White smoke, black soot

[Justin]

Heres’ what going on with my 6CTA 8.3s, CPL 2172 with about 1280 hours. I am hoping to get some answers and instructions on what to do. I posted my questions on another forum, but no specific answers there yet.

My engines have always been rather smokey since I´ve owned the boat (for just over two years now). As of late, however, they have gotten ridiculously smokey at startup. When I say smokey, I mean my dock neighbors flee, wildlife disperses, and Google Earth can spot it on satellites. The smoke is white with maybe a tiny bit of gray. The water temperature is 60 degrees. The starboard engine seems a little worse. I am getting voltmeter fluctuation, suggesting the air heaters are engaging. At startup, the stb has begun to idle roughly, with fluctuating RPMs enough to make the synchronizer gauge show it clearly. When the engines are hot, the there is much less smoke, but still probably more than any other boat in the marina. I recently completed a 962 NM trip from the Great Lakes to the Mid Atlantic with 1209 gallons of diesel burned. On the trip, I had to scrub the entire transom and cockpit daily because it was getting covered in black soot. On the trip I noticed that the stb was consuming a bit more fuel, maybe 5-8% more. It was after this trip that the amount of smoke from both engines got really bad. It also it not quite making the speed it used to, with maybe a knot or so less for given RPM. It could also be the way the boat is loaded, though, which is very heavy. I am pretty sure I can´t blame it on a bad batch of fuel because I went through several tanks on my trip. Maintenance so far has been new oil filters with changes, changes of racors, fuel filters, coolant filters, new coolant, zincs, transmission fluid, impellers, and also after cooler service according to Tony’s excellent online instructions. and Any ideas what is going on? I would appreciate your ideas and suggestions. Thanks,

Justin

 

 

Topic

[Rob Schepis]

Well that is a positive sign that you did not have an rpm/performance drop, you may come out without piston/ring/bore damage.

You need to get an experienced tech down there to pinpoint that oil leak and a full diagnosis before pulling anything apart.

Too many variable such as travel time, labor rates, engine room access, etc and too many unknowns to start to ballparking numbers.  Plus if the head comes off you’ll be doing further inspections of all.

[Justin]

Rob, thanks for the info and advice. I became aware of the overheat not by any power loss or performance change. I was looking at the temp gauge frequently as usual, and on my next check about 2 minutes or less later I saw the overheat. It came up very fast, but short because I shut it down. I hope nothing is cracked for sure. There is an oil weep as a result of the overheat, so I imagine that is coming from the head gasket. I think the lost of coolant was from expansion blow out. I checked the oil for signs, and it was fine. I will check the cap for any signs today. By the way, if I do need a head gasket, can you give me any ballpark figure of what that should cost? I don’t have the time for that right now and it’s not something I have done before–probably beyond my reach.

[Rob Schepis]

Following an overheat..

There’s always a chance you could have a cracked head, ex manifold, turbo, blown head gasket, etc.  You didn’t mention if you lost coolant?  If so, a little like expansion blow out or a lot?  Check the underside of the oil fill cap and compare the two engines – is it milky compared to the other engine? Have you taken it for a run yet?  Keep an eye on temp and oil pressure and monitor the coolant level closely. You can also compare blowby between the two engines. How did you first become aware of the overheat?  An alarm?  loss of rpm? or you just happened to notice the gauge?

[Justin]

Yes Rob, it was a coolant-side issue and easy to resolve. I think the oil weeped out of the head gasket, but I am not completely sure, as I can’t really see there. The paint for the most part does not look more cooked than before, with maybe the exception of at the exhaust manifold/head interface. I did find a piece of balled up paper towel I forgot on top of the engine that was singed, though. The engine starts fine, idles smoothly, and sounds the same. Maybe more smoke? Not sure, as I need to run it up to temp and see what happens then. What are the potential hot spots in terms of possible damage? What do you think I should look for in terms of damage? Clues in performance that could tell me something is wrong?

