Last week I started my engine at the dock as I hadn’t run it for a several weeks. I noticed that the sound of the exhaust sounded different than usual. Like there wasn’t enough water flowing through it. I ran the engine under load, up to 2000 rpm, and the temp gauge read normal, which is about 82C. But still the exhaust sounded funny.
I started to investigate, firstly by cleaning out the raw water sea strainer, there was some seaweed and other bits of stuff in it but not too bad. There was a diver nearby cleaning boat bottoms, so I got him to check the thru hull to ensure it wasn’t blocked, and he said it was all clear.
Then, with the help of a friend, we took off the raw water impeller cover to inspect the pump, all looked fine, and the impeller had been replaced earlier in the spring. Then we removed and checked the thru hull-sea strainer-raw water pump hoses, all clear. (Tip: to remove the stiff heavy duty hose from thru hull to sea strainer, use a small pipe wrench on the hose to wiggle it a bit to loosen off the sea strainer brass fitting. And blue rubberized garden gloves are very helpful to pull-off/push-on hoses, as well as many other boat tasks.)
The next day I bought some Salt-Away, and gave the engine a treatment. Firstly closing the thru hull, then removing the incoming hose from the sea strainer and replacing it with a inexpensive clear temporary hose to a 5 gallon bucket with the blue Salt Away solution. Ran the engine until blue liquid came out the exhaust, then shut down and let it sit overnight. I still had plenty of Salt Away leftover in the bucket so I did a second treatment the next day. While there may have been a slight improvement, the exhaust still didn’t sound right.
My heat exchanger was replaced with a brand new one 4 years ago, so I didn’t think it was the problem. But to be sure, I took one end cap off my heat exchanger, and bingo… one side was about 90% clogged with some calcium deposits that I suspect are barnacle related. Really surprised the engine didn’t run hotter given the amount of blockage.
I cleaned the tubes with a stainless welding rod, which is somewhat similar to a coat hanger if you’ve never seen one. Then cleaned out the debris and tube end with a 3M green scrub pad. A small mirror is very helpful when doing this as its pretty tough to see inside the end cap. After this I bought some Barnacle Buster, and ran a treatment using same method as I did with the Salt Away, again leaving it overnight.
After cleaning, before Barnacle Buster:
After Barnacle Buster:
The end cap and gasket were all in good shape so I didn’t have to replace them, but I do carry a spare set onboard just in case. I also would use a Dremel tool with a nylon brush attachment (Amazon.ca) to clean the end area of the heat exchanger, but I didn’t have this Dremel attachment at the time, I do now.
After reconnecting the thru hull hose and running the engine to flush out the Barnacle Buster, the exhaust sound and water flow was back to normal. Checked the hoses and engine for leaks, especially the heat exchanger, all good.
One thing I wonder about is why are there only calcium/barnacles on one half of the heat exchanger end as shown in the photo? Anyone know?
Also, I didn’t remove the other end cap of the heat exchanger as its much harder to get at, and a lot harder to clean, I’m hoping its okay. Any thoughts?
Cheers,
Don
PS - I am writing this to further test the Discourse discussion site. It was super easy to post the cellphone photos as well. My Android phone is linked to my Windows 11 PC using Microsoft’s app “Phone Link”, so I could simply copy and past the photos into the Discourse text.