Author Topic: Exhaust muffler repair (Read 9103 times)

Lyra · « **on:** January 14 2017, 12:31 »

Today I dismantled the mixing elbow for some cleaning. I found some salt crystals at the bottom of the compartment that houses the exhaust muffler so investigated it and noticed that there is some corrosion at the bottom side. I removed the whole unit and see that there is corrosion on the bottom of both sides. Actually it looks like some kind of pitting and I assume that this pitting goes inside between the SS body and the rubber housing and allows water to seep out.
I have the ability to repair this by Argon welding but before I go ahead and try to separate the SS ends from the rubber body is there anything that I should look out for, or is it just removing the two bands and taking it apart?

tiger79 · « **Reply #1 on:** January 14 2017, 12:39 »

Yes, removing the clamps should allow you to separate the end pieces from the rubber tube. But the corrosion is rather extensive, and I'm not sure how easy it will be to effect a lasting repair. Might it be time to consider replacement?

Lyra · « **Reply #2 on:** January 14 2017, 12:55 »

Thanks,

Will open and see.
This pitting is odd. Resembles the type of pitting you have due to galvanic corrosion. Can't understand how this one developed.

Lyra · « **Reply #3 on:** January 14 2017, 13:31 »

OK, took it apart an it really looks bad. Not sure if it is reparable but will give it a try.
I looked at the marinepartseurope.com and these end plates are marked as "out of production" so I assume the whole exhaust int his configuration is no longer manufactured. I still have he option to build them from scratch - these are not complicated parts, but will have to evaluate the economics for this.
Can anybody recommend a replacement muffler in case I have to buy a new one.

tiger79 · « **Reply #4 on:** January 14 2017, 18:09 »

Quote from: Lyra on January 14 2017, 13:31

OK, took it apart an it really looks bad. Not sure if it is reparable but will give it a try.
I looked at the marinepartseurope.com and these end plates are marked as "out of production" so I assume the whole exhaust int his configuration is no longer manufactured. I still have he option to build them from scratch - these are not complicated parts, but will have to evaluate the economics for this.
Can anybody recommend a replacement muffler in case I have to buy a new one.

The same silencer is still available from Volvo Penta, look for part 828064, assuming you have 45mm exhaust hose.

Salty · « **Reply #5 on:** January 14 2017, 18:53 »

Quote from: Lyra on January 14 2017, 13:31

OK, took it apart an it really looks bad. Not sure if it is reparable but will give it a try.
................... I still have he option to build them from scratch - these are not complicated parts, but will have to evaluate the economics for this.
Can anybody recommend a replacement muffler in case I have to buy a new one.

I had the same problem with my old Volvo silencer, I took it to a local stainless fabricator, but I could tell from what he said that a repair was likely to be expensive. So I checked out the alternatives, and in the "Force 4" chandlery catalogue there is a waterlock silencer, something that does exactly the same job as the old Volvo part, but this item (Part No. 830298) costs just £53.95. That's not a lot of money, and was vastly cheaper than the envisaged repair was likely to cost. I bought one and fitted it last September, and so far it's had about eight hours of actual use. It's made entirely of plastic, so there has to be a water supply throughout the time it is in use, but that is no different a requirement from the original system. Am I happy with it - very much so, though it would be nice to have had a few more hours under the belt to be 100% sure. If you want to spend more money you could go for one of the Vetus mufflers. They too are made entirely of plastic, so my guess is that the £98 that they cost is down to the name rather than any arguably better quality. Would I go back to a Volvo silencer? Absolutely no way, as the stainless ends are just corrosion waiting to happen as postings elsewhere this forum will confirm.
PS the silencer I refer to above has plastic ends to which the exhaust hose connects, and those ends are stepped such that three different sizes of exhaust hose are catered for.

PEA-JAY · « **Reply #6 on:** January 15 2017, 09:24 »

I agree stainless steel in hot salty exhaust is prone to galvanic corrosion. I am concerned with just a plastic replacement as I'm afraid it could melt if water flow fails. I have seen Centek Vernalift on ASAP Supplies website. I believe they are worth considering. Regards, Raph.

Salty · « **Reply #7 on:** January 15 2017, 09:46 »

Quote from: PEA-JAY on January 15 2017, 09:24

I agree stainless steel in hot salty exhaust is prone to galvanic corrosion. I am concerned with just a plastic replacement as I'm afraid it could melt if water flow fails. I have seen Centek Vernalift on ASAP Supplies website. I believe they are worth considering. Regards, Raph.

Sorry Pea Jay, but it's not galvanic processes in this case that cause the problem, it's the lack of oxygen in the water that remains within the silencer while your boat is moored up for a lengthy period that is the trouble. Stainless steel and stagnant sea water are a recipe for corrosion, and which is why the bulk of corrosion occurs at the low end of the Volvo exhaust silencers rather than at the high end. Similarly with keel bolts where there is a loss of sealant between the upper flange and the hull, and sea water gets in to the bolt area but not in sufficient quantity to allow the trace of water there to be exchanged and re-oxygenated. It becomes stagnant and the stainless bolts are then attacked. This is why some boats have mild steel bolts where the builders feel that mild steel is better able to withstand the presence of stagnant sea water than stainless.

Symphony · « **Reply #8 on:** January 15 2017, 10:55 »

Yes, it is crevice corrosion rather than galvanic action that corrodes the end plates. Made worse if the boat is unused for long periods with water laying in the bottom.

Lyra · « **Reply #9 on:** January 15 2017, 14:52 »

Thanks for pointing out the plastic option.
I am not in the UK but do have a local Vetus rep. so it will probably be their model.
Looking at the pictures - do these units have to be installed so that their bottom is horizontal or can they be installed on a slope (up to a certain limit). Could not find any installation instructions.

tiger79 · « **Reply #10 on:** January 15 2017, 15:46 »

Vetus Waterlocks should be installed horizontally, and upright.

