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Hi I have a leak of engine coolant into engine bay.Only seems to happen when I increase revs over a hour or so or more.If I travel at at1000 revs no problem. Anyway did service today and when I pulled up oil mat things there was more liquid in there than I thought, when mopping it out with a roll of paper towels I noticed the blue tint, so must be coolant.My question is if it's only happening on sustained higher revs, it's hard to find where it is coming from, any tips on detection.I was thinking of wrapping the hoses up in kitchen roll and seeing what's wet after an hour or so, but there's probably better ideas.its a semi trad so it's rarely bone dry in engine hole, any tips? It's an Isuzu 42 in a aquiline nb.Thanks in anticipation.

 

 

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Obvious starting point is all the jubilee clips , particularly as it happens when the engine is run hard it could point towards the connections to the skin tank/s and or the calorifier pipes as until its up to 85 degrees the thermostat will still be closed, like you say a bit of kithchen roll is a good indicator.... also check the water pump as most have a tell tale hole that weeps when the bearing starts to wear out.

 

Rick

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I put a small tray, such as those you get with supermarket meat in, under potential leak points, both to act as a 'tell tale' and stop the fluid spreading. I keep one permanently under my (bone dry) Volvo stern seal, so a quick glance is a reliable check. This also works well under coolant pipework joints, but kitchen paper at key points in a dry bilge is my favourite for tracing a leak. Just be careful of entanglement, blockage or fire hazard once the engine is running and alternator fans start blowing.

Any existing fluid sloshing around in the bilge makes identifying leaks and dangers such as a leaky weed hatch much more difficult, so I'm fortunate that my trad stern keeps the environment out so I can keep the bilge clean and dry. If it didn't, I'd certainly be spending some effort on trying to keep rain water out. 

Edited by Sea Dog
Autocorrect re-correction!
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Ah I see, I will cover them as well, thanks

 

1 minute ago, philjw said:

Maybe way too obvious but is any overflow due to expansion of coolant caught in the usual lemonade bottle or is this, if there is any, dropping into the bilge?

I don't understand, I'm not engine savvy?

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When water is heated it expands and if the coolant level is too high can mean that the volume is bigger than the system can hold. There is usually a small pipe, often below the pressure cap, through which excess coolant is expelled.  Many of us catch this by attaching a tube leading to a bottle. Without this the coolant drops into the bilge.

It is more likely to happen if too much coolant is added when topping up.

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This is an image from another thread. If you look under the filler cap (the silver one that says "Tighten") you will see the stub of the overflow pipe. This one looks to have a leak from the pressure cap and or the overflow.

IMG_20170601_110718.jpg

 

 

Edited by philjw
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5 hours ago, philjw said:

Maybe way too obvious but is any overflow due to expansion of coolant caught in the usual lemonade bottle or is this, if there is any, dropping into the bilge?

I had same engine in one of my old boats and that was the problem..expansion water does go straight to bilge..when checking water level in header it should just touch your outstretched finger ..any deeper and it will expand out

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Hi again,well I put paper round some pipes I suspected,made sure all the engine bay was nice and dry and clean.then put paper towels on the engine bay floor as shown in pictures.

. I then took off for about three quarters of an hour ,and happened on a boat yard so I pulled over and spoke with the very helpful man from (parvis bridge)I explained the situation to him and was going to buy some pipes in anticipation.

He had a look for me, and said as water was in engine bay and not obviously coming from any of the joints on top of engine it was probably coming from the  expansion pipe from filler cap. Reasons possibly warmer weather warmer canal water and revving more than usual, overfilling water tank. Etc and to keep on a eye on it. He put my mind at rest somewhat and agrees with what the forum suggested, fantastic. When I stopped there was no signs of any leakage , but hadn't been going that long.

So I thought that's fine, I will check again when I moor up as long as the forecast rain doesn't effect my plan, but I never had too far to go. 

I stopped at next lock to do some shopping and have lunch, when I started off again another boat joined me in the lock , a nice middle aged couple with an older man in front bay holding front line in lock, I am single handing the boat for a few days, all went well until noticed the older man had tied off the front rope going down in lock, the man doing the gate on that side of his boat rushed down to help untie it, I dropped the paddles on both gates and ran down to open a paddle to refill,, but my boat wasn't tied obviously so it now moved back to the gushing gate, so back of boat got a good torrent till I pulled it back forward,not a problem, but water got onto back deck, it also started to rain heavily like a storm of biblical proportions for that five minutes of drama, and when I eventually got moored up twenty minutes later, and looked in engine bay, there's half an inch of water in bilge and engine bay by the looks of it, can't really see it in last pic, ha so none the wiser from that experiment and wasted an hour this morning ha, so now dealing with the problem by drinking cold beer and listening to loud music to block out noise of the current deluge!,

Anyway thank you for your help, going on tidal Thames next, so was a bit worried,problem not cured but I am not too worried now ,as I now think I know what it is, I will have to follow that expansion pipe, and see where it is emptying out, I fill the tank to about a finger nail down from filler cap, is that over filling it ?

thanks again for your knowledge!.

