Rusted through exhaust

[BrentS]

Hi all, I have a 78 30' Catalina with an A4 that was rebuilt in 2006 by the previous owner. I've had her for 2 years. She has always run very well until this happened:

she wouldn't reach RPM and and then died. While trouble shooting, during start attempts, I found that the water was coming out the exhaust pipe from the engine. Consequently water was back flowing into the cylinders. I have attached pictures and you will see how the exhaust shows a much darker color on the insulation closer to the engine. It is here that water was coming out.

Am I correct in assuming that the exhaust rusted through? I am new to A4 and only have a basic idea of engine mechanics. To complicate things my boat is in Mexico and I live in New Mexico. So right now she's in the water in her slip and I'm 9 hours away.

I did get the cylinders dried out and put plenty of WD40 in them before locking her up.

Moyer Marine, send me a parts list so I can get her fixed!

[ndutton]

It is impossible to be certain from the pictures but I think your water incursion may have been a result of a hard starting episode with the raw water intake valve open rather than caused by the exhaust. With that in mind, please consider the following:

1. The water lift muffler is likely full of water and must be drained before any future starting attempts. With it full the exhaust backpressure will work against starting attempts.
2. There is no downside to replacing the hot section of the exhaust. It will need to be done sooner or later, why not now? It is all part of making your boat your own.
3. Why did the engine die in the first place? That will need to be resolved and I repeat, I don't think it was because of the exhaust.
4. Is there an anti-siphon loop in the water injection line to the exhaust? It is usually found up high next to the galley sink on the Catalina 30 and is a critical feature on the Catalina 30 exhaust.
5. Did you close the raw water intake valve before leaving the boat? I hope so.

Here is a thread that covers a Catalina 30 exhaust system pretty well:
https://www.moyermarineforum.com/for...ead.php?t=9903

[BrentS]

It always started just fine. Earlier in the day as we were heading out, she wouldnt reach RPM. When she died I was moving in the cove preparing to drop anchor.

I wouldn't be too worried if my mechanic would get back to me, but it's been three weeks and he hasn't responded to my texts, and being so far away I'm losing sleep over this.

Originally Posted by ndutton

It is impossible to be certain from the pictures but I think your water incursion may have been a result of a hard starting episode with the raw water intake valve open rather than caused by the exhaust. With that in mind, please consider the following:

1. The water lift muffler is likely full of water and must be drained before any future starting attempts. With it full the exhaust backpressure will work against starting attempts.
2. There is no downside to replacing the hot section of the exhaust. It will need to be done sooner or later, why not now? It is all part of making your boat your own.
3. Why did the engine die in the first place? That will need to be resolved and I repeat, I don't think it was because of the exhaust.
4. Is there an anti-siphon loop in the water injection line to the exhaust? It is usually found up high next to the galley sink on the Catalina 30 and is a critical feature on the Catalina 30 exhaust.
5. Did you close the raw water intake valve before leaving the boat? I hope so.

Here is a thread that covers a Catalina 30 exhaust system pretty well:
https://www.moyermarineforum.com/for...ead.php?t=9903

[joe_db]

Most A4s have iron exhausts. They rust out and need replacing every few years, the exact number being variable depending on use and salinity. I seem to get about 4-5 years out of my hot sections.
That is issue 1.
Issue 2 is rusting out should neither get water in the engine nor make it quit. The usual result is either exhaust in the boat or exhaust and water in the boat. If rusting puts water in the engine there is something very wrong somewhere!
See the photo.
The other thing that can happen is a leak in the engine or exhaust manifold that is dumping water into the exhaust and making a dry section wet.

[BrentS]

No sir, the water is coming out from the first elbow as the exhaust exits the engine.

Originally Posted by joe_db

Most A4s have iron exhausts. They rust out and need replacing every few years, the exact number being variable depending on use and salinity. I seem to get about 4-5 years out of my hot sections.
That is issue 1.
Issue 2 is rusting out should neither get water in the engine nor make it quit. The usual result is either exhaust in the boat or exhaust and water in the boat. If rusting puts water in the engine there is something very wrong somewhere!
See the photo.
The other thing that can happen is a leak in the engine or exhaust manifold that is dumping water into the exhaust and making a dry section wet.

[Al Schober]

Brent,
Water/exhaust is not supposed to come out through the exhaust pipe. You're going to have to unwrap that whole mucket and see what's there. I really suspect you're going to find a broken pipe.
Part 2 of the puzzle is why you're getting water there. Could be the water lift is full (drain it). Could be that the water injection nozzle is sending water back toward the engine (not good). Could be a bad nozzle or a bad installation. Certainly can't tell with all the wrapping in place.
Would also suggest you don't need a mechanic, you need a plumber!

[joe_db]

OK - do this test:
Take the water injection hose off the exhaust and drain out the water lift. Run the engine *briefly*. The cooling water will be going in the bilge and the exhaust system will be uncooled, so this is like 30 seconds or LESS.
If water still comes out of the exhaust, it is coming from the engine end. This will indicate a block or manifold issue.

[joe_db]

You also can just take the exhaust off and run the engine briefly. VERY briefly. It needs to come off anyway.
I had an A4 that leaked water into the exhaust somehow and shot a fair amount of water into what should have been dry gasses exiting the manifold. The first effect that had was rusting out the iron pipe in the "dry" part and it made the engine prone to flooding as well.

[edwardc]

Your water injection point looks too high on the exhaust. It should be a minimum of 4 inches lower than the lowest part of the high loop coming out of the engine. Any buildup or blockage below the injection can cause backspray to go "over the top" and drain back into the manifold.

[sastanley]

Ed, Agreed..Brent's looks similar to the original C-30 design. However..the limitation is the height of the galley, directly above the motor. If we drop the injection point, now we are suddenly too close to the water lift muffler, which is right under the sink.
If you dig thru the long thread Neil posted, we have been able to remedy the problem a little bit with a short upside down "U" which gives us 3 or 4 inches. The original came up out of the engine at an angle with no room for error and I think could indeed splash back into the manifold...ask my #4 cylinder how it likes the repeated salt water baths from the PO and its reduced compression as a result.
edit - Here is the 'upgrade' I made and the comparison to the original C-30 design.