water temperature warning light

[2Greyhounds]

I'm looking for some help with an issue. The water temperature warning light comes on after about 3 hours cruising - any ideas as to why and what can I look at?

[ditchcrawler]

Obvious question, is the engine overheating

[Richard T]

Inadequately sized skin tank assuming that the engine is cooled by one. 

[Dr Bob]

The problem with instrument panels and warning lights is that you never know if they are telling porkies.....but often they are. Buy yourself an infra red thermometer .......often referred to on here as an infrequent red thermometer thingy due to the actions of the auto spell checker.... and a bottle of gin. 

You can then monitor the temp on the top of the block and see if it has risen when the light comes on. If it does, then you can drink the gin to calm your nerves whilst seeking a solution here. If it doesn't then you can calm your nerves anyway.

Seriously, I got one for  £30 ish and it identified a significant issue with my 2 alternators being at different temperatures. 

[Jennifer McM]

31 minutes ago, Richard T said:

Inadequately sized skin tank assuming that the engine is cooled by one. 

.... and could the skin tank want bleeding?

[Wanderer Vagabond]

1 hour ago, 2Greyhounds said:

I'm looking for some help with an issue. The water temperature warning light comes on after about 3 hours cruising - any ideas as to why and what can I look at?

If there are no obvious signs of overheating I'd be looking at the warning light sensor in the engine (having replaced mine for much the same reason). The handy thing about the temperature warning is that there will be other symptoms (steam, boiling water) but I also had to change my oil warning light sensor for the same reason and because if the oil pressure fails the symptoms are the engine grinds to a halt

[blackrose]

10 hours ago, Jennifer McM said:

.... and could the skin tank want bleeding?

Yes, that's an easy first step if you haven't already done it?

[2Greyhounds]

Thank you for your replies. Everything seems to be working as it should, the water flow through the system is fine (thermostat works, skin tank has been bled) its just that after a run of 3 hours the pesky light comes on. We can get it to go by running off hot water from the calorifier and i will take on board your suggestion as to what I can look at.

 

Thanks.

[Wanderer Vagabond]

1 hour ago, 2Greyhounds said:

Thank you for your replies. Everything seems to be working as it should, the water flow through the system is fine (thermostat works, skin tank has been bled) its just that after a run of 3 hours the pesky light comes on. We can get it to go by running off hot water from the calorifier and i will take on board your suggestion as to what I can look at.

 

Thanks.

This suggests even more to me a dodgy sensor for the warning light. If there was a real issue with the engine overheating it would happen a lot quicker that 3 hours. Having said that the sensor is vastly overpriced for what it is, effectively it is a switch but on my Lister LPW4 comes in at a mouth-watering £90.

[Alan de Enfield]

8 minutes ago, Wanderer Vagabond said:

This suggests even more to me a dodgy sensor for the warning light. If there was a real issue with the engine overheating it would happen a lot quicker that 3 hours. Having said that the sensor is vastly overpriced for what it is, effectively it is a switch but on my Lister LPW4 comes in at a mouth-watering £90.

That's why I bought a complete spare engine (LPWS4) and re-con gearbox - the cost of components + time taken to find a supplier and get them delivered made it worth while.

Fortunately I never needed to use any components, having now sold the boat it is just sat in my shed.

[rusty69]

Just now, Alan de Enfield said:

That's why I bought a complete spare engine (LPWS4) and re-con gearbox - the cost of components + time taken to find a supplier and get them delivered made it worth while.

Fortunately I never needed to use any components, having now sold the boat it is just sat in my shed.

I have an eye on that shed.................

[Wanderer Vagabond]

11 minutes ago, Alan de Enfield said:

That's why I bought a complete spare engine (LPWS4) and re-con gearbox - the cost of components + time taken to find a supplier and get them delivered made it worth while.

Fortunately I never needed to use any components, having now sold the boat it is just sat in my shed.

The poster RLWP on the boards has been pretty good when I've needed parts (water pump) and I also have a Lister main dealer near my postal address. Even the main dealer was a bit shocked at the cost of what was effectively a switch.

[Alan de Enfield]

3 minutes ago, Wanderer Vagabond said:

The poster RLWP on the boards has been pretty good when I've needed parts (water pump) and I also have a Lister main dealer near my postal address. Even the main dealer was a bit shocked at the cost of what was effectively a switch.

I just like to think I can phone up Son and say bring an alternator / starter motor / Injectors / Fuel pump / gear box etc and know it can be there same day. No repairs simply 'plug & play'.

It may takes days / weeks to travel somewhere by boat but there is not much of the country that cannot be reached by car in under 8 hours.

[Wanderer Vagabond]

1 minute ago, Alan de Enfield said:

I just like to think I can phone up Son and say bring an alternator / starter motor / Injectors / Fuel pump / gear box etc and know it can be there same day. No repairs simply 'plug & play'.

It may takes days / weeks to travel somewhere by boat but there is not much of the country that cannot be reached by car in under 8 hours.

I do note your comment,"... Fortunately I never needed to use any components...." so it sounds like the theory was good, fell down a bit on the practice

[ditchcrawler]

1 minute ago, Wanderer Vagabond said:

I do note your comment,"... Fortunately I never needed to use any components...." so it sounds like the theory was good, fell down a bit on the practice

Or very good insurance.