You can find installation details on the Vetus website here - http://www.vetus.com/documents/all/exhaust-systems.html

Salty · « **Reply #11 on:** January 15 2017, 17:58 »

Quote from: PEA-JAY on January 15 2017, 09:24

..............I am concerned with just a plastic replacement as I'm afraid it could melt if water flow fails. I have seen Centek Vernalift on ASAP Supplies website. I believe they are worth considering. Regards, Raph.

Yes, that Centek stuff looks pretty good, and should give you a little more time between losing your cooling water and realising that your engine was about to be cooked, but I'm guessing it's probably going to cost quite a lot more money than the waterlock silencer I bought. That however, is the beauty of choice, if it suits you then go for it.

Craig · « **Reply #12 on:** January 15 2017, 21:44 »

All the Volvo exhaust systems seem to get pit corrosion in the stainless steel.

On my Bav 38 ( 2010 model) I replaced with a Vetus exhaust system. All plastic, no parts to corrode.

I did have to but another length of rubber exhaust pipe as the Vetus system is slightly shorter than the Volvo system.

From memory the Vetus system cost about $100 Australian ( about 60 DBP) or 70 euros. It also cost about $10.00 for the rubber pipe.

Easy job, just had to undo the hose clamps on either end and reattach.

Craig
"Shirley Valentine"
Gold Coast
Australia

tiger79 · « **Reply #13 on:** January 15 2017, 22:41 »

Quote from: Craig on January 15 2017, 21:44

All the Volvo exhaust systems seem to get pit corrosion in the stainless steel.

I had a Volvo silencer on my old Hallberg-Rassy. I sold the boat when it was 24 years old, and the original-fit Volvo silencer was still fine.

Salty · « **Reply #14 on:** January 15 2017, 22:43 »

The plastic waterlock silencer I purchased from Force 4 chandlery and referred to in an earlier posting above, although a different shape from the old Volvo silencer it was replacing, it fitted into the same space and the existing exhaust hoses coupled directly to it without any need for adjustment. So like Craig's posting above, it was an easy, arguably easier job to fit because nothing needed to be modified. It is located under the port aft cabin bunk where it fits with plenty of room to spare.

Lyra · « **Reply #15 on:** January 16 2017, 08:10 »

Thanks to all comments.
Will probably purchase the Vetus silencer this week - it is in stock with the local dealer. Price here is about 50% higher than in Europe/UK but that's life (considering shipping and tax it will not be much cheaper buying online).

aquapore · « **Reply #16 on:** January 22 2017, 10:19 »

I had the same problem with my Bav 41. Corrosion beyond mere pitting.

I was quoted more than $500 (aus) from local Volvo dealer.

My solution was to laminate the inside of each dished end and spigots with light woven fabric (about 3 layers with epoxy) and a further layer (thin) on the outside lip of the dished ends and spigots.

I then re-assembled the muffler and poured in about a cup of polyurethane liquid membrane that was originally used for sealing bathroom floors. I then rotated the assembly in all axes to coat the entire inside before draining the excess. I also painted the outside the assembly with the same material - cosmetic and protection of the connecting surfaces.

The urethane was supplied by Tremco under the name of Vulchem. I think any high solids liquid applied poly urethane membrane would work.

I re-installed the muffler. That was 3 years ago. All good so far.

Regards

Aquapore

.

jonrarit · « **Reply #17 on:** January 23 2017, 15:50 »

I had this problem last year on our B36 (2006) ...... my solution was to completely clean up the area then cover the offending are both inside and outside with epoxy for stainless steel from Rs Components (Part no 691-189)

As the entire inside of the silencer end cap now has a layer of epoxy, there is no longer sea water in contact with the stainless steel

jonathan

gam1961 · « **Reply #18 on:** January 24 2017, 23:13 »

My B30 muffler was rotten. Replaced it with a plastic one from Vetus. Will probably out live the engine!

http://www.vetus-shop.com/product_info.php?products_id=2349&osCsid=813618f214d4dbbf7cd6545e49f81949

sailprincess · « **Reply #19 on:** June 21 2017, 21:18 »

We had the same problem on our Bav 40 (2002). The pitting was pretty bad. We just took it in and had new endcaps molded from fiberglass. Going to install it and try it out today or tomorrow. Pics attached!

Salty · « **Reply #20 on:** June 21 2017, 23:23 »

It looks a first class job SailPrincess, and I don't want to detract from that in any way except to say that it probably cost you rather more than my £53.95 plastic silencer which, by the way, now has about forty hours of use under its belt. However, just to be sure, I did fit an exhaust temperature monitor which cost rather more than the muffler at a little under £100, but on a recent trip across the Irish Sea where adverse winds meant having to motor across, and back, the monitor noted that the exhaust temperature did not exceed about 26C, and that gives me great confidence that the plastic muffler will out last the old Volvo system.

sailprincess · « **Reply #21 on:** June 21 2017, 23:35 »

Thanks salty! We've installed it now and ran the engine for a bit. All seems great! This was a $200 USD fix, so not too bad and in theory should last a very long time. Those stainless ones aren't the best design, that is for sure!

solar · « **Reply #22 on:** June 22 2017, 12:31 »

Quote from: sailprincess on June 21 2017, 21:18

We had the same problem on our Bav 40 (2002). The pitting was pretty bad. We just took it in and had new endcaps molded from fiberglass. Going to install it and try it out today or tomorrow. Pics attached!

Looks great!
Would like to learn how to do this?
Mine is still fine but you really can't tell when it goes South...

Author Topic: Exhaust muffler repair (Read 9103 times)

solar