cmedsailor
Well-Known Member
Is it a good idea to have an exaust temperature alarm just in case your impeller fails and don't realise it immediately? Any particular alarms / shops to buy from?
Thanks
Thanks
Exaust temperature alarm
- Thread starter cmedsailor
- Start date
charles_reed
Well-Known Member
Re: Exhaust temperature alarm
IMHO redundant - the overheat alarm tells you immediately on a raw water cooled engine and in plenty of time on a indirect cooled engine.
If you change the impeller every 1000 hours it's most unlikely to fail.
Just something else to go wrong!!
IMHO redundant - the overheat alarm tells you immediately on a raw water cooled engine and in plenty of time on a indirect cooled engine.
If you change the impeller every 1000 hours it's most unlikely to fail.
Just something else to go wrong!!
rob2
Well-Known Member
Re: Exhaust temperature alarm
Yes, the temperature alarm will save your engine before you're into warped cylinder heads, etc. However, an exhasut temperature alarm will also save you the cost of a new exhaust hose. This stuff doesn't like flames and will delaminate/disintegrate quickly if burnt. It is also pretty expensive!
Yes, the temperature alarm will save your engine before you're into warped cylinder heads, etc. However, an exhasut temperature alarm will also save you the cost of a new exhaust hose. This stuff doesn't like flames and will delaminate/disintegrate quickly if burnt. It is also pretty expensive!
cmedsailor
Well-Known Member
Re: Exhaust temperature alarm
Ah, there is probably a good point here. The engine panel has a coolant temperature alarm. This of course measures the temperature of the water which I guess will get hot after the exchaust. Could we wait for this? In other words could we suffer a damage from the time the impeller goes wrond until coolant water temperature rises and the alarm sounds?
Thanks
Ah, there is probably a good point here. The engine panel has a coolant temperature alarm. This of course measures the temperature of the water which I guess will get hot after the exchaust. Could we wait for this? In other words could we suffer a damage from the time the impeller goes wrond until coolant water temperature rises and the alarm sounds?
Thanks
JerryHawkins
Well-Known Member
IMHO, if you wait until the engine water temp alarm goes off (certainly with indirect and most likely even with raw cooling), the exhaust hose will have melted and/or caught fire. If you have an exhaust temp alarm, it will go off moments after flow of injected water stops so you can stop engine almost before the water temp has even started to rise.
cmedsailor
Well-Known Member
..... and my second question....any particular alarm products to look for?
Thanks
Thanks
JerryHawkins
Well-Known Member
I fitted the Vetus one.
vyv_cox
Well-Known Member
<<< IMHO, if you wait until the engine water temp alarm goes off (certainly with indirect and most likely even with raw cooling), the exhaust hose will have melted and/or caught fire. >>>
My experience tells me differently. My engine has gone through a period of not priming itself after sailing in fairly choppy seas, probably due to wear in the cover plate for the pump. On many occasions the high water temperature alarm has sounded before we realised, without ever damaging the exhaust hose and traps. Nowadays we are more aware of the situation and can usually hear that there is no water passing through. Since changing the pump cover the problem has almost, but not quite, gone away.
My experience tells me differently. My engine has gone through a period of not priming itself after sailing in fairly choppy seas, probably due to wear in the cover plate for the pump. On many occasions the high water temperature alarm has sounded before we realised, without ever damaging the exhaust hose and traps. Nowadays we are more aware of the situation and can usually hear that there is no water passing through. Since changing the pump cover the problem has almost, but not quite, gone away.
DavidMcMullan
Well-Known Member
My boat is fitted with an HMI Exhaust Alert, made by a company called Halyard. www.halyard.eu.com
cliffordpope
Well-Known Member
[ QUOTE ]
If you have an exhaust temp alarm, it will go off moments after flow of injected water stops
[/ QUOTE ]
Not in my experience.
When laying up my 1GM10 last month I wanted to flush out all sea water, fill it with antifreeze to prevent corrosion, and also blast any standing water out of the exhaust pipe. I couldn't do this afloat, because I needed the engine right up to the last moment for manoeuvring onto the trailer.
So I cautiously ran the engine ashore with the water intake in a bucket of antifreeze, and disconnected the water outlet from the elbow and fed it back into the bucket. I was surprised to find that the exhaust pipe was barely warm even after a few minutes running.
If you have an exhaust temp alarm, it will go off moments after flow of injected water stops
[/ QUOTE ]
Not in my experience.
When laying up my 1GM10 last month I wanted to flush out all sea water, fill it with antifreeze to prevent corrosion, and also blast any standing water out of the exhaust pipe. I couldn't do this afloat, because I needed the engine right up to the last moment for manoeuvring onto the trailer.
So I cautiously ran the engine ashore with the water intake in a bucket of antifreeze, and disconnected the water outlet from the elbow and fed it back into the bucket. I was surprised to find that the exhaust pipe was barely warm even after a few minutes running.
Nauti Fox
Well-Known Member
ebbtide
N/A
Please register my vote for the Halyard duo which monitors both exhaust temperature and cooling water flow; it's so quick I don't always check the seacock before starting - I get deafened if I've forgotten!
