Aqualift muffler

Jeff Kaplan · October 28, 2022, 04:13:33 PM

I post this question to all who have replaced the aqualift muffler. Last spring I had to have a mechanic on board and he mentioned that some exhaust work should be done in the near future. I asked him if it was the muffler and he said yes. The boat is an '86, M25, and it is probably the original, however, the engine runs like a top and there is no leaking out of the muffler. The removal looks pretty straight forward, 4 screws in the corners, remove the inlet hose from the riser and remove the output hose. Question is, how hard is it to remove and where did you get a new one. I saw what looks like the original on Catalina Direct, no price listed. Also, if there is no leaking, should I undertake this project. All replies greatly appreciated. As the boat is now on the hard, this will be a spring project. Thanks in advance...Jeff

KWKloeber · October 28, 2022, 05:09:12 PM

I'd question how the mechanic was clairvoyant and knew that "in the future" a muffler needed to be replaced if it isn't damaged or leaking at the bottom seam (notorious for that) or one/both of the tubes crushed (also prevalent if clamps are too tight/no hump hose.) And if it was, then he should have shown you that and recommended doing it right then (exhaust can kill.)

The OEM Aqualift is NLA, and it was prone to failures at the locations I mention.
CD has contacted with Centek to make CD's "near OEM size" muffler which is excellent quality at a CD price (you can't buy it direct from Centek.)

You might find what Bill did to be interesting so long as you plan to change out the Aqualift.
https://c34.org/wiki/index.php?title=Diesel_Engine#Exhaust_System

Ron Hill · October 29, 2022, 12:14:31 PM

Jeff : I agree with Ken. There are only a few reasons that you need to replace the Aqua Lift muffler. Leaking in the edges or hose connections!! Crushed/broken inlet or outlet tubes on the muffler. Loss of the seal between the top and bottom pieces of the muffler body.
Otherwise if all is OK and you have a hump hose (which reduces stress on the molded muffler inlet) - I'd just leave the muffler alone until there is some leakage!! If it ain't broke don't try to fix or replace it!!

Also check to make sure that you have a nylon (not a wire reinforced) hose from the anti syphon valve to the nipple on the exhaust riser. This reduces stress on that nipple's weld!!

A few thought

Stu Jackson · October 30, 2022, 11:16:36 AM

My Feb 2016 Tech Note

https://c34.org/mainsheet/pdf/2016/Muffler%20&%20Exhaust%20Riser%20Replacement.pdf

WTunnessen · November 01, 2022, 01:33:57 PM

Aqualift mufflers can be repaired and rebuilt if needed. I rebuilt mine fairly recently and it was not too difficult. There is info on the Forum on how to do this.

When they fail, its usually at the in and out take tubes/flanges where the hoses connect.

Usually the in-take tube goes first, especially if there is not a silicon hump hose between the metal exhaust riser pipe and the Aqualift. Leaks, cracks, or damaged looking in/out take tubes would be signs of a failing Aqualift. Remove the hoses and inspect the tubes would be a good first start. But if its not leaking, then its probably fine.

The drain tap also can rust out. Catalina Direct sells replacements.

Stu Jackson · November 01, 2022, 01:35:59 PM

Walt's right.

Mufflers 101 - What's in Your Muffler?

http://c34.org/bbs/index.php/topic,6728.0.html

Jeff Kaplan · November 01, 2022, 03:50:39 PM

Thanks for the responses. There is no leaking from anywhere I could see. I replaced 18' of the discharge years ago, but never touched the intake. FWIW, there is just a straight piece of rubber tubing from riser to inlet, no hump hose. Its been running great for all these years, there is a saying in the trucking world, if it ain't broke, don't fix it. So until a situation arises, I'll deal with it then. I do very little motoring, just out of the harbor and back in, unless no wind. Maybe put on 50 hrs a year, if that. Thanks again..Jeff

Ron Hill · November 01, 2022, 04:33:18 PM

Guys : You can go to an auto parts store and get a new butterfly muffler drain valve. No need to go to Catalina $$$ Direct!!

A thought

Jeff Kaplan · November 01, 2022, 05:30:57 PM

When I posted this, I didn't know if there was a need to replace due to age, or of course, leakage. I'm glad I asked, it'l stay the way it is for now, hope I didn't just curse myself. I should also ask, if it becomes defective under motor, what will I hear that would alert me, I don't see the engine over heating? Jeff

KWKloeber · November 01, 2022, 08:11:09 PM

You will see exhaust water leaking out the bottom seam, ending up in the bilge. Not fatal as far as motoring goes but obviously needs to be fixed. If one of the tubes gets crushed you may find exhaust gas leaking out.
OBVIOUSLY that's critical.

Stu Jackson · November 01, 2022, 09:11:29 PM

Quote from: Jeff Kaplan on November 01, 2022, 05:30:57 PM
When I posted this, I didn't know if there was a need to replace due to age, or of course, leakage. I'm glad I asked, it'l stay the way it is for now, hope I didn't just curse myself. I should also ask, if it becomes defective under motor, what will I hear that would alert me, I don't see the engine over heating? Jeff

Jeff, I suggest you think about what the function of the muffler actually is and what goes into it and leaves it.

While "muffler" to most of us means "noise suppressor", it does perform that function compared to dry exhaust stacks on boats.

Two things go in: hot exhaust gases from the engine and warm raw water after the heat exchanger (HX). These two mix at the nipple under the head sink and both go down into the muffler.

The water sits in the bottom of the muffler until there is enough exhaust gas pressure to burp a bunch of water and gas out via the 17 foot long exhaust hose to the transom. The mixture is "cool enough" by then but still plenty hot.

If the inlet of the muffler lets go, you'd get a mix of hot water and exhaust gas on a pretty steady basis. If the exhaust port goes (rare) you'd get the same stuff only in burps. Neither one is good.

Every single recommendation to keep your muffler healthy SINCE 1987 (!!!) has been to remove the old stiff black inlet hose and replace it with hump hose.

Your boat, your choice.

Jeff Kaplan · November 02, 2022, 08:37:39 AM

Thanks Stu, I'll order a hump hose and install in the spring. Thanks for all the responses, muchly appreciated...Jeff

Dave Spencer · November 02, 2022, 02:56:08 PM

Jeff,
The hump hose installation is relatively easy. Here's a link to detailed instructions with pictures. (full disclosure... I wrote it)
https://c34.org/bbs/index.php/topic,6878.msg45884.html#msg45884

I'm sure you"ll have no difficulty.

Ron Hill · November 02, 2022, 05:10:49 PM

Guys & Jeff : Stu made a great post which summarized many posts on this Message Board and the many articles articles in the Mainsheet tech notes.

A thought

Jeff Kaplan · November 02, 2022, 05:17:21 PM

David, thank you so much for that post, and, I have a dremel. The pictures speak a million words, it was good seeing exactly what the riser and muffler look like with out the hose. I will need a 6" hose. I'm thinking I might mix up some west with some silica and apply it all around the inlet tube for added support, let it dry and install the hump hose. Spring project, she's up on stands and covered for the winter. Now come leaf raking and getting ready for winter, but today 11/2, it was 72* in Boston, should be in the low 50's. Thanks again to all...Jeff