Looking for 6 CTA mechanic, New Bedford, MA

[Todd]

Just taking a chance here that someone might know an experienced Cummins mechanic to take a look at my Cummins 6 CTA 8.3 mechanical diesel in Mattaposiett, MA (near New Bedford). The local Cummins dealer keeps pushing out, but tells me I shouldn’t use the boat and I am loosing my whole summer. I seem to have internal pressure in the engine that is forcing oil out the exhaust side of the just replaced reman turbo. So, as I understand it I need compression tests and a blowby test. Engine is low hours, but 1998. Everything that bolts on to the engine has been replaced or rebuilt and it gets all the regular maintenance. I would like to find someone who knows the 6 CTA specifically because I have had the yard mechanic go through it and he is pretty good to a point, but doesn’t have the tools or experience on this model to take it any further. Thanks in advance.

Todd

Topic

[Rob Schepis]

How does she do on a cold start?  (No heat on engine or engine room heater and not run for 24+ hours)

[pwrobert]

Exhaust specs

Does your exhaust riser go up any higher thant the section that we see coming out of the turbo?  Doesn’t seem like much clearance above the   turbo exit and we can’t see any pictures of the exhaust tube run.  Turbo replacement could be related if no real nice slope for the raw water/exhaust to flow down.  Maybe mist was issue with previous turbo.   Anything like the riser in  my photo in your system?

[Tony Athens]

Based of this: 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.

I do not think you have anything wrong that requires  a  “diagnoses”  at this point. I think you have “slobbering” going on because of low coolant temps..

1) let’s get your running temp up to 180-ish when cruising and running at harbor speeds– New thermostats?

2) Let remove the exhaust elbow — I want clear pics of the inside from about 12″ away

3) Let’s block sand the turbo casting cast iron face so it’s  smoother

4) Re-install the elbow with new proper hardware and a new graphite gasket —90++% your issue will be gone

 

 

[JimmyK]

You say you have oil coming out the exhaust side of the turbo?  Was it doing that before you replaced the turbo?  Why did you replace the turbo?

Why are they telling you not to use the boat?  Because of an oil drip near the turbo?  Because of this ‘pressure’ coming from the oil fill cap?  Was an actual blowby test done?

It can be hard to nail down the exact source of an oil leak.  If the leak just started with the turbo swap then I’d suspect some of the new work caused it and check the gasket & tightness on both the turbo oil feed & drain connections.  Simple stuff, obviously do it w/engine off.

Always hard over the internet but my sense is you should be out there sipping some cocktails enjoy your boat.

[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

[Tony Athens]

Todd,

 

Other than this “oil drip” that I really do not see well, what are our your other symptoms ?

 

This is what I do see though——Engines look like they run super easy and and I am thinking  that may you spend hours running at very low loads? What is your coolant temp of the engines after all has been running for  a couple of hours? Typical cruise RPM is ??  When you are getting back in your ship after a day of cruising, what are your coolant temps while docking?

I know these engines can “slobber” when running cold for long periods . Your tiny drip  looks just like that ( leaking though the gasket) .  Also. service your Walker Airsep if it has not been done in the last 500 engine hours. 

Before you have a tech turn this into a $5,000 movie, let’s do some other things 1st.

 

Are you a little bit “hands-on”

 

 

[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

[Rob Schepis]

I do not have a referral .  Have you any pics of the oil you are seeing?  And overall pictures of then engine as well?

[Author]

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