Paul,
I have never had that blew but reading your post makes me wonder. If you have one that you can measure down into the tubes and get the length of each. From the top of the tube to the bottom down in the box. I am thinking that one tube is shorter then the other and maybe it was hooked up backwards. I did not see the drain petcock in the picture. That should be facing the rear of the boat, As ours is. If one tube is shorter and hooked up backwards it could create more back pressure I am guessing. Let me know what you find on the tube lengths.

I just read on the Catalina Direct web site that the outlet tube extends to the bottom of the box and inlet does not, Could the first one been hooked up wrong and you followed suit hooking up the new one the same way? Just a thought.

Here's what's inside: [url]http://c34.org/bbs/index.php/topic,6728.0[/url]

Paul
I had a new muffler made by a company in Bellimgham ,price was just over 100$ and they did a better job then Catalina and it fit perfect

My guess is that you have too much back pressure. Some part of the exhaust after the water lift muffler is blocked. The water lift muffler works on the same principal as a water pipe.... Is there a brass check valve in the hose? They are known to fail. Try taking a garden hose and sealing it into the the exhaust end closest to the muffler. Turn on the water, there should be no back pressure, and water should flow out of the stern exhaust, the water may wash out any blockage. Just an idea. :)

Hi Paul,

Is it possible the PO installed a gate valve or ball valve on the through hull fitting for the exhaust? If so, even though it may be open it may be partially plugged. The exhaust hose on our 1989 model exits the top of the aqua lift and travels up to just under the combing between the outboard wall of the port side lazarette and the hull then aft to the transom and down to the through hull fitting, exiting just under the transom. Hope this helps.

Paul,
I'm curious, is the boat in the water or on the hard? Also note that the pic's Stu led you to show that the screws that tie the water-lift down, go through the flange (top to bottom). This is how mine is secured on my boat and was the same with the Catalina 30 I had. In the pictures you included of the new aqualift it appears the four holes (original) are epoxied in? The test date on the bottom makes me wonder if this is a salvaged water-lift? Perhaps this was a problem to start with?

The reason I'm asking if the boat is in the water is, on my 30' when I would throttle up, the stern would push down into the water when making way, thus making the exhaust outlet also under water. The temperature would rise. My thought was that this caused back-pressure.200-300 RPM would make a difference. No science here just an observation.

Paul,
It was my C30 that had the Check valve in it, but my understanding is that some think it will help water back flow to the engine. This was a common issue with the early C30. Have you tried taking a plumbers snake and working it up through the exhaust. You could have a nest or something in there especially if the boat sat on the hard for a while.

Your first failure seems to have been caused by excessive heat in the aqua-lift caused by restricted injected water (pinched hose) into the riser. Might have been the reason for the epoxy repair in the first place. Exhaust sounds are both muffled by the aqua-lift AND the exhaust gasses are cooled by injected water so that components downstream of the riser don't melt.

Your second failure might be heat related as well. When you throttled up, a seam weakened by heat would give up at that point due increased air volume and thus pressure. [B]You should systematically verify that sufficient water is being injected into the riser, that the riser injection point is not restricted, and that the entire wet-exhaust hose is not inhibiting flow.[/B]

Finally, a down-dip in the wet exhaust hose to the point where it collects water is not ideal as this would be a place for all kinds of nasty things to happen. Ideally, you should have an up-slope reaching well above the waterline and then only down-slope immediately at the stern.

Paul, a few months ago I was fortunate enough to purchase a slightly used muffler from another sailor over on co.com for the price of shipping. Nice guy. Anyway, it was sitting in my garage (awaiting install since the inlet port on my 26 year old muffler is pretty well shot), so I took these pictures.

1. The holes go through the flange. I haven't looked at the one in my boat, but I'm pretty sure they do, too, since that's how Ron Hill wrote it up in his muffler replacement article in Mainsheet magazine, probably also on our C34 Tech wiki, but I'm not sure about that. If you look UNDERNEATH the muffler, as long as the hole don't impinge on the BODY of the muffler, they're just for hold-downs using the flange.

2. My earlier reads on your issue, due primarily to having two blow up on you is EITHER (a) you have a restriction in the exhaust line, whether it's a check valve or a dip in the line; [B][U]and/or[/U][/B] (b) you may have installed the inlet and outlet backwards. The higher one is the INLET, the lower one closer to the drain cock is the outlet.

This muffler has the "tested" written on the back, too. It is an OEM factory muffler.

Our exhaust outlet goes underwater when we rev up the engine at higher throttle. I have had no issues with this in 15 years. Nor did the PO who owned the boat for its first 12 years.

Well Paul. If you can blow into the hose and push water out the back of the boat with your breath. I am stumped then.