[Rob Schepis]

<p>Any further diagnosis since you posted this?  Is that a head gasket leak?  Did the overheat cook the paint?  High load overheats are seldom without damage, especially if it’s due to a coolant side issue, not a raw water side issue since a loss of raw water situation still has coolant flowing.  Did you lose any coolant?  Could the overheat have been caused by air trapped in the coolant?  No alarm went off?</p>

[Justin]

Updates good and also despair ;(

<p>Here are some updates to what I have done so far with the good and the bad. In a reply to this thread Tony suggested 5 updates. I have put in new 5-hole injectors, new Seaboard 180 degree thermostats, repitched prop (reaching 2800-a bit of an overshoot), and adjusted the valve lashes. The only thing I did not get to yet is the pan heaters. I’ll order those from sbmar next week. At first I did not see much improvement, with the exception that the engines had a different click/clack profile, and all around seemed better in that regard. I found that most of the valves that needed adjustment on each engine were too close and had to be let up a bit. I was surprised, thinking that time and wear would open up the lashes. I am curious to know what effect too close of a lash would have on performance. I did find out that I had bad fuel after an experiment. I transferred all the fuel to one tank and filled the other with fresh fuel. After getting underway at 1200 rpm smoking up the river, I switched the engines to the new fuel and presto! Very little white smoke. I switched back again, and within a few minutes the smoke was back. So the good news is that the smoke is taken care of, but I did go through a lot of bother that may not have been necessary. On the other hand I am still very glad I did those things, as I learned a lot, and I also have the peace of mind that I have fresh injectors, hotter thermostats, and good valve clearances.</p>
<p>So now for the possible nightmare….? I was testing the boat again today in the ICW and finally starting to feel good and satisfied with my efforts and expense. The temp gauges were reading somewhere around 190 on plane. After obsessively checking the temp gauge every few seconds I started to get used to the new normal. I decided to run a little harder (2500) to burn off whatever might be left in the exhaust manifold, hoping for a cleaner cold start up next time.  Then my STB engine overheated. The gauge tops out at 250 and it was pegged. It could not have been for more than 2 minutes. Upon opening the engine room hatch a cloud of coolant steam filled the salon and I couldn’t see anything. There is a oil leak (see pic), with about 1 cup lost. I would like to know first, what damage have been done, and second, what may be the culprit. When the engine cooled down, I restarted it. It seemed normal, maybe a bit noisier (could be my paranoia). Checked the impeller (changed 3 weeks ago) and it was perfect. Water flowing out of the exhaust.</p>
<p>Could this be related to the new thermostats? Today was the third or forth time I ran the boat with them in. At each time, the temp gauge on the STB was slightly warmer than the port side. It looked like ten degrees or so, small enough that I thought I would change the senders and see. Another clue is that the STB has been warming up to full temp much faster than the other side since the work I did.</p>

[Rob Schepis]

Yeah, get him out there without delay, as you know a poorly seated prop can cause shaft fracture.  I wonder if the props were ever lapped to the shafts..

So you picked up better that 150rpms, she must really feel better once you get going beyond hull speed..

[Justin]

Rob, thanks for pointing out where the thermostats are.

 

Yes, I am getting 2710 and 2705 turns at WOT no problem. As far as the vibration, I was concerned that the diver was using a wood block on the props instead of a pipe wrench like I always use. I hope he didn’t deflect a blade. He could have keyed up one or both as well. I need to get him back out and check.

[Rob Schepis]

RPMS / Props / Vibration

Good to see you got the tach’s sorted out.  Does she make the 2,700 easy?

So the vibration was not there before the prop work?  but is there after the prop work?

If that’s the case my thoughts are:

1) prop shop work faulty (unlikely)

2) a blade was tweaked when the prop was installed, such as with chocking/blocking it at the tip of the blade against the underside of the hull when tightening the nuts.  if the prop is not chocked down near the hub a blade could be tweaked out of true

and/or

3) the prop/key is not seated and installed properly

[Rob Schepis]

Thermostats

See attached

[Justin]

updates

In the first step toward the advice from Tony, Rob, et al., I have had my props redone to make sure I am getting turns into the 2700s. I am now getting 2710 and 2705 with photo tachometer. It’s a little shy of the goal, but I am hoping it’s close enough to satisfy Tony. My helm tachs were way off and I have calibrated them. I remember the previous owner saying he sent them in for rebuild. I found stickers on the back of them with the date of the rebuild. Clearly his mechanic did nothing to set them up on reinstall. So now I am getting pretty close readings across the range and an accurate sync gauge now.

My next step will be to get the 180 degree thermostat kits and put them in. I saw on this site that the kit contains two thermostats. So the 6CTAs have two each? Also, I am not sure where they actually are on these engines. If someone could let me know, I’d appreciate it.

