Aftercooler pipe failure

[Russ Keyes]

Just had a Cummings reman 6BTA 5.9 370 HP installed on the port side of my 46 Maxum. At the same time had the heat exchangers and aftercooler serviced on starboard engine also. Went out for a sea trial ran both engines at 1500, 2000, 2500, and full throttle 3100. Strobe tach showed 50 rpm difference from boat tach. After about 3 minutes at full throttle there was a large bang. Mechanic was in the bilge and I at the upper helm. Brought throttles back and mechanic said the hose clamp on the starboard engine aftercooler pipe to the turbo had let go. Reattached it and stepped up to full throttle again. Shortly there after the starboard engine began to loss RPM’s so pulled both back again. Mechanic said there was a problem with starboard engine. Ran it at 1500 RPM and there was excessive black smoke coming out of the Seaboard CCV air cleaner. We have started to checking to see what the problem is, no conclusion yet.

My question is could the first problem have caused the second problem? Seemed odd that one happened right after the other.

Thanks,
Russ

Topic

[Bill Desmarais]

That is lousy

[Bill Desmarais]

That is lousy

[Russ Keyes]

Looks like we have a bad piston and metal in the oil filter. I sort of doubt the aftercooler pipe failing caused that. Thanks for you help on this. Looks like a long block. Russ

[Bill Desmarais]

OK,

a few more questions ?

After the “big bang” at wide open throttle and you brought the engine back to idle…was the 370 running OK?
Like normal at the dock, running smooth on all six cylinders?

And you checked the turbo free spin with your fingers after the bang?

And finally the stainless steel (Cummins painted the tube white) tube between the turbo and the after cooler…you looked it over for cracks, splits holes etc. ?

btw, you can buff up all the paint off the tube..shine it up to a nice shiny SS finish…looks nice 🙂

Keep us posted

Bill D

[Russ Keyes]

There was no black smoke out the exhaust. There was black smoke coming out of the air cleaner. The aftercooler was removed taken apart cleaned and pressure tested. We’ll check those items Monday.

[Russ Keyes]

The loud bang was the escape of pressure. We are just going to start that process. Happened on Friday. I am hoping that what seems to be a back pressure is not another bad engine.

[Bill Desmarais]

Questions ?

Was the “loud bang” you heard simply the clamp breaking on the silicone hump hose and the escape of pressure that was at 27psi to 30psi in the turbo air tube?

I had the same clamp break on the hose on the same engine. Every time I pushed the throttles forward and the turbo built pressure…around 2,000 rpm I’d hear a LOUD AIR HORN from under the engine hatch…..and I mean LOUD……….took me a few days to figure it out.

From the info posted……IMO…check the tube for a crack…check the silicone hose for a split…..if all OK, replace the clamp or double clamp…..

Keep us posted,

Bill D

[Rob Schepis]

When you pushed the throttles back up and the starboard engine starting losing rpms was there black smoke out the back (exhaust)?

What did the starboard aftercooler serving entail? Removal, separated on the bench, final pressure test, etc ?

After the issue did you pull the air cleaner and/or exhaust elbow and check the turbo?

How about the air hose from the top of the aftercooler to the intake, check that for moisture?

[Author]

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