"If you change the impeller every 1000 hours it's most unlikely to fail."
Really? My engine has a full service every 400 hours and the old impeller has been found damaged every time.
"If you change the impeller every 1000 hours it's most unlikely to fail."
Really? My engine has a full service every 400 hours and the old impeller has been found damaged every time.
chuzzlewit
Well-Known Member
An article in PBO a few years ago showed how a flow switch fitted in the rubber pipe from the water pump gives instant warning if the water flow stops. I fitted it for under £10 and it works a treat.
charles_reed
Well-Known Member
My experience
with two engines in this boat is that it's always worked in plenty of time.
To prevent impeller damage you need a good water-trap and to clean the filter regularly.
Damage, usually occurs as the result of slovenly maintenance.
I have had impellers go without warning, usually due to wear on the shoe or faceplate. The solution is to have the pump re-machined.
with two engines in this boat is that it's always worked in plenty of time.
To prevent impeller damage you need a good water-trap and to clean the filter regularly.
Damage, usually occurs as the result of slovenly maintenance.
I have had impellers go without warning, usually due to wear on the shoe or faceplate. The solution is to have the pump re-machined.
charles_reed
Well-Known Member
Possibly
you also have plenty of warning due to the change in the exhaust note.
Possibly if the engine is running flat out and your reaction is delayed you could damage the hose. However I don't see that an exhaust alarm will save more than a few seconds, and I suspect the hose will still be damaged.
It's an inessential addition which, following Sod's Law will lead to other problems.
you also have plenty of warning due to the change in the exhaust note.
Possibly if the engine is running flat out and your reaction is delayed you could damage the hose. However I don't see that an exhaust alarm will save more than a few seconds, and I suspect the hose will still be damaged.
It's an inessential addition which, following Sod's Law will lead to other problems.
Tarka1
Well-Known Member
I bought an adjustable temperature switch and sounder from Maplins. You have to assemble it yourself but the advantage is you can adjust it so that it triggers with a small increase in temperature giving you plently of time to react to any potential problem.
Best of all it cost less than a tenner!
Best of all it cost less than a tenner!
nedmin
Well-Known Member
Re: Possibly
I first fitted a water temp alarm about 25yrs ago due to picking up weed on inland waterways. Radio spares do a thermal switch with a normally open contact were about £3. Get the 100 deg centigrade one. put a blob of Araldite on it and temporary fasten it to the exhaust outlet as near to engine as possible.The reason for this is if you pick a "hotspot" on the exhaust you can move it and then Araldite it better later.Rather than picking up a 12volt supply I used a 9volt pp3 battery put the thermal switch, 9volt battery and a piezzo alarm in series and you have an alarm for a few quid.If you put a switch across the thermal switch you can then test the system.The prob. with flow switches are you could fill the bilges with water due to a leak and the alarm would not go off.The above alarm wont save your impeller but will save your engine.
I first fitted a water temp alarm about 25yrs ago due to picking up weed on inland waterways. Radio spares do a thermal switch with a normally open contact were about £3. Get the 100 deg centigrade one. put a blob of Araldite on it and temporary fasten it to the exhaust outlet as near to engine as possible.The reason for this is if you pick a "hotspot" on the exhaust you can move it and then Araldite it better later.Rather than picking up a 12volt supply I used a 9volt pp3 battery put the thermal switch, 9volt battery and a piezzo alarm in series and you have an alarm for a few quid.If you put a switch across the thermal switch you can then test the system.The prob. with flow switches are you could fill the bilges with water due to a leak and the alarm would not go off.The above alarm wont save your impeller but will save your engine.
pete
Well-Known Member
I fitted one of these a few years ago its well made and easily fitted. I have also fitted a water flow switch and connected it to the same alarm.
I did have problems before I fitted this with the pump not always priming after the boat had dried out, I thought I had got away with it but on removing the first bit of exhaust hose after the engine which looked perfect outside, the inside had de laminated almost blocking it completely and the water lock spout had just started to melt.
pete
I did have problems before I fitted this with the pump not always priming after the boat had dried out, I thought I had got away with it but on removing the first bit of exhaust hose after the engine which looked perfect outside, the inside had de laminated almost blocking it completely and the water lock spout had just started to melt.
pete
Bodach na mara
Well-Known Member
I fitted a similar version to the one described by nedmin on my last boat, however I used a 75 degree switch as on test it did not close until it reached 90.
I fitted it after melting a Vetus waterlock, which was some distance from the engine. The intake had become blocked (by jellyfish!) and before the engine temperature guage was showing anything abnormal, the damage was done. And the rubber exhaust between the engine and waterloak was not too clever either. The first indication was the noise and smoke pouring from the after cabin. An engine overheat alarm is not adequate against failure of the primary cooling system.
I fitted it after melting a Vetus waterlock, which was some distance from the engine. The intake had become blocked (by jellyfish!) and before the engine temperature guage was showing anything abnormal, the damage was done. And the rubber exhaust between the engine and waterloak was not too clever either. The first indication was the noise and smoke pouring from the after cabin. An engine overheat alarm is not adequate against failure of the primary cooling system.
