Grand Banks 42 Classic, 1994 mufflers starting to weep a bit, input please

[inquisitivej]

I'm newer to the forum. I just finished a survey on the boat we hope to buy. One surprise that came up was discovering the fiberglass mufflers are starting to weep a bit. I assume its standard configuration to have two fiberglass mufflers on each side. They are behind cabinetry in aft cabin. Two in series on the port, two in series starboard. The one closest to the engine on the port side is weeping enough to see, feel, and notice residue from dripping on inside of hull. The starboard side is only barely starting, hard to see, no drip residue. The second muffler in series on both sides seem totally fine so far.

This GB has the 3116TA engines, 3300-ish hours. The forward part of the exhaust system was replaced by the current owner when they purchased it and is very nice. I think the hoses that go aft to the mufflers are all original. FWIW, they look to be in great shape.

Replacing these looks like quite a job and probably not one I would want to do, or do alone. Has anyone here been through this with their GB? I would love any advice, experience, thoughts, cost experience, or questions to ask as I navigate addressing this. The surveyor seems to indicate it is something to address during my ownership, but is not urgent. He has lots of GB experience and says its pretty common to see with a boat of this age in salt water of the PNW.

I looked for threads on this before and didn't uncover any that hit what I was looking for. If missed any don't hesitate to tell me.

Thanks in advance!

 

[Comodave]

Is there any room at all around the muffler? If there is then you may be able to glass it in place.

 

[inquisitivej]

Is there any room at all around the muffler? If there is then you may be able to glass it in place.

Interesting. I would think replacement would be better for performance of the muffler going foward. I assume there are some baffles inside the mufflers that would also be deteriorating which glassing the exterior would not address. I want to do my best to keep this boat in the best condition I can and avoid short term fixes, at least on core systems like engines (and their exhaust). Would love counterpoints to this view or additional info on those mufflers.

 

[Jeff F]

I wouldn't assume that evidence of drips means bad muffler(s). Consider cases where water may have come in from above and dripped down. Or maybe I misunderstood your description.

 

[inquisitivej]

The weeping appears to be dispersed not a single hole or something. At least that’s what I understood from surveyor. 30 years of hot corrosive water supposedly dissolves the resin from the fiberglass and water slowly starts penetrating the fiber. So I’m told.

 

[koliver]

See what you can find for replacements at popular sites like this one: Vetus LP50 Exhaust System Mainfold Silver | Waveinn
A repair just sounds wrong.

 

[inquisitivej]

Thanks for that. Yeah, I had never thought about repairing it, i just figured replacement was the only option. So its been good for me to think about that option. However, replacement is still where my head is at.

Any other GB owners done this project? Would love to hear about it.

 

[RT Firefly]

Greetings,
Welcome aboard. Do you NEED 2 mufflers. Might you simply remove the leakers, extend the hoses and carry on...?
Another alternative is yank the 2 and replace with one new on each side.

 

[inquisitivej]

Interesting thought. I just figured they put two in there for a reason and that I should keep it that way. I don't know why they put two inline or if they are even the same.

I'm new to boating, any GB'ers have experience with this?

 

[Delta Riverat]

Yeah, kinda weird. Usually only one water lift muffler. Perhaps the guy before wanted a really quiet boat?

 

[inquisitivej]

These are original from factory. They are in the aft cabin not engine room.

 

[luna]

The weeping appears to be dispersed not a single hole or something. At least that’s what I understood from surveyor. 30 years of hot corrosive water supposedly dissolves the resin from the fiberglass and water slowly starts penetrating the fiber. So I’m told.

I have never heard of this before.
Has anyone else experienced this kind of heat/exhaust gas degradation of the fibreglass exhaust system components?

I run a pair of 1993 Cat 3408s which are almost 3 times the displacement of your 3116 engines and expel out the exhaust, at almost full trot, about 1,500k BTUs an hour.
At 1000 RPM my 8" diameter fibreglass exhaust tubing within 3' of the shower head runs at 140º F. max, and that temperature is at the top of the tube only, simply due to low water flow. At 2000 RPM the same tube, at the same place runs below 100ºF. because there is lots of water flowing out of the shower head. Velocity helps, a lot.

The fibreglass mufflers which are each the size of a large suitcase run below 100º F at all times.
They don't appear too weep a drop after 31 years of being partially submerged at rest and running for about 4000 hours. I don't expect that to change anytime soon.

Now you have made me inquisitive!

 

[inquisitivej]

Very interesting. I don’t have direct experience with the boat so can’t compare temperatures you are talking about. Does that engine model have a turbo? This one does, not sure if that would change things materially with exhaust?

