Sheared bolt inside C450 Turbo

[Mark Theyer]

Hi SB crew

I have a Riviera 4000 offshore express on Gold Coast, Queensland which features 2 x 1997 6CTA8.3 aka C450 Diamond Series with around 1000 hours on the tachourmeters. The other morning I found a bolt in the engine room and it is from the turbo where the exhaust bolts to the turbo.

Please refer attached photos. Recent running was not hard and last couple of runs before this discovery we were only doing a leisurely 10 knots or 1100rpm. 

My question is has anyone got any tips on how to remove the bolt and what parts will I need before starting on this repair? Looks like we should replace all of the bolts in both turbos… and my fear is that other bolts may shear when I attempt to remove them.

Thanks for your help!

Regards

 

Mark Theyer

My engine specs are:
Cummins 450C (SW) x 2 Diamond Series Model 6CTA8.3-M3 July 1997
Port 45551870
Starboard 45551778
Sherwood Sea Water Pump
Racor Diesel Fuel Filter / Water Separator 900MA 90GPH (340 LPH)
Fleetguard WF2074 Coolant Filter
Fleetguard FF5285 LF3000 Lube
Transmission MG5061A
Shaft 1 and 3/4 inch TEMET 25
Shaft Seals PSS 1347AF Palmetto Style
Props 23×27
33 knots GPS SOG 61 km/h

Topic

[Mark Theyer]

Hi SB Crew

After almost 8 years to the day we sold our beloved Riviera.

In due diligence we pointed the new owner, Rodney to your awesome site, this forum and these specific topics. In those 8 years we never had the rocker covers off … not saying that is a good thing… but lucky for us we never had a failure. Also never got to install my new SMX sea water pumps.

The best thing we did was to plumb fresh water input after the sea cocks. We used two hoses to a Y connector into half inch pipe… and that was just enough to feed one engine at idle. The anodes lasted for years after that because I always flushed after every weekend. I never understood why salt water diesels never got fresh water flush.. but I grew up with outboards. 

So its back to the ski boat for some wakeboard and tubing fun. Bought a windsurfer and SUPs for the girls.

Happy boating. 

Mark

 

[Clark Leighs]

Mark,

Look up Tonys tips about exhaust systems.     Seriously read them and you will see what is wrong with your system.     Fixing headaches like yours is a goodly part of his business and he has become expert at it.  Learn from him and his willingness to help.

A dry riser , blanketed for heat containment, can be fabbed and installed immediately after the turbo so the actual riser goes UP steeply.  You have the room it looks like.    Then a sharp downturn , THEN the raw water injection AFTER the downturn    and then the new piping can join the older existing  piping to the  transom.

You may still need new turbos but get that riser attended to soon or  the seawater may actually get to the engine damaging it to boot.

 

If you cannot afford both parts of the repair get the riser done first to prevent further degradation.  Then get the turbo cleaned at least to remove the loose rust as any of that getting into the engine could be trouble.   Then deal with the replacement turbos as soon as you can.  

And check what Tony suggested about the valves stems.  If they stick at some point and it slaps a piston then there could be catastrophic damage.

 

JMO    as I am no expert but I have seen enough on the forums before to recognize you are headed for potentially serious trouble.    

 

[Tony Athens]

Mark,

It appears that with some cleaver design and engineering, you have the room to build a proper set of risers similar to the attached……….Cummins should have never allowed this design to go pass muster as it does not even follow their own written rules..

With that said I’d be very worried about your exhaust valve stems on the aft 3 cylinders.. The condition of your turbos show conclusively they have been eating salt water for well over a decade.. Note: this would not be the first time I have seen the stems break of from severe corrosion caused for exhaust designs like this….Your broken / hard to remove bolt is not your real issue.

Tony

[Stephen Oliver]

The main issue hasn’t been resolved then? The fact that your turbos are getting washed by saltwater due to poor exhaust design. You may think they are performing ok but looking at them you will be down on boost, and if they are like the ones I have just taken off mine, too badly rusted to machine and sleeve. I had nearly 10mm clearance between the turbine housing and the blades at the bottom, but the engine still ran and got close to full revs, albeit a bit sluggishly.. it also put a heap of load onto the starboard engine. I have no doubt that the starboard engine on mine was being worked too hard and due to lack of boost on the port the exhaust gas temp (egt) was too high which would have eventually taken its toll…

A new set of risers using all available height would certainly help .. it’s worth taking the time to absorb all of Tony’s info on exhaust design and his doomed to fail section. The issue could take out the turbo, the manifold and even the engine.. a couple of grand for a set of well designed risers could save tens of thousands long term. Unfortunately it seems to be part for the course for most boat manufacturers, be it Riviera, Carribbean or any of the American boats.. the majority have crap exhausts…

Steve

[Mark Theyer]

We had to machine one of the exhaust elbows but otherwise it all went back together just fine. New bolts and treated with anti sieze goo. The issue was caused by a broken rusted bolt so the task was to remove and replace with new bolts on both engines.

[kknoth007]

Turbo Dave in palm beach florida

We had our turbos done by a local guy who has a cnc machine. he cuts out old crap in housing and presses a sleave into housing. like new. He even closed the gap between the wheel and housing increasing boost for free power (there is some gap needed for expansion)! This is in south florida but maybe somebody local can do same?

[Mark Theyer]

Re: Salt Water Cooled Turbo

Thanks Tony love your no BS comments. Please refer attached for pics of engine bay and lift mufflers.

[Tony Athens]

Now that’s what I call a “Salt Water Cooled Turbo”..