At the same time, I need to tackle pulling my injectors out to rebuild them to 5 hole injectors. Then comes valve adjustment. Looking at my engines, it looks like pulling the injectors for 3,4,5 cylinders might be a pain. Would it be a good idea to do valves and injectors at the same time since I will have the valve cover off?

Now I am having a different problem with props, however. I get a notable vibration on plane that was not there before. This is frustrating to say the least. While the wheels were off, I was able to run the boat in gear to test for vibrations that way while setting my tachs. Nothing-no vibrations and just like in neutral across the range. So it has to be the props. I wonder if the diver have keyed them up. I hope it is that simple. Otherwise I have no clue. Of course the prop shop wants to recommend a new set…

 

Justin

[Rob Schepis]

Prop Cup

Agreed on “some” cupping.  Cup will reduce cavitation and increase efficiency but I say “some” because there is a threshold where adding cup no longer provides performance gain and all it does is provide more load.

[Justin]

Thanks for the info, Rob. I will clean them and see what happens. I looked at my tachs and there is no setting for 127 teeth. There’s something like 107 and 138. So maybe the problem is therein.

So the wheels went to the prop guy today. I told him what numbers I was getting and what I am shooting for. He was asking about the performance characteristics generally, and thought I would benefit with some cupping on the props. Naturally, he’d have to take even more pitch out to compensate for that. He thought I would have to use less tab with some cupping. I have no complaints about the hole shot, just that usually I deflect the tabs 3/4 to get the most speed per RPM. With no tab I get a big speed penalty and a 10 degree or so bow attitude. While that’s a drier ride, I don’t want to lug the engines that way. So is cupping advisable here? My last prop guy was pretty against cupping so I am not sure. I have to give him my plan tomorrow so for any expertise on the matter I would be grateful.

[Rob Schepis]

Tach's Troubleshooting

You can remove the magnetic pickup sensors for cleaning.  When you reinstall lube the threads and install until they bottom out and then back out a half turn and them lock them there.  And then unplug and clean and spray all connections starting at the sensors and work your way up the harness to the tachs.  127 tooth flywheel, see link below.

I would get the tachs sorted out before using the boat more than necessary unless your real good with syncing by ear because running with varied rpms means one engine is always working harder than it should.

http://www.sbmar.com/articles/beede-tach-settings-cummins-flywheel-tooth-count/

[Justin]

I was just on the phone with a guy from Aetna last week getting advice on my tach situation. He was very helpful. But I am not sure where the problem lies, whether the senders are bad, the wiring has noise, or my tachometers are bad, or if more than one problem exists. Not sure how to troubleshoot. How many teeth on the flywheel of the 8.6?

On the other hand, now that I have data, I can run in the meantime at proper RPM by the numbers I have now, instead of the helm tachs.

But now that I know I get better than 2650 WOT as is, and I want to get to 2725-2750, do I need to take off an entire 3″? Will I get another 100 RPM with one inch off?

 

[Rob Schepis]

For Starters

IMO the first thing is to concentrate your efforts on getting a good set of accurate tachs installed, Aetna’s maybe, and just run her “light” in the meanwhile until you get the rpm’s sorted out.

After the tachs are sorted out….fast forward…your a couple thousand pounds light on fuel so Tony’s original 200rpm short and 3″pitch removal comments seem pretty darn close….Fuel her up, invite a bunch of fat guys and go for another ride with accurate tachs..

[Justin]

I do not have a mechanical synchronizer. All I have is the standard gauge. I ignored that today for the sake of the test and simply throttled each engine to the helm tach as a standard.

 

[Rob Schepis]

Synchro's ???

Are you running synchronizers?

Your no load rpm is fine.

[Justin]

New Data, opinions?

I got RPM data today and ran the boat over the range. I found out my helm tachs are all over the place. I will post my data sheet for opinions because this may change things. How much pitch should I take off the wheels now? Do my engines pass the no-load test?

 

[Justin]

I have a diver coming out next week to pull my wheels for a repitch. This weekend I will get accurate RPM numbers as well. In a few weeks when I have some time off I will pull my injectors and have them rebuilt to the five-hole version. I will change the thermostats as well. Is there a tutorial or set of instructions somewhere for changing out injectors? Thanks Rob for the link in your previous post.

[Author]

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