 

[luna]

Yes, it's an 1100 Cubic inch, 65º V8, twin turbo engine that is rated at 800 HP. EGT at 1900 RPM cruise is about 700º F.

 

[inquisitivej]

What boat do you have these in?

 

[luna]

This is not mine, but similar.

https://www.yachtworld.com/yacht/1996-tollycraft-57-pilothouse-motor-yacht-9559245/

 

[lwarden]

I have never heard of leaking mufflers before. I would want to see some up-close pics before making any suggestions or planning replacement. Sounds fishy to me. Fiberglass doesn't degrade like that under just water and exhaust gas.

 

[inquisitivej]

Once I get all the pictures and survey report I will share them. My surveyor worked on lots of Grand Banks in the PNW for 15+ years and knew this was a thing to look for or he wouldn’t have opened up the panels to access them. It’s a thing.

I just don’t know what folks have experienced in replacing them. That’s what I want to know. I’m not the first person to face replacing these things.

 

[Bmarler]

I wonder if they were experimenting with fire retardant resins or something. It’s definitely not normal to see that sort of permeation. Is there any information on who the supplier was?
I have friends with a 36 classic, they go to the rendezvous most years. I’ll ask them if they’ve heard of this.

 

[Fleming]

It's not an unusual setup and it's not unusual to find holes in fiberglass mufflers. I also would not consider it to be a 'oh, I'll get around to it' project because where it can leak water it can leak exhaust gas. I would consider warming them up and looking them over carefully with an infrared camera which might help you see what's going on. It could be as simple as wear in a chafe location. I've seen 1/2" holes in the side of mufflers before that the owner wasn't even aware of because they didn't run at night and were never sleeping back there when it was leaking. I think a fiberglass patch would be fine once you identify if and where exactly it's leaking.

 

[Sax]

I have been through this whole issue with my 1995 GB42 Classic with Cat 3208TAs, 8 inch exhaust with single mufflers installed behind cabinetry. When I bought the boat 10 years ago, my surveyor looked down the exhaust from the stern and saw indications of rust in the exhaust tubes from the wire coils in the tubes. He said I would need to replace the exhaust someday. Like your potential boat, the previous owner picked the low hanging fruit and replaced the exhaust hose from the shower head to the 90 degree fiberglass elbow. The remainder of my exhaust was original.

Here are some thoughts: The leak may be at the hose fittings on the muffler. Best case scenario. Unlike fiberglass elbows, particularly if crush rings are not installed, the exhaust mufflers can take quite a bit of clamping force.

My mufflers have drain fittings for winterization. They may be leaking.

Worst case: The mufflers could in fact be weeping or the hose clamps over tightened and crushed the fiberglass. In that case removal is only option.

I replaced my complete system a year ago by myself. I had a crushed elbow where my exhaust transitioned behind the full tanks. I also found cracking and weeping in locations that are normally difficult to observe such as behind cabinetry and bottoms of exhaust hose. Finding this damage required some disassembly and use of mirrors and cameras to detect. Based on the age of your boat, you may have similar issues.

Now the bad news. In my boat, I couldn’t replace the in-line mufflers if I had wanted to, without starting at the engine exhaust manifold and disassembling the whole exhaust system. My mufflers were good in condition, but were leaking a little from the junction with the exhaust hoses. The rest of the exhaust system needed replaced. My problem, was that in order to replace the complete exhaust system to the stern tubes, I had to get the mufflers out of the way. This required cutting up and later rebuilding some cabinetry.

So to cost. I found someone with a similar boat that was charged $18,000 to replace his whole exhaust system.

I did mine myself, but parts alone were over $5000 for 36 feet of 8 inch hose, new fiberglass elbows, and clamps. I had to remove all the engine room systems (water maker, water heater, Vacuflush, engine synchronizers, fresh water pump, etc) to get room to maneuver the exhaust house into the engine room and behind the fuel tanks. I used straps and chain hoists to laterally slide the 90 lb 12 foot hose sections through the boat and behind bulkheads, cabinets and fuel tanks. Then I had to connect all the bits and pieces together in locations that were difficult to access.

So if you need to replace the mufflers…it could be a project. If you end up going down that road, replace everything at one time.

 

[lwarden]

OP made it sound like the fiberglass structure has porosity, this is very different from holes worn through by sharp thingies rubbing against it, or collapse of an input tube due to overtightening of a hose clamp on hot end with no crush sleeve. I can also see leaks where ends are bonded on happening, but the tubing itself is in most cases, machine wound FRP which is generally not prone to pinholes.
These things aren't rocket science, if there is a defect it usually can be repaired in-place given adequate access.

