks, Eyecatcher! Really appreciate your insight and suggestions. I have the 2 micron Cat Fuel Filter. It now has ~230 hours on it. How often (hours) should that be changed? The fuel tanks and Racor are new. Cat techs installed a new governor @ 150 hours and ran the rack. Have confirmed that the engine has the correct injectors. I only use Cat SAE 30 oil. The engine will easily run up to 3150 rpm with no load. Have confirmed that with a photo tach. I will have to confirm the fuel lines but I believe they are 1/2". I run through ~600 gal. of fuel/year so I think that is pretty clean.
The builder was not an authorized Cat shop and is proud of the fact that he doesn't use all OEM parts in his builds. He has not been able or willing to provide me with the timing specs he used and I'm not sure that he even used the Cat timing block. Ugh! #5 Injector has always been problematic so after everything else has been checked and double checked, that is probably the place to start. Injectors may be expensive but they are cheaper than a new engine. :)
I would recommend you change the on engine fuel filter at the beginning of your season at least. A timing block should have been used. CAT has a special tool kit to do this procedure properly, but he may have just synced the rack up with #1 skipping that step. IDK what is going on with your #5 injector (companion cyl is #2), but one bad one will cause the engine to run rough or kill out cylinder #6 and have low power since they all share the common fuel gallery in the head. Don't go changing any other parts until you get that worked out. Would be beneficial to temporarily use a sight glass on your inlet and outlet lines or run it out of a bucket at the dock. A smart tech will know how troubleshoot the cylinders with the valve cover off to listen to the engine while idle. Good Luck.
 

Avalon

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Thanks, again! Really appreciate your (and everyone's) input. Will order and install a new on-engine 2 micron fuel filter and will plan on changing that every year when I do the oil. Getting #5 sorted out is my top priority at this point. I suspect that is the route of all my problems.
 
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