40 sedan bridge forum

[NaughtyDog]

Can you post pictures of exactly the area you are referencing.


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Here's a pic of the area I was speaking of for those interested. This picture was taken from inside the compartment under the galley floor looking aft. The hidden space I was speaking of is just aft of the compartment where it steps up to the level of the AC unit. It's inside the boxed area you see in the picture.


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[cwiert]

Signed papers today! With any SERIOUS luck, we'll be proud owners by the weekend. I'm not holding my breath but hey, a guy can hope. Besides, the weather doesn't look too good up on Lake Michigan this weekend for a maiden voyage. Fingers crossed!

Good luck! Hope it all goes well. I'll be at the boat tomorrow and can get a measurement of the aft locker for you. But no ordering names until the boat is yours! Don't jinx it!

 

[ZZ13]

Did the mechanic give you a measurement on the fin clearence? It does look wide, but pictures and shadowing can be misleading. What did the risers look like inside?
What you are describing sounds like what i found inside my mixers, and all the research says this is "normal" as the mixers do have a shelf life in a salt environment. I'm not a believer that bonding would have made any difference. The engine is grounded, so is the turbo, and the mixer is just the same. I'm not a metallurgy type guy, but suspect the right mix of salt spray, and diesel exhaust cause this to happen in stainless.......

Although my turbos did not look as bad, i do believe they were experiencing salt spray from a leaking mixer.....much like what you are describing. I skipped the stock design, and redesigned with adding a 9" dry rise hump. FWIW I believe this is a common problem with Cummins and 40 sedan bridge boats. In the next few years I suspect you will hear of more problems related.....some catastrophic, unfortunately.

As the purchaser of the boat at the 12 year mark, I have learned that just about everything on the boat other than the engines has about a 12-15 year life. So those of use owning the boat during that period pay the price of almost a refurb of the boat. I'll just add the mixing elbows to that long list of items I have replaced in the 12-15 year period. The list is impressive. I have also learned I wouldn't nearly pay as much as I did for a 12-15 year boat that still had all the factory original stuff on it - even if it all worked at that time. You'll be paying to replace it all in short order.

As far as a redesign of the exhaust, hope that works out. I know I won't have the boat 15 years from now so I am good with replacing with the factory version when necessary.

Do the Cat 3116/3126 owners have the same mixing elbow/exhaust system?

 

[Zephyr]

Best of luck Bill


I should have all the parts to do the repair work in 2 weeks – I will also post a few pictures of both the turbines and the mixers.

 

[carterchapman]

Do the Cat 3116/3126 owners have the same mixing elbow/exhaust system?

Bill, I'll let FrankW answer for sure, but I never had a problem on mine, and have not heard of any. I think Impulse III had his shower heads cleaned tracking down what turned out to be another problem...

 

[Zephyr]

Did the mechanic give you a measurement on the fin clearence? It does look wide, but pictures and shadowing can be misleading. What did the risers look like inside?
What you are describing sounds like what i found inside my mixers, and all the research says this is "normal" as the mixers do have a shelf life in a salt environment. I'm not a believer that bonding would have made any difference. The engine is grounded, so is the turbo, and the mixer is just the same. I'm not a metallurgy type guy, but suspect the right mix of salt spray, and diesel exhaust cause this to happen in stainless.......

Although my turbos did not look as bad, i do believe they were experiencing salt spray from a leaking mixer.....much like what you are describing. I skipped the stock design, and redesigned with adding a 9" dry rise hump. FWIW I believe this is a common problem with Cummins and 40 sedan bridge boats. In the next few years I suspect you will hear of more problems related.....some catastrophic, unfortunately.

Good point – the mixers and the engine should be at the same potential, depending on the gasket material. Thinking back to when I first removed them, the gasket from the exhaust to the turbo was a thicker one than the standard Cummins part - maybe that was the issue?!?
I’m going to bond them and monitor every few years. The cost is minimal, will reduce corrosion and makes me feel better about all the money I’ve just thrown at the boat….
Good idea to redesign, the cost is hard to justify (unless you do an engine…) for me, unless I planned to keep the boat for a long time.

 

[Zephyr]

Did the mechanic give you a measurement on the fin clearence? It does look wide, but pictures and shadowing can be misleading. What did the risers look like inside?
What you are describing sounds like what i found inside my mixers, and all the research says this is "normal" as the mixers do have a shelf life in a salt environment. I'm not a believer that bonding would have made any difference. The engine is grounded, so is the turbo, and the mixer is just the same. I'm not a metallurgy type guy, but suspect the right mix of salt spray, and diesel exhaust cause this to happen in stainless.......

Although my turbos did not look as bad, i do believe they were experiencing salt spray from a leaking mixer.....much like what you are describing. I skipped the stock design, and redesigned with adding a 9" dry rise hump. FWIW I believe this is a common problem with Cummins and 40 sedan bridge boats. In the next few years I suspect you will hear of more problems related.....some catastrophic, unfortunately.

