Survey result - question Cummins 370 Turbo Charger

[PJHoffnet]

Had a survey and sea trial on a 2000 Carver 404 with twin Cummins 370s.

Boat is in really good shape cosmetically, mechanically and electrically wte of a lot of blistering below the water line (time and $ consuming, but nothing that points to a disaster).

The only real problem noted in the survey that I'm concerned about is the turbo chargers on both engines. Both showed excessive rust and corrosion during the pre-underway survey, and during sea trials we couldn't bring the engines above 1800 RPM, so the turbo chargers never kicked in. The surveyor and I figured the turbos were frozen shut and passed that info on to the seller as a 'must fix' followed by a re-survey.

Seller's broker came back after having her engine guy look at it and said turbos are not frozen, but (and forgive the wording here, I didn't take the call and am working off the notes my wife took and her recollection of the conversation) that the pitch of the props are wrong and that's why the turbos never got a chance to kick in. They said they'd haul out, 'fix the pitch', (I can only assume they mean change props) and be ready for re-survey soon.

Ok, now we're not talking about a destroyer with veritable pitch propellers here, and I suppose it could be as simple as changing to a correctly pitched propeller for the engine.

Stbd and port turbos





Prop, probably doesn't help, but only one I had


Thoughts? - Thanks in advance

[Midnightsun]

My question is how in the world did the props get so over pitched that 1800 rpm was the max? Unless they somehow put on the wrong props, I cannot see this as being the problem. Maybe barnacles and bottom growth but not wrong pitch. Just make sure they do not re-pitch to accommodate the low rpm in a shady fashion. Someone here will chime in as the what to expect at WOT when it comes to speed and rpm with those Cummins diesels and go from there. Something is not quite right here.

[PJHoffnet]

Bottom was clean, so that can be ruled out.

[tomschauer]

I am sure many people on this forum have much more diesel experience than I, and I am sure they will offer some opinions, but if the turbos were not spinning at all, the boat would have been smoking like an 1800's locomotive at any rpm.

Best of luck.
Tom

[bud37]

Might be a good idea would be to hire a diesel mech. and have him do an engine survey if its not too late as those things are very expensive to repair even if you can find a good competent mechanic........now a friend had a boat with over propped diesels, boat would not go on step....lots of noise and much black smoke from the fuel it couldn't burn, that was the giveaway. It ran fine otherwise and at 1100 rpm he was doing 7 knots that was with 1.5 gears. Just a little bit of anecdotal stuff from me......check your low speed against rpm, that should give you an idea....most any good prop shops will be able to assist with that info........

[waybomb]

What Bud said about a mechanic.
I'd rather pay a mechanic a few hundred dollars now than a few thousand after you close and find out both turbos are locked up

[PJHoffnet]

Seller already has a haul out and re-prop'ing scheduled to be followed by a follow on survey with my original surveyor and his engine guy.

[mjk1040]

PJ, re-pitch and re-prop are not the same. Re-pitch means they will change the pitch of the props that are on the boat now. I too question this. Props are stamped with the diameter and pitch on them when they are made. If they were taken to a prop shop for minor repair they should have been returned close to new. Has this boat been sitting a lot? If so I would lean more toward bad fuel or restricted air flow. Now I have to tell you that Carver would change the pitch of some props to keep an engine from over rotating beyond the recommended specs. I hope his engine guy is a cummings man. Good luck and I hope you get to enjoy her this season. Mike

[waybomb]

I also would be very leery of needing a reprop. Or even a repitch. 1800 rpm seems way way low, not just slightly. I think this engine is rated at 2800 rpm? This is not a prop problem if 2800 is in fact the sweet spot.

If those props are stamped with the correct pitch/diameter, the same as Carver put on originally, I'd be thinking a much bigger mechanical issue is at hand.

[Viper]

No mention of excessive smoke so I assume none was noted which tells me the turbo is spinning and providing proper boost. Is there a boost indicator on board? When the engine is shut off, does the turbine stop spinning right away or does it keep spinning for a while before coming to a stop?

Have the fuel filters been serviced? Are the bowls clear or do they look like a science experiment? If they're starving for fuel, you won't achieve rated rpm. If they're going through the expense of hauling out and going for the props, I assume/hope they checked the simple things first.

Is it me or does the flange at the turbo mounting look warped?

From the picture, it almost looks like the turbo casting is crumbling where the mounting bolts would thread into.

Looks like there are exhaust leaks at the turbo mount, and usually when I see rust trails like that shown at the water injector tube, it usually means pin holes as they don't seem to be running down from anywhere above, unless there is something dripping from above that location or from above the engine.

Without being there to sight it properly, it's difficult to tell but from the picture alone, the rudder seems to be kicked in quite a bit. While some are designed to be toed in a bit, that seems like a lot but I suspect it's just the angle the picture was taken.

Without actually being there, it's hard to say for sure whether any of the items that raise a flag to me are of any real concern judging strictly by the pictures. If you're not there and can probe deeper or sight things from a proper angle, it's difficult to tell if there are any real issues and an opinion is an educated guess at best. One hopes that someone that's physically there can say for sure if these are legitimate concerns.

Keep us posted.