Exhaust Not Emitting Enough Water with Exhaust

[swahealy2]

Have a Catalina 37 with a Diesel and the exhaust is loader than normal and the water coming out is very sporadic. The intake valve to the cooling water is open just behind the keel. The engine temperature is climbing to over 190 and the exhaust has little to now water coming out. I am thinking I have a clogged inlet. Any suggestions how to unclog without pulling the boat?

[Lowcountry]

1) check your sea strainer for seaweed or other debris
2) check your waterpump impeller and belt
3) check your heat exchanger for clogs

[swagman]

Originally Posted by swahealy2

Have a Catalina 37 with a Diesel and the exhaust is loader than normal and the water coming out is very sporadic. The intake valve to the cooling water is open just behind the keel. The engine temperature is climbing to over 190 and the exhaust has little to now water coming out. I am thinking I have a clogged inlet. Any suggestions how to unclog without pulling the boat?

You can stay in the water and simply close that inlet valve then remove the hose in the bilge to check for a blockage inside the pipe.
If you find no blockage then fill a big bucket (or your bilge) with water and hold the inlet hose in it and firte up the engine again. If it does not suck up water immediately then you know it's your impeller.
If it does suck up water then you know the blockage is outside behind the keel so afraid the option is then to dive or haul her out.
Leave time between each of these to minimse risk of overheating the engine.
Cheers
JOHN

[Lowcountry]

4) check your exhaust elbow for blockage.

[swahealy2]

John, I follow you when you talk about removing the hose after closing the inlet valve. I can put the hose in a bucket of water to see if it sucks up water. I don't know if I have an impeller or not. The Catalina talks about a design of a wet muffler system that I believe uses the back pressure of the exhaust to draw the cooling water through the engine radiator? Have you experienced this type of exhaust before? Thanks for you quick reply.

[Misiu]

Originally Posted by swahealy2

Have a Catalina 37 with a Diesel and the exhaust is loader than normal and the water coming out is very sporadic. The intake valve to the cooling water is open just behind the keel. The engine temperature is climbing to over 190 and the exhaust has little to now water coming out. I am thinking I have a clogged inlet. Any suggestions how to unclog without pulling the boat?

How old is the boat? In addition to what Lowcountry suggested you may also look at the exhaust riser. It is also a common problem area.

I would start from the intake and follow the entire seawater route and look for problems. I don't think you need to pull the boat out of the water. If you are worrying about intake on the bottom (from outside) you may ask diver to take a look, but I would start from the most common causes as mentioned by Lowcountry and above.

[swahealy2]

Is the exhaust elbow as simple as it looks? I can take it off and check it for blockage?

[swahealy2]

Thanks guys I will start with the hull valve and work my way back up and look for blockages. The Cat is 11 years old but I had it out three weeks ago and the engine and exhaust where fine.

[Juniper]

To check the inlet, with engine stopped, close the valve, open the strainer, slowly open the valve, water should pour out, if so, not plugged, if not, lightly try to force a fluid back out from the strainer out the inlet, ie water or air, do not hook it up with fittings to the dock hose or an air compressor, if you can't just press it on top you will need more work, I've just blown into end of the hose to clear mine before after it sucked up some mud.

[DotDun]

Originally Posted by swahealy2

John, I follow you when you talk about removing the hose after closing the inlet valve. I can put the hose in a bucket of water to see if it sucks up water. I don't know if I have an impeller or not. The Catalina talks about a design of a wet muffler system that I believe uses the back pressure of the exhaust to draw the cooling water through the engine radiator? Have you experienced this type of exhaust before? Thanks for you quick reply.

I doubt it works this way. The wet muffler fills with water and the exhaust pressure pushes it out of the boat. But the raw water is drawn into the boat via a pump with an impeller in it. I doubt there would be enough vacuum on the exhaust to draw in the raw water.

Follow the hoses, you'll find the pump. Take the cover off the pump and you'll find the impeller.

[swahealy2]

Thanks Juniper, all you guys have given me a number of things to check. I'll use the AC since I think I am going to be down in the hole a long time.

[zeehag]

you have an impeller if you have a raw water pump. i also have a wet exhaust--and a raw water pump. and a strainer and alladat stuff-----first check your strainer. then water filter pre engine. then raw water pump. then elbow. then .......
i bet is easy fi8x... goood luck. you shouldnt have to haul just for this.

[DotDun]

Originally Posted by Juniper

To check the inlet, with engine stopped, close the valve, open the strainer, slowly open the valve, water should pour out, if so, not plugged

Not necessarily, if the strainer is above the water line, opening it will simply ruin the prime on the pump and you'll see no water coming in.

Assuming the pump is below the waterline, close the intake valve, take the inlet hose off the pump, then open the valve and see if water comes out.

[SkiprJohn]

If your impeller is good you'll suck the water out of a 5 gal. bucket really quickly so be ready to shut the engine down fast. No need to keep the engine running because you've isolated the problem. I've not heard of an engine that doesn't have an impeller of some kind that pumps seawater through a heat exchanger (radiator). Wet exhaust means that the saltwater is piped into the exhaust system downstream of the exhaust manifold to cool the exhaust before it goes through plastic mufflers and rubber hoses.

Follow the hose from your seawater intake valve and the first thing that it ends at should be a pump that's driven by a belt from your engine. The impeller will be inside that pump.

Let us know what you find and maybe we can help more.

kind regards,

[Lancerbye]

My bet would be a plugged strainer or a plastic bag over the intake started the problem, however by now you might have cooked your impeller which will also have to be checked before testing again.