My mechanic did give me the measurement on the fin clearance – but I cannot remember the exact value. He looked in the turbo, wobbled the shaft and showed me the clearance – I think he said 20-40 thou but it was more like 80-100? I will measure the new ones and the old when I do the job and let you know

 

[ZZ13]

Here's a pic of the area I was speaking of for those interested. This picture was taken from inside the compartment under the galley floor looking aft. The hidden space I was speaking of is just aft of the compartment where it steps up to the level of the AC unit. It's inside the boxed area you see in the picture.


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I understand now. What does everyone think of using a hole saw either on the top or forward side to put one of those screw in access caps. So you could check it now and again and get a shop vac hose to it if needed.


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[ZZ13]

Anyone got a moderately decent measurement on the stern locker? My wife wants to get going on the name for the boat and I have never measured the door to the stern locker. Our boat is 3 hours away still, and...well...still not ours. We're close.

49" wide.


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[Prosideus]

I think the idea of an access hole on the top side makes sense. I would not cut the vertical panel. Two things to consider. The space to cut and access the hole will be very limited to the side of the AC unit. Secondly, what is under there that is of importance that you may puncture or cut? We may need Rusty to weigh in on whether that is an empty void or something else....


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[PMC]

As the purchaser of the boat at the 12 year mark, I have learned that just about everything on the boat other than the engines has about a 12-15 year life. So those of use owning the boat during that period pay the price of almost a refurb of the boat. I'll just add the mixing elbows to that long list of items I have replaced in the 12-15 year period. The list is impressive. I have also learned I wouldn't nearly pay as much as I did for a 12-15 year boat that still had all the factory original stuff on it - even if it all worked at that time. You'll be paying to replace it all in short order.

As far as a redesign of the exhaust, hope that works out. I know I won't have the boat 15 years from now so I am good with replacing with the factory version when necessary.

I agree completely on the 12-15 year comment, and yes that comes at a cost. The silver lining is that you do know every detail of every system.

Different drivers for different people. I was very close to purchasing a stock riser, and calling the project done. However a few items were weighing on me heavy.
-They are expensive and don't last very long. I've heard stories as short as 5 years
- Close to turbo waterline (~8 inches) The lift mufflers help in ideal situations only, and are not inherently safe without exhaust preasure
- I saw the damage from salt water, and wanted to reduce my risk
- The boat has the room to improve
- Going custom was cost comparable

 

[my3sons]

Just wondering why if you guys are so concerned about salt water damage to your systems that you don't rig up a fresh water flush. Seems to me that if you use a boat for the weekend and then let saltwater and salt residue sit in it all week until the next weekend, or whenever, is just crazy as easy as a flush system is. I would think you would want to flush it anytime it is going to sit more than a couple of days.

 

[fwebster]

I'm not a 400DB guy, but I've had diesel engines in saltwater for 20+ years. These are not Mercruiser gas engines. Marine diesels are a completely different design in that seawater never touches the engine block, heads, exhaust manifolds, etc. Seawater enters the heat exchanger , flows thru the fuel, oil and transmission coolers then exits thru what is called the shower (exhaust elbow). Some engines have aftercoolers that are seawater cooled, others are cooled by the engine's antifreeze. So, there are no cast iron (rustable)parts that contact seawater. The heat exchangers, coolers are brass or bronze and most showers are either cast bronze or stainless. Therefore very little good is gained from freshwater flushing a diesel engine since no seawater is in them. You will get some lime deposits in the heat exchanger and coolers, but a descaling flush every 2-5 years is adequate for cleaning since they do not rust or decay like a cast iron engine block, a manifold or risers.

Having said the above, maintenance is the key to longevity. When we buy a used boat, unless we have a detailed service record, we never really know what it inside until something happens. Here on the Gulf Coast, it does seem that some engine makes have more robust designs and don't surprise us as often as others. We do see more failures where the engine maker chose to use a welded stainless steel elbow and shower assembly as opposed to cast bronze or stainless steel.

Hope that helps the discussion a bit………Back to you regularly scheduled programming.

 

[my3sons]

Frank, glad you chimed in, you certainly know what makes these things tick. We're not talking gas motors here, and understood the Cummins design is not as good as some, the aluminum aftercooler cases of the cummins are a pita corrosion wise. When the water drains out after shutdown through the shaft seals and what leaks back through the raw water pump, it leaves the aftercooler half full of saltwater. And I guess we have all seen the pictures of clogged up tubing bundles in aftercoolers and heat exchangers regardless of manufacturer. The discussion was in regard to the stainless mixer on the Cummins, so don't you think a flush system might help? Maybe I'm over thinking it, but the guys involved here are in 16 year old boats, Lets just say they have 1300 hours on them, that's 2 months of run time, the other 15 years and 10 months of the time the salt was just sitting in there doing it's thing.
OK, maybe not that bad if a northern boat that gets hauled half the year, but seeing that 2 months next to 15 years looks good for the point I'm trying to make I know what my freshwater aftercoolers look like on the inside, and I know that at least one of the saltwater guys here with a Cummins powered 400db had to throw away 2 aftercoolers because of corrosion. Those things aren't cheap. For the couple hours of time and less money than a fuel fill up, I felt it was worth it before bringing the boat south to rig up a flush system. If they don't want to bother, I can get that too, but one guy just spent some money on custom mixer elbows and one with brand new aftercoolers. These guys are kind of starting new.
Salt water isn't evil, I have loved my winter in florida and will definitely be back, But I will be flushing if I pull into a marina for more than a couple of days.