[Wanderer Vagabond]

1 minute ago, ditchcrawler said:

Or very good insurance.

Depends on how much the engine cost to buy really. If it is sitting rusting in a garage it would be a bit of a nuisance if it was arranged to get an alternator/fuel pump etc brought up to the boat, fitted it and then found it was duff.

[Alan de Enfield]

35 minutes ago, Wanderer Vagabond said:

I do note your comment,"... Fortunately I never needed to use any components...." so it sounds like the theory was good, fell down a bit on the practice

"Better to have and not to need than need and not to have"

 

No - its not 'rusting' its quietly sat in a nice dry container and everything was working when it went in.

[rusty69]

Just now, Alan de Enfield said:

 

No - its not 'rusting' its quietly sat in a nice dry container and everything was working when it went in.

If it Rusty's I'll pick it up in the morning 

 

[WotEver]

It could still be an undersized skin tank as suggested by Richard in post #3. Is this boat new to you, or is this a boat you’ve had a while and the problem is new?

[ditchcrawler]

Is the OP 100% sure the switch is not operating at the correct temperature New ones are not cheap  https://www.asap-supplies.com/high-temperature-warning-switch-90-degrees

[Tony Brooks]

Although I would normally suggest changing the switch first (if it is a switch and not combined switch and gauge sender) the cost is such that the OP needs to do some proper diagnosis as suggested by Dr Bob. That is to actually measure the engine temperature. Failing that I would be seeing if a sensor from a car has the correct thread and a similar closing temperature.

 

The comment about running hot water off to stop it certainly suggest that it may be a skin tank problem and woolly assertions like "Everything seems to be working as it should, the water flow through the system is fine (thermostat works, skin tank has been bled)" really do not help the diagnosis. How dies the OP KNOW the water flow through the system is fine, and that does not rule out an undersized skin tank. How does the OP KNOW the thermostat works as it should - has he tested it?

 

Logical diagnosis with definitive steps and results are what is called for, not assertions. What is the engine temperature  measured by an external source when this happens?

[2Greyhounds]

Thanks again for more replies. To answer some of the points raised ....

We have had the boat a few years and this is a recent issue.

After bleeding the skin tank, I ran the engine for about an hour and felt the pipework for temperature rise. I also checked the skin tank which was warm at the top and cold at the bottom (unfortunately I wasn't able to do this after the light came on).

 

Would a faulty thermostat take 3 hours to show? Also, I will check the engine temp once I can get a thermometer.

 

As always your help and advice is appreciated.

 

Edited May 21, 2018 by 2Greyhounds

[Flyboy]

43 minutes ago, 2Greyhounds said:

Thanks again for more replies. To answer some of the points raised ....

We have had the boat a few years and this is a recent issue.

After bleeding the skin tank, I ran the engine for about an hour and felt the pipework for temperature rise. I also checked the skin tank which was warm at the top and cold at the bottom (unfortunately I wasn't able to do this after the light came on).

 

Would a faulty thermostat take 3 hours to show? Also, I will check the engine temp once I can get a thermometer.

 

As always your help and advice is appreciated.

 

I would suggest you remove the thermostat and suspend it in a saucepan of water and heat it to boiling point. If you have thermometer you can see at what temperature it starts to open and when it's fully open. It may be only partially opening and allowing some water to pass to the skin tank. This may be the cause your overheating after 3 hours.

[Tony Brooks]

1 hour ago, 2Greyhounds said:

Thanks again for more replies. To answer some of the points raised ....

We have had the boat a few years and this is a recent issue.

After bleeding the skin tank, I ran the engine for about an hour and felt the pipework for temperature rise. I also checked the skin tank which was warm at the top and cold at the bottom (unfortunately I wasn't able to do this after the light came on).

 

Would a faulty thermostat take 3 hours to show? Also, I will check the engine temp once I can get a thermometer.

 

As always your help and advice is appreciated.

 

 

That seems much more definite and as long as the bottom hose is still cold when the buzzer sounds it rules out the skin tank but please re-bleed it just to be sure.

 

That's best because you do not want to sell out £44 for a new switch it it turns out to be a short on the wiring. Once you know the engine temperature is within limits pull the warning wire off the sender while it playing up. If the noise stops it confirms the sender is at fault. If it doesn't then the wiring is suspect OR its a charging or oil pressure fault.

 

 

30 minutes ago, Flyboy said:

I would suggest you remove the thermostat and suspend it in a saucepan of water and heat it to boiling point. If you have thermometer you can see at what temperature it starts to open and when it's fully open. It may be only partially opening and allowing some water to pass to the skin tank. This may be the cause your overheating after 3 hours.

Especially if there has been a recent overheat for some other reason. Modern thermostats can eject wax when over heated and then they open at a higher temperature than they should and may not open far enough.

 

 

 

Edited May 21, 2018 by Tony Brooks

[jonathanA]

Do we know what type the engine is ? 

 

I would be be tempted to add a cheap water temperature gauge sender and gauge - can be had off eBay for less than a tenner. 

 

Or look for a none genuine or car part -  worth a punt as plenty on eBay for a few quid.

Edited May 21, 2018 by jonathanA
Remove silly suggestion