Hot Section Rebuild

[rigspelt]

My view, and I could be corrected, is that if the engine cranks and cranks without firing and the seawater throughull is open, then the water pump keeps dumping water into the waterlock muffler, filling it up because when the engine is not running there is no exhaust gas to push it out the stern. Eventually the water backs up into the hot stack and then into the manifold, and trickles backwards into a cylinder through an open valve, displacing air inside the engine which I guess bubbles up through the hot stack as water comes down. Am I right?

[joe_db]

Much more exhaust gas comes out of the engine when running than air does when it is just an air pump and not firing. Some systems will not clear the water with just air.

On another note - in another thread Tom from Indigo had a stainless exhaust corrode to pieces pretty quickly. I was about to order stainless when I read that. Then I decided bronze would be good and it seems there is no such thing as bronze nipples - only brass

So is it back to black iron

[Crash]

Second attempt

Missed the rain this afternoon but I completed setting up the second attempt at installing the hot section but this time it's somewhat a combination of all the comments I received from the first install.

All I did this time was to extend the mixer 6" down with black iron and screwed on a 45 degree elbow. This actually put the mixer in a better angle to the water lift (thanks Shawn). The wire reinforced exhaust hose was still a #*&%@ but at least I had a heat gun to help out.

I fired up the engine (kick over the first time again with moderate choke, ) and was working like a charm. Water and exhaust discharge was much better than with the original set up and still sounding like a race engine. Going to finish the project with heat wrap soon.

Sorry folks I'm really stoked right now! Oh sorry for the over sized photo...

[sastanley]

Crash...looks good to me!

That blue striped exhaust hose should handle the heat no problem...just check it (without burning yourself) to make sure it is not distorted after some run time...I found that on all soft connections (i.e., you needed a heat gun to bend it) that they leak as it warms up...expect to re-tighten the hose clamps around the system.

Every inch in the hot stack I think gives you a little more wiggle room & keeps water away from the cylinders...Also, expect to need full choke to start her...it is not uncommon...if you are old enough like me that you've driven a car with manual choke, they never needed it full on, but these updraft carbs usually need full choke to start..

[Crash]

Shawn, yup that blue striped hose is the wire reinforced exhaust hose, brand spanking new. With this version I was able to cut off another 12" of hose and even though in the picture the hose looks curved (to the left) it's actually curved slightly down ward to the water lift.

Yes, checking for distortion (and kinks)in the hoses is a practice I've already had since my first boat. Thanks for the reminder, as it's always a good thing. As I removed the old exhaust hose and inspected it for the possibility of reusing I noticed the interior of the hose was severely "bubbled" to the point it restricted (in my guess) more than half it's capacity. I plan to replace the rest of the hose from the water lift to the stern soon.

Thanks to everyone here on the forum I got a new hot section and a wifey that's a little excited the boats back in order!

[HOTFLASH]

Yet another consideration

This is a terrific thread! I thought I read somewhere that there should be 2 feet of metal pipe post the point of mixing gases and cooling water, before the muffler--to allow for some space/time for the gases to cool a bit before hitting the fiberglass waterlift, or any hose. I think the waterlift manufacturer recommends that.

[rigspelt]

I was a little uneasy about that hose too. Will it tolerate the heat? A section of hose connecting hot stack to waterlift muffler reduces engine vibration problems at that joint, but I imagine the gas is pretty hot at the water injection point and for several inches past that point.

[Hiker_00]

My boat came with an anti-sphone loop between the manifold and injection point. It's mounted high above the engine compartment and makes me feel good.

I had water backing up while heeling that went away after replacing the worn out hot section in the same configuration here. It's gone through the first summer season and never a worry.

Tim

[HOTFLASH]

Hose OK downstream of 2 feet of pipe post mixing.

RIGSPELT,
After the 2 feet, hose is OK to connect into the waterlift--to address the vibration issue.
Mary

[Crash]

The sum of all the hot section parts including the mixer equals to 25 1/4" total. The new exhaust hose is actually 8" shorter than the original hose and after letting the engine warm up the hose was only warm to the touch at most. I'll know more once I get her out of the marina under full load. The hose is rated for this application so I'm more then confident it'll handle the heat. I'm watching to see if I need to install an anti-siphon in the water loop since the original didn't come with one and now she's performing better than when I purchased her. With better water flow I feel better knowing the hose will be a lot cooler now as I can see the discharge at the stern is 3x's better.

