Thoughts on replacing cooling hoses

White Shadow

Active Member
Feb 17, 2023
117
Vancouver, BC
Boat Info
320 Sundancer 2005
AB Dinghy w/9.9 Merc
Axiom 9 MFD
Kohler Model 5E Generator
Engines
Twin Mercury 350 MPI Horizons w/Bravo III Drives
Hi Folks - Just wondering what peoples thoughts are on replacing all the cooling hoses and clamps on my 2005 320 DA.

The background behind this question stems from last fall when I had a clamp let go on one of my hoses (specifically the hose between the distribution housing and the heat exchanger). This happened after a weekend away while returning to our marina. I only found out there was a problem when the high water bilge alarm started going off and I realized there was an awful lot of water being pumped out the side of the boat. Luckily we were only about a mile out and managed to limp back in safely (although a bit shaken with that alarm going non-stop). After spending a boat buck getting everything cleaned up with salt away I started thinking maybe I should consider spending another boat buck (or two?) and just get all the hoses and clamps replaced. I mean they are all about 18 years old now.

Is this overkill? Am I over reacting?? Should I take a close look and only replace hoses that look like they need it, or just clamps that look like they should be replaced? Or maybe just add a second clamp where I can? I know typically when you start fixing this type of thing that other problems arise. Like the hose barbs starting to leak where they didn't before - that type of thing.

Any opinions on this? Anyone done something similar and replaced all their cooling hoses and clamps? Was there a lot more work involved then expected (and cost)?

I don't ever want to hear that high water alarm ever again! :)
 
Assuming you're fresh-water cooled, I'd be inclined to replace anything between the outdrives and heat exchanger. Basically, anything that could have seawater running through it.
How much work really comes down to how tight it is in the bilge. My '92 300DA has just about no room down below, what with the water heater to port and the genny to starboard. That's with an eleven foot beam. YMMV
 
I’m gonna be accused of being a tight-wad, but I wouldn’t replace any hose that looks good. That said, I ABSOLUTELY would double clamp everything with stainless clamps. Great insurance against that alarm!
 
I had one from the strainer collapse internally, so it looked fine from the outside, but under pressure the metal jacket inside would collapse and the engine would overheat. Took weeks to figure it out because the hose looked fine. So I replaced a heat exchanger, other hoses, thermostat, etc. I replaced them all. No more wasting time diagnosing in the middle of the summer.
 
I helped a friend replace all his hoses last season because they had become hard and brittle. The inside of the hoses had started to collapse and you couldn't tell from the outside. He also had a mysterious alarm that would go off when coming off plane that went away after we changed the hoses. So YES changed all the 18 year old hoses.
 
I might be a tight wad, but I’d like to think I’m relatively intelligent, after reading these posts, I’m leaning more towards changing hoses…..gonna start looking at mine.
 
Our boat is a 1989 I had all the hoses replaced in 2006 along with the oil and transmission cooler. They are still good. In 2018 the insurance survey pointed out the hose from the sea strainer to the engine raw water pump was starting to crack. The old one looked OK inside but new one was more firm.
 

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