[Todd]

Thank you Tony,

Yes the photo on the oil drip is terrible, I will try to get another.

I am hands on for maintenance, but not a mechanic in any way. I am ok with getting a mechanic involved as needed since I want it diagnosed and remediated correctly.

The motor is on a 1998 42 ft downeaster pleasure boat. I bought it from a guy who used it for cocktails cruises and he bought it from a similar party. So low hours maybe 1,000 and probably mostly low speed.

I have really not been able to use it yet since we have been servicing all the bolt ons, replacing 25 year old hoses, clamps, new motor mounts, etc. Also prop and shaft serviced.

I have one engine and as such I want it to be as reliable as possible and I try to get everything set up “Seaboard Style”.

The engine seemed to run fine when I bought it, except for some vibration that was fixed by the above mentioned service, and I had a Cummins mechanic do a pre-purchase survey. We have oil tests. All normal

When we put the boat in this spring after replacing the gear and servicing the HX and AC we started noticing the problems described here.

There is some black smoke, mostly if we gun it up from idle. We had the low rpm governor retard issue, so rebuilt the injector pump and low idle now seems fine. It is slightly rough in the 500-700 range but that seems normal on Cummins. On the last sea trial while running at 1600ish rpms, the rpms would randomly fluctuate by 50-100rpm every minute or so. A little fuel in the exhaust as well at idle ( at least it is shiny so I assume fuel).

It does run up to 2700 WOT (I had it propped as you suggest). Coolant temp is fine there. I only run it WOT for about 8 minutes to test. I prefer to cruise at 1600-2000 for fuel economy. I still get 8-12 knots of boat speed. 17 at WOT

The operating temp does get up to 180 which seems normal to me. Back at the dock after a run I think it dropped back to the area of 135-140F at idle, but I don’t recall the exact reading.

Another small issue I have is the SMX digital engine display keeps tell me the gear oil pressure is low. Cory sent me a software patch that did not change anything. The gear is a brand new TwinDisc and we checked the pressure at the gear and it is fine. I guess I need to get a new sender next, but I do not know the model to get from you.

We have also checked the fuel pressure after the racors and before the injector pump and found that to be in spec. Racor vacuum gauge shows no deflection all filters are new.

They did manage to get to the boat yesterday and just told me a compression test resulted in all the cylinders being within 1 psi of each other at about 425PSI which seems promising but a higher number than I would have thought?

Apparently, when running the engine there is pressure coming from the oil fill cap if removed and the oil dipstick. Can anything besides blowby from internal wear cause that?

The Walker has been cleaned by me, I have used them on previous Cummins engines. I also replaced the mini filter on what is the breather I guess. Yard mechanic doesn’t like Walker and wants to try a paper filter with a breather to ensure there is no back pressure from the internals of the Walker.

I am going to head over now to see if they are back on it and what their plan is and try to get more info.

Thank you and everyone else here for all the great assistance and advice…

Todd

[Todd]

Thanks Rob, I think I have found the mechanic, now to get him scheduled in.

I have attached engine photos here.These photos are from Just just before we replaced the turbo and fuel pump with remans. all hose replaced in last 12 months, rebuilt injectors last month, service HX in April, new AC core in April, new fuel cooler, recent starter…

The oil is leaking out right at the metal gasket on the exhaust side of the turbo. It is not leaking exhaust there. The photo of the oil leak is poor, but you can see oil.

Todd

[Todd]

1997 6 CTA 8.3 430HP gagging around 700-850 rpms. Just jumping in to get copied on replies. Will post any findings. Back on the boat tomorrow. All fuel filters new. THX

[Todd]

Hi Mike,

Thank you, I appreciate your experienced view on this.

Todd

[Todd]

I have a single 6 CTA. Usually cruise at about 2000-2100 since the flow scans show a much better fuel burn vs. the little add’l speed I get higher up. Then I run it al the way up for about ten minutes at the end of the day. I did the same as you: dialed in the prop to get 2700 per Tony’s recommendation on this site. Not a lot of hours on it since then, but no complaints so far.

[Todd]

Thanks Rob,

So just to read this back since I am not familiar with it and I want to ensure I get the instructions right to the machine shop:  ( I have searched and not been able to find where Tony discusses this)

There is about 30 thousandths extra length in the AC body.

Take in down 10-15 thousandths to get a smooth surface.

I’ll then get new seals reassemble and pressure test. Then off to the races.

It looks like I can get a new core locally, so I will start with that. I am calling the Seaboard parts desk to get on the list for a new seaboard style housing.  Although looking at this one, it is pitted inside from seawater leakage, but does not seem to have a performance or structural impact? Maybe it has life left after machining the sealing surfaces? I added some pix here. Not experienced with this issue so maybe a bad idea to try to keep it for a while?

 

[Todd]

Rob- see two photos here

[Todd]

Yes, Dougin, in MA, and thanks will check into a bigger oring

[Todd]

Hi Rob, I am trying to get some photos today.

They did a soap test on the bundle produced a huge amount of bubbles from the middle area so did not seem fixable.

[Todd]

Sounds like the smart move. Do you have a spare impeller?

[Todd]

+1 for John’s recommendation of get new.

At a minimum clean as Tony suggests AND take it to an engine shop to get it pressure tested to ensure no pinholes.

[Todd]

Thank you John and everyone.

I have picked up some of the Power Service and will add that today.

John Hobby, I change the primary filters regularly, but is there something about this additive that makes that even more important?  (Also, I am not far from you in Buzzards Bay)

 

Thanks again!

[Todd]

Great, thank you for the replies here.

[Todd]

Thank you Tony. Will give that a try. Just concerned about reliability more than anything.

[Todd]

Thanks Neto, I imagine the clamps and also the hoses…

[Todd]

Thank you Rob,

all good points. I think I may also ask for the disassembly and Seaboard style reassembly of the aftercooler since it is a big $ part, probably an inspection of the HX as well. I am also keen to get the freshwater rinse attachment for the Groco.

Is the Seaboard Envirovent better than the Walker airsep in the photos? They appear to me to be of very similar design?

Thanks again,

Todd

[Todd]

Here are the fluid reports and add’l pix, ran out of attachment space on the last post…

 

Thanks,

Todd

m 617 429-4852

[Todd]

Thank you Tony, I will order the torsional coupling try that and change from ATF to 15w-40, one less fluid to keep on the boat!

[Todd]

Thanks Firehoser, I have the Sherwood pump, but the SMX brand impellers I get from SBMAR, so likely the same/similar to what you have. I found a Sherwood flyer that says change annually for light pleasure use or every six months for pleasure use at high RPM or silty water, but no “hours” recommedation. We seem to fall somewhere in the middle of those.

On my engine it is actually far easier to just change the pump and then change the impeller at my comfort and leisure, so I bought an extra pump that also makes a good backup…

Cheers,

Todd

[Todd]

Hi Tony,

Pump and impeller are new as mentioned below. So, with my current use pattern I am trying to better understand a reasonable replacement cycle for the impeller.

Thanks!

Todd

[Author]

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