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Engine bay soaked, back of boat where got deluge and pic of current weather on wey

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I agree that you are over filling. On an old post Tony Brooks has advised that you find out what is right for your engine by first filling right to the top, running the engine up to full operating temperature and allowing the engine to cool. Now when you remove the filler cap the level that the coolant is at is where you should fill to in future.

I see that the overflow from your engine does have a black pipe attached. If the end of that is going straight into the bilge, put it into a container.

Glad you have set your mind at rest.

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57 minutes ago, Timx said:

Thank you, rediculous I did not know this, embarrassing, but lesson learnt,hopefully

Why would you know before you were told? Everyone is learning every day :)

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Thanks , I have never even driven a car , and automobiles have always bored me, trying to keep a boat going is probably not a sensible but enjoyable life style. I continue to learn and this forum is very helpful. I can change the oil, and filters , top up the battery, probably over filling it, but when that goes wrong, only bow thruster wet cell battery, I will learn again.thanks again

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20 hours ago, linnit said:

I fill the tank to about a finger nail down from filler cap, is that over filling it ?

 

Yes....it should be a finger depth from cap

Not really correct for all boats.

The amount of coolant expansion will depend on the volume of coolant and that varies from boat to boat. Some skin tanks are vert thin and some very fat. Some have a large surface area and some much less.

It is very important to ensure all the air is bled from the cooling system unless its self bleeding because air expands more that coolant mixture.

Once you are sure there is no air in the system fill just once to the base of the filler neck. Then go for a good run to get the coolant up to temperature. It will almost certainly blow some liquid out. Allow it to cool down and then check the level. Whatever it is then be it an inch down, a finger nail or a whole finger that is the correct filling level. However on a few boat you may find it si so low that when your refill you trap air in the system. Then its time to have a decent sized (truck size) expansion bottle fitted.

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3 minutes ago, Tony Brooks said:

Not really correct for all boats.

The amount of coolant expansion will depend on the volume of coolant and that varies from boat to boat. Some skin tanks are vert thin and some very fat. Some have a large surface area and some much less.

It is very important to ensure all the air is bled from the cooling system unless its self bleeding because air expands more that coolant mixture.

Once you are sure there is no air in the system fill just once to the base of the filler neck. Then go for a good run to get the coolant up to temperature. It will almost certainly blow some liquid out. Allow it to cool down and then check the level. Whatever it is then be it an inch down, a finger nail or a whole finger that is the correct filling level. However on a few boat you may find it si so low that when your refill you trap air in the system. Then its time to have a decent sized (truck size) expansion bottle fitted.

Sorry..I tried:unsure:

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Absolutely and I expect that is correct for your boat. Unfortunately its all too easy to believe that boats are like cars that are now so similar design wise such things will be correct across a whole range of makes and models. Boats are best considered one offs.

Top marks for trying and giving advice that is unlikely to cause further problems.

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On 2017-7-27 at 10:51, mross said:

The jubilee clips may be too tight and/or the hose may be perishing or damaged under them.  That's why it's a good place to look for leakage.

In addition to this, for those who might be unaware and the OP who's clearly learning about his cooling system (nowt wrong wi that, as someone said earlier), here's something else to consider about Jubilee (and similar) clips on hoses. When the water in the system gets hot, the flange the hose is on will be hotter than the Jubilee clip (which has rubber insulation under it) and may expand more. If the clip is over tightened, this can compress the hose beyond its ability to recover. What then happens is that the system doesn't leak when it's hot and everything is tight, but rather weeps later as things cool down. So, when you're trying to find a leak on your running engine, or checking for leaks after fitting a hose, all can appear well. Next morning, or for new hoses a few days later, there's coolant in the bilge. Furthermore, because there's now no pressure in the system, the leak has stopped. Coloured coolant stains, tell-tale containers or kitchen paper may be your only way to find such a pesky leak and, where this is the cause, the natural reaction to tighten the jubilee clip won't help matters. Another clip, further towards the end of the hose and not so tight, might get you out of trouble. Worth bearing in mind as you're upside down in the bilge, trying to get an extra quarter turn on that clip, just for good measure!

Edited by Sea Dog
Autocorrect re-correction!
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