Its the pipes - cooling water hose (YAWN)

[Elissaar]

Dear All

I wonder if you can help on what is hardly an eye catching subject. Having spent the last month with my head in the cockpit locker fixing a leak in the hot water system (split pipe) it dawns on me that the cooling water hoses for the engine should probably be renewed (uses a larger diameter but same hose type).

Current hoses (as fitted by Najad 7 years ago) are clear (well they used to be!), PVC hose with a metal coil embedded in the wall. Vetus do it this stuff for £2 a metre (would need about 10 metres) and its designed for pressure water systems. However, the fact that a hose in the water system split is making me think I better think of replacing the stuff for the engine (it might be important). What should I replace it with, the same or something more substantial? The engine is indirectly cooled with sea water (its an MD2030). What do poeple usually use that can go round bends without collapsing.

Sorry I tried to make it short and witty but have failed.

Simon

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[steve_cronin]

Surely the cooling hoses to and from the engine and heat exchanger & pump ar rubber just like the ones on your car? The only flexible ones are the sea water inlet from the Kingston cock to the sea water pump and from it to the heat exchanger and the sea water outlet from the heat exchanger to the exhaust elbow via the anti-syphon bend. These can be helically reinforced PVC as they don't take any pressure. Also transparent hose gives you a visual that sea water is flowing.

Some people change all the hoses every three or four years and make Volvo dealers very happy in the process. Others leave them for ten years or more.


Person who is careful with money's remedy:

With the rubber hoses if they're getting hard then replace them. The PVC will look tatty and discoloured when it needs replacing.

Cautious person's remedy:

Change them at regular intervals of three years to four years.

RNLI, Trinity House, River Police remedy:

Change them once a year but these craft are in almost constant use or can't afford the slightest risk of failure.

The choice is yours!

Steve Cronin



<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[Elissaar]

Steve

Thank you for your post, actually the Volvo Penta poeple suggested some green stuff whose name I forget but now I see why this see through flexible hose was used. Its definately discoloured and the visual advantage is lost so I should think about changing it when the boat/engine is serviced in April.

Simon

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[SlowlyButSurely]

I use ordinary car type heater hose from the motor factors for both the engine and domestic hot water systems. I've just changed it after 17 years use and it was all in pretty good condition, a little hard in places but no leaks.

If you think about it, this stuff is made to withstand boiling water under pressure and is well up to the job.

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[chriscallender]

ASAP supplies <A target="_blank" HREF=http://www.asap-supplies.com>http://www.asap-supplies.com</A> sell cooling hose, although its well hidden on the web site. Do a search on radiator hose, rad hose or silicone hose and you will see some hoses that can take cooling water temperatures.

I replaced all the hoses on a Bukh by removing the old fittings, and attaching them to the new fittings with stainless jubilee clips. Probably much cheaper (only a few pounds overall !) than ordering the parts from Bukh, and as I have a load of spare hose on the boat now, I am pretty confident that I could repair any hose that did blow with just a screwdriver and a knife. Because I was paranoid about leaks I put a smear of high temperature silicone sealant onto each of the joints before clamping it on, but I'm fairly sure that wouldn't be needed (and possibly isn't even a good idea).

The stuff doesn't seem to collapse on normal, gentle curves, if you need to turn one of the hoses through a big angle in a short distance then its probably best to reroute the hose and make it longer.



Chris


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[andyball]

All the clear stuff I've seen (inc. vetus) is rated to 70 C, which might be a bit low for even domestic hot water supply ,& certainly no good for hot hoses on engine.

My pal's nauticat broke down after an engineer used clear stainless reinf. hose from the waterpump on his ford engine, it sagged so much when hot that it rubbed against the pulley on the front of the motor.

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[scottie]

i think that rubber reinforced is now standard as "plastic" melts inder fire and hardens with age


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[steve_cronin]

My boat was built in 2001 and has the spirally re-inforced pvc hose for the non-pressurised runs on the raw water side. All cylinder block hoses will of course be like car hoses, reinforced rubber/butyl as they take pressurised water at high temperature.

Steve Cronin



<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[Aeolus_IV]

A marine engineer suggested to me that all essential hoses in the vicinity of the engine compartment should be fire resistant in the same way as fuel hosing should be. The argument for this is that should you have an engine fire (bad enough), you would rather not have the seawater intake pipe melt and start letting water in as well (burning and sinking at same time!).

I couldn't see any reason for not following this advice, though the fuel grade hose is more expensive.

Just my opinion of course.
Jeff.

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[steve_cronin]

I don't know how quickly a hose full of water might melt. Wouldn't the water conduct the heat away and until the water boiled away (which if the water is moving will never happen)wouldn't it remain intact?. No doubt if you hit it with a gas welding torch then it might but if an engine compartment fire gets that hot aren't you better getting it wet? I have seen remote bowden cable kingston cock actuators in the US which look like a good idea.

I've got these Lloyds and CE stickers so maybe it's been sorted?

Steve Cronin

<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[andyball]

Re. aeolus & steve

I've often thought that pipes could melt & flood a boat....others argued that no way could water filled pipe get hot enough.

Just tried it with pvc hose over the gas ring, & not much difference between empty pipe & one full of water; both got damaged in a similar amount of time. Water didn't boil, but pipe melted.

Not overly scientific of course, but fun- now have to clear water out of the cooker burner.

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[chriscallender]

Nice quick way of putting the fire out if the hose melts and the boat sinks! Cheaper than buying one of those new automatic fire extinguisher jobs for the engine compartment!!!

Chris

PS Only joking just in case anyone thought I was serious!


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