Post some good pics of the engine as installed along with pics with the factory installed exhaust system.. I’d like to see how how much some idiot at Cummins saw( who was suppose to and required to to approve the system), when he stamped it “OK“…

Plus then I will give you an idea of what you may be able do to “save your engine” fro more of this………

Tony

[Mark Theyer]

Follow up

Hi guys

Just a follow up. Got the turbo exhaust ports off both engines and replaced with new bolts… had to drill out the sheared bolt and rethread. Here are some photos of the turbos. Lots of corrosion but fortunately both engines are running smoothly with no issues. In this Riviera 4000 the lift mufflers are not far away and not a steep gradient either, especially on the port side… so when engines are off I think the sea water could slop back up to the turbos when the vessel rolls heavily in a wake or waves. Any feedback or opinions on their condition would be appreciated.

I secretly have a wish list to replace the sea water pumps and the turbos… but they are all still working normally. I don’t push these engine past 2000rpm and that gives us easily 22 knots. The majority of the time I am cruising at 1000rpm with my feet doing the steering… slow and steady.

Regards

Mark

[Mark Theyer]

Thank you all for your generous feedback.

I have talked Tennis friend Darrin into helping me who hates working on marine diesels for exactly this reason (he just does cars these days). We will attempt to remove the elbow and the bolts and inspect the turbo. Worst case I guess the turbo is replaced and we get a bit sweaty so not the end of the world, just a pain. Live and learn… for example, I have learned to inspect my seawater side impeller, plugs and aftercooler regularly. Slowly getting on top of it all after two years.

I never realised that owning a larger boat would require so much love, time and attention. I have a ski boat in the garage I use once every six months… it starts every time and all I do is put fuel into it and flush it with fresh water when she comes out. I guess though it is kept in a nice dry garage away from that nasty brine!

I will let you know how we go… more story to tell!

[Rob Schepis]

Low Profile Bolt Out

The low profile ones fit, I’ve used them just for this.  They have hex sides for use with a wrench

 

[james]

The challenge with those bolts, is there isn’t enough clearance to get any sort of socket on it.  I ended up taking a 6 point 10mm box wrench and welding it to the handle of a 12 inch adjustable wrench.  This effectively gave me a 18 inch breaker bar.  To my eyes, it is a very poorly designed component (the exhaust elbow).

[Rob Schepis]

Extractors

These extractors work very well when the bolt head starts getting a tad  “rounded” 

[Rob Schepis]

That plug is just an EGT port, has nothing to do with the removal process. 

Access looks pretty good, can you cut the heads of those two bolts off with a die grinder cut off wheel or such?  MAPP gas torch and candle wax trick “may” work, it did for me on one stubborn bolt ..

 The turbo is likely shot but it would be easier to take things off in components and getting the elbow off first will get you a look at the turbo outlet…

[Louis C Glover]

Reply To: Sheared bolt inside C450 Turbo

I had the same problem with my turbo with 4 broken bolts. After removing from engine I tig welded a 3/8″ nut to each broken stub and was able to to unscrew them. I also used candle wax on the welded nut as it cooled as a penetrant.  Be sure to put anti-size on the new bolts.

Louis

[james]

Had the same problem

Those small bolts are a real weak point.  I had the same problem on my boat, and yes, the turbo and exhaust had to come off and be sent out to be cut the bolts off.  We were replacing the turbo’s, so it just made the job a little harder.

The mechanic mentioned to me that it is very important to drain the coolant prior to removing the Turbo.  He probably pulled 3 or 4 gallons out prior to removal.

I now back those bolts out every 6 months or so, to try and keep them from freezing up again.

 

[Mark Theyer]

Removal of Exhaust Elbow failed

Hi SB Crew

Unfortunatley I have failed to remove the exhaust elbow from the turbo.

The second lower bolt simply broke off and the two top bolts will not move at all. I have plied with penetrant several times. Not sure what the next step is, I am wondering if the whole turbo needs to come off… and send the lot to the shop. What is your opinion?

I have attached a couple more photos. By the way I could turn all four similar bolts on the starboard side engine although it shows less sign of rust oxidation.

What is the allen key pin for, alignment? That suggests the turbo has a inner tube that the exhaust elbow slides on to, yes?

If the turbo needs to come off do you have any tips on removal of oil and coolant lines?

I am thinking if the turbo is too rusted with are bolts stuck inside it may needs to be replaced?

Thanks for your feedback

Mark

[Rob Schepis]

What is the general life of these turbos…

Well if there was ever a question without a single answer that is one of them.

So many factors:

Is the air side always sucking in salt laden air?

Is the outlet side on a seawater diet?

Is it sitting at rest in damp conditions?

Is it under a leaky deck?

Is is under a leaky gear cooler?

Is it subjected to high heat due to overloading?

You get the drift….. It “can” last for decades but is often only allowed a shorter life due to issues external to it that are no fault of it’s own…

It requires visual inspections internally by removal of the exhaust elbow and air filter, check for corrosion, tip clearance at the blades/housing at the exhaust side, play in the shaft, etc. Performance issues would be loss of boost, low power, black smoke..

[Mark Theyer]

How is performance?

Thank you for the feedback. The performance of both engines is good and appears normal with no black smoke at any time or on the plane.

May I ask, what is the general life of these turbos and are there any signs or indicators of wear or when they should be replaced. For me I would replace with your brand new turbos since it would likely cost me as much or even more to have them reconditioned here in Australia.

[Rob Schepis]

Elbow/Riser Mounting Gaskets and Hardware

The graphite gasket is thicker and can make up for any imperfections in the mating services.  If all is “as new” you could get away with no gasket at all, just some the Permatex ultra-copper high temp silicone.  Yes, anti-seize on the bolts.  FWIW, on my installs I had new risers mating up to a new turbos and I elected to go with the graphite gaskets.

[Author]

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