Beta 38hp Engine Has Stopped Heating Hot Water

[PaulN]

Can anyone help please? My Beta 38hp engine BV1505 model has stopped heating the domestic hot water. There are flow and return connections on the heat exchanger form a loop via the hot water cylinder, but for some reason it has stopped flowing and pipework remains cold. I slackened the top connection to the cylinder in case of an air lock, but no luck.

The engine is being cooled ok by the raw water running through the heat exchanger, so thermostat is OK. Any ideas please?

[annv]

Hi Paul remove cap from header tank and fill with coolant then release clip on the flow pipe at top of cliforior   from engine start engine then gently remove hose from joint holding it close when water starts to spurt out push hose back on and re tighten clip run engine at higher revs than replace cap on header tank after checking the level, if this is successful you had a air lock in hose you need to check tightness of ALL hose clips before your next trip and before you start the engine remove cap and check coolant level. John

[PaulN]

On 04/10/2022 at 13:32, annv said:

Hi Paul remove cap from header tank and fill with coolant then release clip on the flow pipe at top of cliforior   from engine start engine then gently remove hose from joint holding it close when water starts to spurt out push hose back on and re tighten clip run engine at higher revs than replace cap on header tank after checking the level, if this is successful you had a air lock in hose you need to check tightness of ALL hose clips before your next trip and before you start the engine remove cap and check coolant level. John

Thanks for your help John, but that is exactly what I have done and still no joy. All jubilee clips are tight and I don't loose coolant. There is a sensor switch in the header tack sending to an alarm and low level light to the dash panel at the helm. I just can't understand how the flow and return pipework loop can be blocked as it only has 50/50 water antifreeze solution in the system.

[DaveRolaves]

On my beta there are taps on the flow and return t- is one blocked or has the tap been turned off.

[MargeandParge]

Any sign of antifreeze in the hot water system ?

Regards Marge and Parge 

[Ray]

I had a similar problem with my Nanni engine. In the end I checked along all hoses using a laser point thermometer and found a cool spot at the highest point in the system where there was a join. I replaced the joint with a connector that had a bleed screw.

(If I remember correctly it was Smoggy that suggested the thermometer 👍)

[annv]

Hi Paul if you have full flow of coolant to califora is the hose cold or just warm if just warm your thermostat is the culprit it has failed in the open position, if no full flow the inside of the hose has collapsed. John

[PaulN]

18 hours ago, DaveRolaves said:

On my beta there are taps on the flow and return t- is one blocked or has the tap been turned off.

Hi Dave. No there are no taps on the flow and return to the HW tank, only a drain tap for the whole coolant system, but thanks for your help.

[PaulN]

18 hours ago, MargeandParge said:

Any sign of antifreeze in the hot water system ?

Regards Marge and Parge 

Hi M&P. No there is no trace of antifreeze in the HW system and the coolant is steady at about 25mm below the cap on the coolant header tank (as per engine manual), so I'm not losing any coolant, but thanks for your help.

[PaulN]

17 hours ago, Ray said:

I had a similar problem with my Nanni engine. In the end I checked along all hoses using a laser point thermometer and found a cool spot at the highest point in the system where there was a join. I replaced the joint with a connector that had a bleed screw.

(If I remember correctly it was Smoggy that suggested the thermometer 👍)

Hi Ray. The Nanni is a very similar engine to te Beta, both are marinised Kubota's as you no doubt know. The flow pipe near the engine is luke warm and the return is cold, so I don't think there can be a cold poin, however thanks for your help.

[PaulN]

2 hours ago, annv said:

Hi Paul if you have full flow of coolant to califora is the hose cold or just warm if just warm your thermostat is the culprit it has failed in the open position, if no full flow the inside of the hose has collapsed. John

Hi John. My engine is running at 75-77 deg C which is normal and the thermostat of course has to open to control the cooling from the raw water. With the engine running at this correct temperature, then I assume the antifreeze coolant running through the heat exchanger should be supplying to the HW cylinder as well, thanks for you help though.

[PaulN]

What a great forum. All these lovely people trying to help. 

Can anyone advise me what actually pushes the heated coolant through the pipework to the HW cylinder. This I am not sure of.