 

[Sax]

Agree with Iwarden. In my case, the only part of my 29 year old exhaust system that I didn’t need to replace was the mufflers. The key for the OP is to determine the actual source of the leak, determine if and how it can be repaired, and then adjust his offer. If the muffler needs to come out, it can be a huge, expensive project.

 

[JackConnick]

I've been through this with my 1991 36 GBC. I too am surprised you have two mufflers, you might be able to have one longer one made?
Anyway, mine was crushed around the hose attachment to the engine. This is common as the old ones did not have SS crush rings installed - nothing to tighten to other than fiberglass. While it is tempting to tighten that ring to stop the leak, be very careful.
I have a good mechanic that said normally you haul out and pull exhaust from the stern. However what we did was to put in a sewer pipe plug in the outside exhaust outlet, then saw out a 1' chunk of hose. He loosened the other end and was able to slide the old muffler aft and then out. There was about 10" of vertical clearance. We only had to remove some drawer slides.
We had a custom muffler made that fit within that size as well as an 8" long ring. We bought a silicone flexible adapter ring and attached that to the muffler on the outboard end, then to the FG ring and onto the existing exhaust hose. The silicone adapter allows bending to fit it in. Cost for all was about $1800, he did it all in about 3 hours. The muffler was made at National Mufflers (?) in Marysville.
I have seen some additional leaking from the hose to muffler and tightened it last summer. I think the muffler moves around and the joint pens up. I'm considering adding another hanging strap to the joint area to support it better.
We actually had to move the port muffler out of the way to fix a fresh water pipe leak on the other side and used the same technique, only having to buy the silicone adapter.

Trident Marine Hose 270V6000SS | Fisheries Supply

Save More on Your Trident Marine Hose #270V6000SS 6IN BLU VHT SLC HUMP HOSE W/CLAMPS at Fisheries Supply. Excellent Customer Service, Ready to Ship. Marine Supplies Since 1928!

www.fisheriessupply.com

National Marine Exhaust | Marysville, WA

Custom Stainless Steel Marine Exhaust Systems. We live and breathe custom marine exhaust. From individual parts to redesigning entire systems, no one has a better reputation, warranty, or record than National Marine Exhaust, Inc.

www.nationalmarineexhaust.com

Jack

 

[inquisitivej]

lwarden and Jack, thank you! Very helpful posts! I'm now sufficiently concerned how the costs, time, and disruption could unfold. While not what I wanted to hear, its exactly what I was looking for.

The point made about the gasses potentially escaping the muffler if the water can is an interesting one and not something I had conceived of. For the moment the weeping is pretty minimal still and if there are gasses escaping they are likely also very low level and going unnoticed given how the mufflers are behind panels and cabinets. I also can imagine when underway there may not be anyone in that aft cabin to notice low levels of gasses. Everyone forward or on fly bridge enjoying the day.

I think the metal portions of the exhaust system that were replaced might have been done by National Marine Exhaust, I need to find the records on that, sounds familiar. It is very nice work they did in the engine room.

 

[JackConnick]

I think your surveyor had it right. Its probably 3 boat dollars and a pita, but a negotiation point, not a deal breaker. i wouldn't be that concerned with gasses escaping, more a dribble of water into the bilge. The panels by the mufflers are a very tight fit. This is all fairly common.

Jack

 

[inquisitivej]

3 boat dollars! Ha! Nice.

 

[inquisitivej]

We closed on the boat!

 

[Comodave]

We closed on the boat!

Good luck with it.

 

[JP2]

Maybe this might help.
In three GB's over many years, this issue was seen in 2 of them. Did some research and learned that some mufflers came from Centek. However, GB made their own for many years off Centek designs and in custom sizes to fit discharge and space requirements. Centek is great to work with and has records on everything they made IF you can find a serial number on the part. Secondly, there exists "regular resin" and hi-temp resin, which Centek always uses (up to 350F, if I recall correctly). Guess who just used the regular resin. This was confirmed in discussions with the factory. Finally, I believe Centek proucts are "spun wound" (centrifical) lay up while the GB factory was simply linear or standard lay up, resulting in a different strength rating, for whatever that's worth.

I replaced one muffler and while it was a tight fit, it was an easy project in the engine room. Soft mounts were re-used to deal with movement and "torque clamps" for the connections. Crush sleeves are essential and some of our weeping problems were the result of never having been originally installed.

We also used the services of an excellent fiberglass repairman who made patch repairs directly on a muffler, F/G tube extension, and elbows. They looked stronger than the original product and held up over the years with no issues whatsoever. He insisted on using the proper resin, although it was not easy to find. Total expenses on all of this were less than 4 figures, as I recall, but that was more than a few years ago. Never found evidence of problems with the hose runs. Would agree that hauling out for replacement through the stern is the easiest approach for that one.