Beat 20 water temp buzzer sounding

[kevsbox]

Hi All
On sunday we took our new yacht out for a spin around Portsmouth Harbour to get to know her. She is a Westerly Centaur with a Beta 20 engine.
For 2 hours we pottered around the harbour at about 4kn and then decided to return to the pontoon. During this time no problems and there was plenty of water pumping out and no smoke.
Then the water temp buzzer kicked in and because we were newarly back I slowed slightly but continued. Still water coming through but now also a little smoke.
We made it back ok and tomorrow I will start to look around the engine but has anyone got any ideas why this would happen after a couple of hours of running with no problem?

Thanks in advance

Kev

 

[LittleSister]

I suspect the 'smoke' may have been steam.

Most likely, I imagine, cooling water intake is partially blocked by weed, plastic bag or whatever. If so the obstruction may well fall off once the engine is stopped and hence suction ceases.

Next most likely, I think, the impeller has failed - e.g. blade broken off or rubber blades moulding slipping on the central metal driven bush.

On your return, start the engine, run it under load, and see if it is still overheating. If so take cover plate off raw water pump and inspect (ideally replace) the impeller. If impeller looks good, but engine still overheating, poke through the open inlet seacock with a stick or whatever to dislodge any obstruction.

Could also be failed thermostat, but unlikely I think.

Hopefully others more knowledgeable than me will be along shortly with more/better ideas.

 

[graham]

I have the same engine in a Centaur. I would check everything that Little Sister suggests.

If a blade is missing from the impellor the bits may be in the end of the heat exchanger blocking some of the tubes .not a big job to get the end caps off but ideally you need new o rings to reassemble it.



You can check if you have enough cooling water coming out the exhaust by setting the RPM at 1000 ,

catch the water exiting the exhaust into a bucket for 10 seconds multiply the amount in your bucket by 6 to give you litres/ minute. The minimum is 6.5 litres/minute.(mine does over 10 litres)

Good luck I hope the fix is simple.

PS if you are on facebook theres a Beta Marine ownrs group which I have found usefull .

 

[ash2020]

Maybe a blockage in the heat exchanger.

 

[VicS]

Hi All
On sunday we took our new yacht out for a spin around Portsmouth Harbour to get to know her. She is a Westerly Centaur with a Beta 20 engine.
For 2 hours we pottered around the harbour at about 4kn and then decided to return to the pontoon. During this time no problems and there was plenty of water pumping out and no smoke.
Then the water temp buzzer kicked in and because we were newarly back I slowed slightly but continued. Have you checked the actual flow but now also a little smoke.
We made it back ok and tomorrow I will start to look around the engine but has anyone got any ideas why this would happen after a couple of hours of running with no problem?

Thanks in advance

Kev

Have you checked the actual flow as described in the Operators Maintenance Manual:

The most common cause of overheating is insufficient seawater flow due to a blocked intake (weed or a plastic bag!). If this happens then clear the blockage. If the problem is not cured then check the system for sea water flow which should be 12 litres / minute minimum at 1,500 rpm as follows: (a) With the boat tied up and out of gear run the engine up to 1500 rpm. Hold a plastic bucket over the exhaust outlet for 10 seconds and measure the amount of water collected*. Multiply this value by 6 to give the flow in litres / minute. Repeat twice and take an average. If the flow rate is noticeably less than the 12 litre per minute minimum at 1,500 rpm, then: (b) Check impeller in sea water pump - if worn replace. (c) If impeller has a vane missing then this will be lodged either in the pipe to the heat exchanger or in the end of the exchanger. This must be removed. (d) Check flow again as in (a). *Note: This operation must only be done in safe conditions, in port and with two assistants. Working from a rubber dinghy is best. The person holding the bucket should take precautions against breathing in the exhaust gasses.​

​

Have you checked the coolant level and drive belt tension.

Consider the possibility that the thermostat is faulty

Consider also that the temperature sensor could be faulty ( beg, borrow or steal an IR temperature gun or a contact thermometer to check )

Dont have a calorifier that is allowing too greater flow to bypass the HE ??

 

[kevsbox]

Thanks for the feedback folks, plenty of things to try here

 

[TwoFish]

Maybe a blockage in the heat exchanger.

And per the service manual (actually for the Beta 28, check if yours is similar):

EVERY YEAR OR 250 HOURS IF SOONER.
Remove heat exchanger tube stack, by undoing the bolt each end of the tube stack. Remove end cover, pull out tube stack and clean. Replace rubber ‘O’ rings and re-assemble. Top up with antifreeze. Immediately engine is started check for leaks.

Thread here.

 

[VicS]

And per the service manual (actually for the Beta 28, check if yours is similar):

EVERY YEAR OR 250 HOURS IF SOONER.
Remove heat exchanger tube stack, by undoing the bolt each end of the tube stack. Remove end cover, pull out tube stack and clean. Replace rubber ‘O’ rings and re-assemble. Top up with antifreeze. Immediately engine is started check for leaks.

Thread here.

The maintenance manual for Beta 10 to Beta 25 engines is here:- https://betamarineengines.com/application/files/3616/1051/2372/1590-1025-HEKC-SOM-0314.pdf

.

 

[kevsbox]

The maintenance manual for Beta 10 to Beta 25 engines is here:- https://betamarineengines.com/application/files/3616/1051/2372/1590-1025-HEKC-SOM-0314.pdf

.

Nice, thank you

 

[kevsbox]

Found the problem, blocked seawater intake filter.