[Smoggy]

The coolant often goes through the calorifier before the stat opens like a bypass circuit, I'm pretty certain the take offs on my volvos are like this.

[MargeandParge]

59 minutes ago, PaulN said:

What a great forum. All these lovely people trying to help. 

Can anyone advise me what actually pushes the heated coolant through the pipework to the HW cylinder. This I am not sure of.

Works like a heater matrix in your car should heat the calorifier before the thermostat opens. So it's the engines water pump that circulates the hot water to the coil inside the calorific.

Kindest Regards 

Marge and Parge 

[Andrewcook]

Just for interest why can you just take off the Radiator Cap with the engine running at a fair speed and get the Air lockout that way?

[MargeandParge]

Hi Paul 

Check your feed and return hoses right through as they are normally half inch heater hose and can collapse or kink when bent. 

No jokes about kink and bent in the same sentence please . 

Kindest Regards 

Marge and Parge 

[BroadAmbition]

Just for interest why can you just take off the Radiator Cap with the engine running at a fair speed and get the Air lockout that way?

You can when the engine is cold started, blipping the throttle and hand squeezing a flexi coolant pipe helps (If there is one) but you need to have the cap in hand ready for when the thermostat opens and the coolant starts to expand

Griff

[Smoggy]

Try taking the cap off when up to temperature and you are likely to get a face full of scalding coolant, I know of a guy that did just that and had skin falling off his face.

Cold there's usually air in the header anyway, in a perfect system air will always get back to the header but perfect systems are a big ask on a boat.

[Vaughan]

53 minutes ago, Smoggy said:

Try taking the cap off when up to temperature and you are likely to get a face full of scalding coolant, I know of a guy that did just that and had skin falling off his face.

Please beware!   The Nanni and Beta have a pressurised cooling system which is not the same as the good old Perkins or BMC.

This is one of the main reasons why hire boat companies these days do not even "lift the floorboards" when giving a trial run to customers.  They simply say "if it overheats, stop the boat at once and call the boatyard".

On the other hand, and as ANNV describes, you can use the pressure in the system to blow an airlock out of the calorifier pipes, by simply easing the right Jubilee clip and bleeding the air out, while the engine is running at normal temperature - and pressure.

Please NEVER take the pressure cap off the heat exchanger or expansion chamber of a Nanni or Beta engine when it has just been running and is up to its normal temperature.

[Smoggy]

The guy I know had a 1.5 bmc when he got badly burnt, it was overheating at the time but shows they CAN be pressurised especially if the overheating is down to a head gasket or cracked head.

[annv]

Hi Paul the water flow is pumped around the engine by a impeller ie water pump the flow to the califora comes from the rear of the had through califora and back to the water pump housing if not getting hot it is because the pipes are blocked or the thermostat is in the open fail position this wont stop engine getting hot but will take longer as the water flows through the heat exchanger constantly remove cap remove hose from califora does the water pour out if yes remove return does water flow from califora .if it flows your problem is the thermostat. John 

[Smoggy]

2 hours ago, annv said:

pumped around the engine by a impeller ie water pump

Be aware John means the engine water pump not the raw water pump, easily to get confused if you're not mechanically minded, they both have impellors just different types (the raw water is the one you change regularly).

[PaulN]

On 06/10/2022 at 14:38, Smoggy said:

The coolant often goes through the calorifier before the stat opens like a bypass circuit, I'm pretty certain the take offs on my volvos are like this.

Thanks Smoggy. Yes, I believe the Beta is the same

[PaulN]

On 06/10/2022 at 14:56, MargeandParge said:

Works like a heater matrix in your car should heat the calorifier before the thermostat opens. So it's the engines water pump that circulates the hot water to the coil inside the calorific.

Kindest Regards 

Marge and Parge 

Thanks Marge and Parge, I agree but the engine temp is always steady at about 75 deg C so I guess the thermostat is ok

[PaulN]

On 06/10/2022 at 14:56, Andrewcook said:

Just for interest why can you just take off the Radiator Cap with the engine running at a fair speed and get the Air lockout that way?

Thanks, but tried that and no joy