[jpian0923]

I hate to be an alarmist but with the new water injection point you have alot more hot section. I would double wrap it. Fire on a boat is much more dangerous than water in a cylinder. I'm a pessimist, but...safety first!

[edwardc]

I hate to be an alarmist but with the new water injection point you have alot more hot section. I would double wrap it. Fire on a boat is much more dangerous than water in a cylinder. I'm a pessimist, but...safety first!

When I did mine, I overlapped the wrapping by a full 50% instead of the tiny amount recommended in the instructions. This resulted in a double-thickness of the wrapping everywhere, consuming the entire roll of wrapping material on this one stack.

[Crash]

Jim,
The MMI exhaust wrap was long enough to get double wrappings on the top parts of the hot section as Edwardc pointed out. I have to admit though I did lower the first pipe by 2 inches so the space at the top (to the bottom of the deck) increased from 2 inches to 4 inches. On the trial run the deck warmed up to the point I was ready and armed with a fire extinguisher...just in case. So with 4 inches of clearance to the decking and double wrapped hot section I'm good to go!

Okay next repair issue....... (remote radio controls now works!)

Crash...(no burning)

[tartansailboat]

another myster part

I have a 1972 T30 with the Moyer SS water lift muffler. The PO had a leaking copper standpipe which was replaced by a "butcher" right after the survey. He installed a Volvo water lift muffler which never fit right. When I had the mast pulled, I had the yard install the Moyer SS water lift muffler, the custom standpipe was not available at the time. Unit ran super for three years.

First sail of this season, engine sounded like it was lugging, not revving up properly, low power, starting to overheat. Limped back to the dock and saw that the exhaust line from the output of the water lift had blown off, filling up the bilge, temperature immediately lowered. I suspect that there is a blockage after the water lift muffler creating overpressure, hence the engine symptoms and finally blowing off the exhaust line. With the exhaust line off, plenty of water coming out of the water lift muffler so I don't think the problem is with the muffler or the engine, exhaust, etc.

But between the water lift muffler and the thru hull ( a short distance since both the engine and thru hull are mid ships) there is a black plastic part, double cone shaped like two ice cream cones stuck together at the wide part. It is about 10 inches long and about 4 inches in diameter. Any idea what this is and if it is blocked, can I remove it and just run the exhaust to the thru hull.

I recall a nice explanation about the difference between the stand pipe and the water lift muffler, is this part meant for standpipes and not needed for water lifts?? I will try to get photos tomorrow.

Thanks in advance. Sorry for rambling.

[67c&ccorv]

I have a 1972 T30 with the Moyer SS water lift muffler. The PO had a leaking copper standpipe which was replaced by a "butcher" right after the survey. He installed a Volvo water lift muffler which never fit right. When I had the mast pulled, I had the yard install the Moyer SS water lift muffler, the custom standpipe was not available at the time. Unit ran super for three years.

First sail of this season, engine sounded like it was lugging, not revving up properly, low power, starting to overheat. Limped back to the dock and saw that the exhaust line from the output of the water lift had blown off, filling up the bilge, temperature immediately lowered. I suspect that there is a blockage after the water lift muffler creating overpressure, hence the engine symptoms and finally blowing off the exhaust line. With the exhaust line off, plenty of water coming out of the water lift muffler so I don't think the problem is with the muffler or the engine, exhaust, etc.

But between the water lift muffler and the thru hull ( a short distance since both the engine and thru hull are mid ships) there is a black plastic part, double cone shaped like two ice cream cones stuck together at the wide part. It is about 10 inches long and about 4 inches in diameter. Any idea what this is and if it is blocked, can I remove it and just run the exhaust to the thru hull.

I recall a nice explanation about the difference between the stand pipe and the water lift muffler, is this part meant for standpipes and not needed for water lifts?? I will try to get photos tomorrow.

Thanks in advance. Sorry for rambling.

Sounds like you have muffler installed in that section - is it possible the muffler has become blocked?

Rodents/birds/mud wasps love to build nests in these small openings...you need to check it out.

Cheers!