[Roger bing]

Beautiful…. 905F.  I am assuming this is the max.  

[Roger bing]

just to add, both motors were producing low boost 8 & 9 lbs.  Coolant temps were 165 and 170.  

[Roger bing]

Rob, good call on that reference electrode. That thing is definitely somthing handy to have. I tested the boats hull potential and it is actually at the high end of the “protected” region. Turns out shore lead may be problem. Hull potential dropped from 1054mv to 930 mv when I plugged in. The book says anything 100mv or over will eat electrodes. Before notifying marina I tried to repeat the test and sure enough it came in at 1054 mv (which would be perfect). I jiggled the shore connection at the boat a bit and it jumped all over and settled down at 930mv. Going to retest tomorrow with a friends cord but it definitely looked promising. Also will leave boat unplugged for few days to see if zinc pieces stop exiting motor during initial startup.

[Roger bing]

Went down today… disconnected ground from battery… measured 1.8 miliamps of current with battery switches off. started disconnecting wire by wire.. got to the point where all sources were disconnected ( pos to starter, alt output, shorepower removed, etc.) There was not a source of power feeding this motor left connected. Yet it still read 1.8 ma between the coolant and battery ground.. only way I could get current to stop was to disconnect positive from battery as well.. other motor came in at 1.3 ma. I’m stumped.. only thing left is to move boat and retest to eliminate slip/marina as culprit..

Before I left I noticed what I posted in pics.. paint on exp tank was gone where coolant overflowed after filling.. other motors paint is still there. I guess I should test the ph? It’s brand new stuff I just changed upon installing new exchanger..

[Roger bing]

Hi rob thanks for the reply… I haven’t looked at running gear yet since boats only been in water for a month and waters way too cold to swim lol. I’ve already thought about the marina. I recently moved to bay shore and am no longer in Freeport..I never noticed uneven zinc wear between motors in Freeport. problem is the marina I’m in is mainly outboards… I’m literally the only inboard on my dock and I don’t think they worry about electrolysis as they pull motors up. Also I appear to be only boat that plugs in on my dock. I would imagine if the dock was “hot I would see it between both motors no?

After thinking last night I am wondering if my block heater may be an issue.. I think that is the side it does not work. I do not leave it on but perhaps there may be stray current coming in through the neutral …i will remove plug. And see what happens after testing for current.

[Roger bing]

Thanks for the feedback. Im not happy with the condition of the 3 week old pencil zinc in exchanger though. Somthings up. I will take look at water on start again and post once i know more.

[Roger bing]

After starting the engine I run to the back of the boat from the bridge. You can see the cloud that has dispersed into the water about a foot and a half from the transom. I look at the other exhaust and its not there. In it you can see little pebble like pieces that appear shiny. Unfortunately, the water in my marina is brown so its hard to see more to tell you exactly. I am going to pull sw feed to elbow off prior to startup and shoot it into bucket in a few days. Hopefully it will tell me more as to what exactly is going on.

[Roger bing]

I serviced aftercoolers in the fall (early Dec.) and pressure tested. All is good. The aftercoolers are not the issue here. The engine is running fine no variation in top end RPM, stack temps, etc. I was simply noting the excessive, premature zinc wear when I checked the pencils after having the heat exchanger issue.

So its been a few weeks with a fresh pencil in the new exchanger. Every time the boat sits for four days or so I still get a shot of zinc out the exhaust on the first startup. Im pretty sure thats what it is as oil is clear with constant level and water level is same as other motor. Plus you can see little chunks sinking. I pulled the pencil yesterday and it was evident that motor must be alive with electrolysis. For three weeks it was suprising how much was gone.

Wanted to run my plan of attack by you guys and see what you thought. I always turn battery switches off when leaving the boat. The only DC that remains live is the bilge pumps which bypass the switches. Im figuring if I disconnect the ground wires (one to battery and other to second motor) from the lug on the engine and place a milliamp meter in series with the block/battery I should be able to read any stray current through the motor. From what I have read .3ma seems to be the threshold that constitutes a “hot” engine vs one that does not have stray current. If engine is ‘live’ I plan on disconnecting things till current drops and work backwards from there. Any advice is greatly appreciated before I dig in. Oh and last but not least, I plan on starting motor with sw hose disconnected from elbow and shooting in pail for few seconds to catch whatever is coming out of the elbow first for further inspection.

