Cracked turbo? QSB5.9-380

[Brian Rapp]

2006 Tiara Open 3600, twin Cummins QSB5.9-380s, around 1,010 hours. I purchased boat in July 2020 out of fresh water, and now it’s in salt water. Engines generally start/run great, just traveled Boston to NYC and back. Thought I noticed a little white smoke one or two times in my exhaust, but then it seemed to go away.

I changed the coolant last winter, and after 45+ hours of use this season, just had to refill my overflow (once). So it’s consumed about 2 quarts of coolant over those hours (mostly at cruise around ~2300 rpm, 11gal/hr; note engines reach ~3,020 rpm wot). Thought it could be my water heater, but started to inspect more things. This lead me to see the turbo…

Pictures of turbo show signs of a water stain and there’s a small glob of dried up blue goo. Paint looks cracked. Is this a crack in the turbo casting, with coolant leaking out? I’m not familiar with the internals of the turbo. Are these cooled by coolant, or could it simply be leaking out from a seal somewhere else? Looking back at videos from original purchase, this same stain on the turbo was there (and guessing this leak was also present – too bad for me the neither the Cummins tech nor I noticed).

I also serviced the aftercoolers last winter, which were clean on the water side (had been fresh water boat up until 15 months ago). Thinking back, on the air side, I did notice some corrosion like clogs on one end of the core (2″ high) but presumed it was just from moisture from air collecting. Guess some of the coolant may be sucked into the engine (and through the fins of the aftercooler core), but not sure whether that would have left any other specific visual cues. If coolant is being sucked in by the engine, what damage might this have caused? If still running now, will the risk go away if the turbo is replaced?

What else should I be testing, looking at, concerned about? Would any further use of the boat be a significant risk? I am guessing the turbo will need to be replaced (appears out of stock at the moment). Thoughts/questions/comments?

Topic

[Steve Lewis]

Tony,

Just getting back from Trawlerfest in Baltimore. Yes our mechanic did secure 2 heads. We are slated for head replacement over the winter layup. We will also get the Pyros installed that I bought earlier this year. I am changing the oil in the mains and transmissions this week and then we get hauled out the following week.

Then the fun begins as we are also having serious work done on the navigation electronics. Big winter for us.

[Tony Athens]

Steve,

Did you ever secure 2 cylinder heads? It took us close to 4 months to get just 2 of the 4 we ordered..

[Steve Lewis]

David,

I would just keep an eye on the coolant level in the overflow as it will probably stabilize as the system burps out air from the drain/refill. I have 480CE’s but saw the same thing as you did. I had everything cleaned as we just bought the boat in the Spring, so the coolant got drained and refilled. I have been adding little bits each weekend and now things have stabilized just in time for winter layup……….

We get to do it all over again next year as we are having our cylinder heads replaced over the winter, this time its for real. We will have to add coolant again next season until things stabilize. I would not worry unless this is a constant thing and does not stabilize.

1 user thanked author for this post.

David R Flamer

[David R Flamer]

Interesting post. We have the same engines and recently did a full cooling system service. Included servicing AC’s and HX’s. One of the HX’s was replaced with a new Cummins unit. Since then I have replenished close to an entire overflow container of coolant in both engines. This is after probably 30 hours of run time. They did not leak before this service.

We put a pressure test one one of the engines. No pressure drop.

The oil will get changed soon enough and, as always, we will do an analysis. The oil level has not increased, so I don’t expect to see it there. Nonetheless I am curious to see what it’s going to report.

I am not excited about it, but it may be time to look at the heat exchangers again to see if there are issues.

[Rob Schepis]

Yes that’s a coolant line/vent.

1 user thanked author for this post.

Brian Rapp

[Brian Rapp]

Thanks for the prompt review of the pictures and visual assessment.

1) That hopeful, thanks. Knowing there’s no coolant by design in there (guess just the oil feed next to it), certainly seems odd for fluid to accumulate there/leave stain on paint.

Is that hose that goes to the exhaust side of turbo carrying coolant (see newly attached picture)? It looks like it’s got a sharp bend, maybe there’s a pin hole that squirts onto the turbo (and has been for years), and the heat is just cooking it off (and corroding the aluminum?).

2) You and me both – more work to evaluate the surroundings.

3) I’m not a professional, but can change a timing belt and do valve jobs on naturally aspirated gas engines. Boat diesels specifically are new territory for me.

4) I’ll remove the air intake side via the removal of hose clamps and hose/filter this weekend.. Don’t think I can get my head under the output side to take a look inside there, but can try.

Will also sand the paint at the top and see if I can get the aluminum to clean up. What looks like rust may be some type of corrosion.

[Rob Schepis]

Quite odd. Chip off that peeling paint and wet sand that area down to bare aluminum.

1 user thanked author for this post.

Brian Rapp

[Tony Athens]

Turbo Crack – Coolant Leak ??

The attached picture tells me this:

1) You do not have a crack and you do not have a coolant leak , there.
Maybe some other place on the engine

2) At this point I cannot explain what I see, yet, other than #1

3) How “hands-on” are you?

4) The air side of the turbo housing needs to come off and thoroughly cleaned inside & out down to bare aluminum for a good inspection.. This is a 30 minute non-evasive job plus th cleaning time..

The rest:

Rusty looking stuff — 100% impossible as the housing is aluminum
Cracks– IMO, Too much paint
Blue/green stuff? No clue yet but there is NO coolant on that side of the turbo

1 user thanked author for this post.

Brian Rapp

[Tony Athens]

Resend you pics direct to me at [email protected]

As HIGH res as you got & clear & in focus—– .jpg attachments.. DO NOT embed them in the email or they’ll end up in my trash.

[Author]

Replies