I completely agree that having the exhaust outlet under the hull go under water by a few inches is an insignificant factor. The additional hydrostatic pressure created by submerging the outlet 3 inches under the water surface is about 0.12 PSI.

I'd suggest making the investment of pulling the exhaust hose off the boat, stretch it out (if possible), and look through it. Alternatively, pull the exhaust hose and run a water hose with the water running through it (to stiffen the hose), making sure the entire diameter of the exhaust hose is clear. When you go to re-install it, route it so that there's a continuous up-slope from the aqua-lift to well above water line (to prevent following seas from making it back to your engine) and from that point a continuous down-slope to exhaust pipe. No sharp bends.

Testing water injection is more art than science as I don't have flow rates. Use your best judgement. Again, make sure the injection point in your riser is clear (insert a screw driver into the injection point) as this is a common place for corrosion to inhibit flow. Assemble your complete system, start your engine and check your exhaust pipe at the stern. You should hear a "slosh....gurgle.....slosh" . At idle, not much water will be flowing with [B]each slosh[/B], but some and it should be slightly warm. Throttle up. More slosh than gurgle, more water, still slightly warm.

Finally, if you do suspect low water flow, then with a cold engine disconnect the injection point, direct the hose into a 1 gallon container such as an antifreeze jug. Start the engine, idle only, exactly 15 seconds, shut down. From winterizing my engine, it seems like that gallon container would be maybe half full. I've only winterized once, so other owners might have a better feel of the flow rate of the raw water pump at idle for 15 seconds. [COLOR="Red"][B]Don't operate your engine for too long like this as you're not cooling the exhaust with the injector hose disconnected.[/B][/COLOR]

Paul, First I will apologise, but it just have to comment on your last statement.
But there is nothing better than getting intimate with the one you love. :D

Paul,
Many years ago I went to a diesel seminar at a local W/U distributor (Hansen Marine), and one of the things the instructor mentioned was exactly what you are looking for. He said that a cooling system which is working properly will push about 10 gallons of water thru it per minute, at 3000 RPM. I can't remember if it was for the M25 or the M25XP, but they should both be very similar:
[URL]http://www.c36ia.com/node/294[/URL]
Once you get things assembled, now at least you have a benchmark. Hope this helps.

[QUOTE=plebel;21713]

Meanwhile I'm waiting for the bright idea bulb to come on with SOMETHING to attach to the exhaust hose so I can pull it back through. Normally you would attach the NEW hose that you're replacing. But I'm not replacing it. I'm afraid that attaching anything smaller will not force the hose to line up with the holes in the walls, esp behind the lazarette... and just leave it stuck.

Any creative ideas will be rewarded with my great admiration![/QUOTE]

You really need two people. Our experience was that the "tag line" method probably wouldn't have worked.

Pictures here:

[url]http://c34.org/bbs/index.php/topic,6760.msg45301.html#msg45301[/url]

Not so much different than yours.

I agree, based on my experience on my 30 2 or 3 people working pushing and pulling a few inches at a time..... no real fun but it works. The rubber on the sticks to everything making it impossible to just slide it through.

Nothing like 5200 "the Devils" for a permanent seal.
Are you able to get the kink out of the hose?

So THAT'S what the inside looks like! Another thing you could use is thickened epoxy. When you drill new holes for the screws, make sure you only drill thru the edge of the flange, and not thru the cavity. As you now know, the screws are only to hold the muffler in place on top of the base, and not to hold it together. Good find for the cause of the blown mufflers!

Interesting to read your story Paul, your face seems to pop up on many adventures! Just a point of interest, in my last boat, with a Yanmar J3HJ engine, I put a thru hull wood plug in the exhaust outlet for a winter. The following spring I forgot to remove it. It was a bit hard to start, but when it did it blew the plug clear across to the next dock. The hoses , engine and waterlift continued to operate normally. You must have developed alot of pressure in that thing to blow it apart!
Talk with you guys next successful story solved.
Gary

Just a thought and agreement with what Tom Soko suggested. You can use heat to soften 5200 and where this is the escape for the exhaust and the ability of pressure building, I would go for the thickened epoxy. use a good measure of it on the flange where you would/will drill/re-drill your holes.

LOL....Good Luck and hope you can be done with this project.

[QUOTE=plebel;21801]Dang I didn't think of that. Too late. I just sealed it with 5200 today. I already had a tube of it. But I'm still planning to seal the seam edges again with fiberglass, and then [U]fasten it[/U] with screws to the plywood base. Hopefully it'll hold. If not, I'll just become the muffler expert.:rolleyes:[/QUOTE]

Don't over think it. Since you've cleared the block on the exhaust hose, which many of us suspected was your culprit, just take it slow and go from there. I think you'll be just fine.