[Roger bing]

Hi Tony:

As far as time, i am not sure. I am not the first owner of the motor. And the system has not been pressure tested. What would I be testing for it was pressure tested? The new exchanger is installed and fw side is holding water.
I was not suprised by the failure of the exhanger. I totally understand they fail from time to time. What Im more worried about is potential electrolysis. I change engine zincs routinely and never see them deteriorate that quickly. Going to pull them out of port motor today to see if they are as bad.

[Roger bing]

Best case scenario is you popped a clamp or simply blew a hose on the discharge side of your turbocharger. I’ve seen this happen on multiple engines and they all showed the same symptoms. My first check would be all hoses and clamps from the turbo discharge to the intake manifold.

[Roger bing]

thanks for the replies. not sure as to the era the cores were from, but they definitely looked like copper vs. aluminum. i ran the boat today no issues.

[Roger bing]

That’s some picture… I hope that’s all it is .. you’re not fearing anything with water intrusion into air side?

[Roger bing]

i have two tanks (one per motor) at 160 gallons. they are under the cockpit floor aft of the engines. the longest run would be around 5-6 hours to the canyon when full, trolling and coming back. so motors could be running for 18hrs straight. upon returning home i have around 50-70 gal left in each tank.

[Roger bing]

sorry for the late reply. in our travels since my last post, i actually found a cracked exhaust manifold. which was welded and replaced. apparently the #1 hole on the manifold was a problem on the marinized 60’s . detroit even added an additional fresh water feed to the front of the manifold in an update as they were not circulating well in the front end of the motor.

yes tony…. the 825hp is a 12.7L. I agree with you and told the owner to first swap the boost sensors from engine to engine and see if the lag transfers motors. they are easy to get at.

as for the injectors i changed at the 3000hr mark, the “lagging” motor now throws clean exhaust water at 2350rpm and 99% load while the starboard is pushing black water at same rpm and load. owner is set on doing starboard injectors in spring. they are due lol.

[Roger bing]

I got the same impression as I had the boost issue with my 300 cummins in my boat where the acceleration lagged throttle position. I got the code reader back and am going to run an injector test again to assure we didnt get a bad injector from detroit diesel. After that ill look into how the motor balances boost and fuel during acceleration. I was moving around the back of the motor by the turbo to bleed the engine.. perhaps I knocked somthing off.

[Roger bing]

sorry for late reply. i was a jackass. 20+ year old seawater strainer with cork gasket was issue. when i pulled gene out to replace pan, I cleaned strainer. eventually i tried bypassing strainer and unit never shut down. it was the high temp cutout tripping unit out when running due to vaccum created in scoop.

[Roger bing]

yea that was some ride…. I was even wondering if it could be a fuel issue causing high exhaust temps. ..problem is i cant think of any easy way to determine which switch is cutting out on me.

[Roger bing]

I was running sae 30 prior to takeout as the manual recommends for temps over 80. However it says 10-30 is acceptable over a wider temp range. I will check out seawater flow and check for intake restriction.

[Roger bing]

Yes, boat was in water all year. However, she was just hauled and intake is clear. The entire machine was removed from boat in December and gone over when I replaced the pan. New Impeller, pan, hoses, cleaned heat ex., etc….. It is only tripping on fault while underway in ocean. I ran it for over an hour in the bay while i idled back to my slip in the calm water. It will restart immediately after shutting down therefore I would imagine overheat not an issue as the switch would still trigger and prohibit restart right after tripping. That leaves me with EGT and oil pressure. Im going with oil since I changed pan. I have 10-30 in it as per manual. Will change with sae30, check exchanger header, and run again.

[Roger bing]

Tony:

Thanks for pics.  Im pretty sure the plug in the water pump return line is 1/2″. However, the bushing that is currently in the turbo flange blank on top of the exh. manifold looks to be 3/4″.  Is that part of the blank 3/4″ npt?

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