 

[fwebster]

I understand the concern.

Would I rather leave freshwater in an aluminum cooler housing? Yes, but that opens a couple of other questions……….Will you run the engine while flushing, if so, how will you flow enough water to flush the engines from a dockside water hose. Somebody did the math based on 55 psi of water pressure, but that is a pure figment of your imagination around where we are. You are lucky to have 1/2 that on a weekend when other boats are being washed, etc on your dock. I flushed my 7.4's in the old 390EC and the engines collapsed the hose because they used more water then the line supplied. The risk is galling an impeller or overheating an engine.

I think if I were going to flush a diesel, I would use a salt neutralizer instead of just water. I kept a 15 Whaler here for several years and washed the boat and flushed the motor every day out with Salt-Away and when I sold the boat, you really couldn't even tell it had ever seen salt water.

There is wishful thinking, but the aluminum after cooler housing is one choice I bet most Cummins owners would have gladly paid the cost of a more durable metal on the front end rather then over and over as the engines age.

 

[ZZ13]

The air side of the after coolers has been my only salt air environment issue. The water side has had no issue. The tube bundles in the after cooler, oil cooler and heat exchanger have stayed perfectly clear in 4 years of salt water use. I check them every two years. This is without freshwater flushing. I make a point to run the engines to temp at least once a week. I tried freshwater flushing for a while and like Frank said, I had to leave seacock open as not nearly enough hose flow for the seawater pump. The water was still a bit salty. Decided it wasn't worth the effort. I deduced that I should just run the engines as often as possible.

This mixing elbow concern is a new thing to me. I never considered it before this latest series of posts. My 16 year old port mixing elbow is fine. Will be checking the starboard soon. One difference is the port has a long run of about 4 feet of hose before the water/exhaust gets to the lift muffler. The starboard side has only a short 1 foot of hose before it gets to the lift muffler. Don't have any idea if this means anything, good or bad.

 

[my3sons]

Bill, interesting that your corrosion was on the air side of the o-rings. I agree that a garden hose is not enough water. I knew from winterizing that the motors will suck down 6 gallons of antifreeze in 15 seconds. To flush I draw through a 1" spa hose from a container while running both the dock hose and the E/R washdown hose in wide open. The 15 gallon container empties in between 2 and 3 minutes. I estimate 40 to 50 gallons of water goes through.
It has to help. Only another 6 weeks to go and I'm back in fresh anyway.
In regard to your concern about the muffler, as an experiment sometime, remove the plug from the lift muffler and allow the standing water to drain out. Then get a couple of your dock buddies to rock your boat side to side while you listen in amazement (at least I was amazed) at the amount of air being forced in and out of the exhaust system by the rising and falling action of the underwater exhaust. I saw this at a marina in Belhaven, we were being broadsided with 40 kt gusts and 4' waves. There was no breakwall to the direction of the wind. As the boat pitched and rolled, water would rise up into the cockpit through the scuppers on the down stroke and then run back out on the up stroke. I was concerned about the mufflers filling up so I pulled the plugs out, the air moving in and out of the mufflers sounded like bellows, but they never got any water in them. Wonder if when the plug is in if air moves in and out of the turbo through open exhaust valves?
I think I slept a total of about an hour that night.
Salty air and salty water is just part of the fun I guess.

 

[ZZ13]

Today I took a break from thinking about exhausts and finally did a project that's long been on the list. I ditched the two phone jacks and replaced them with another pair of 120v outlets. I removed both Vimar installs in the master stateroom and replaced them with off the shelf stuff.

Then I moved the Vimar outlet in place of the phone jack in the salon so they would both match.

Total cost was $12. Next is to add an outlet to the starboard side of the master stateroom and one to the dinette area.


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[oceanpearl]

solved

 

[PMC]

Here are are a few pics of my exhaust progress.


Stock water cooled mixer. I cleaned up and confirmed it was leaking. The before picture looked like tar and rust. This is sandblasted

This is the tack welded riser. I added a 9" dry rise, and a downward slope mixer.

Here are the finished items with a thermo blanket. I really wanted to go with a hard coat epoxy shell, but that added another 6 weeks to the project. I was already cutting my time line close, and cannot afford the delay. The blanket will do just fine.

Port side installed. I have plenty of clearance to the flook.

So far I'm happy with the project. I'll run the boat in a few days