Overheating Beta 43

[frahkn]

My wife went back to the boat yesterday and changed the oil.

 

She ran the engine for 15 mins first and thought the oil was hotter than usual but made nothing of it.

 

Then she switched the engine on again, planning to run it for an hour or so. After about 10 mins the overheating alarm (sound and light) went on and the temp gauge showed 100+.

 

The boat has not been used since January but the engine was run for an hour in June with no overheating.

 

I (remotely) thought air lock, thermostat or water pump. Anything else? What would you do in these circumstances given that I cannot got to the boat at the moment?

 

Thanks.

[TheBiscuits]

Check the coolant level is correct too.

[nicknorman]

Check the small alternator drive belt that also drives the water pump isn’t very slack or bust. Check level of water in the header tank (built into the top of the engine). Presumably there isn’t some kind of shutoff valve for the skin tank circuit?

 

Feel temperature of pipes in skin tank circuit - obviously the feed should be hot all the way from the engine to the skin tank. If not, the water isn’t circulating.

 

If no joy, undo the 2 bolts that hold down the thermostat housing and remove thermostat, replace housing/bolts. Try running the engine again without the thermostat.

[cuthound]

Failing all of the above, get your wife to do oil changes on other people's boats for remuneration.

 

That way you will.be able to pay for any necessary repairs! ???

[Tracy D'arth]

1 minute ago, nicknorman said:

Check the small alternator drive belt that also drives the water pump isn’t very slack or bust. Check level of water in the header tank (built into the top of the engine). Presumably there isn’t some kind of shutoff valve for the skin tank circuit?

 

Feel temperature of pipes in skin tank circuit - obviously the feed should be hot all the way from the engine to the skin tank. If not, the water isn’t circulating.

 

If no joy, undo the 2 bolts that hold down the thermostat housing and remove thermostat, replace housing/bolts. Try running the engine again without the thermostat.

Unlikely to be the stat, seen too many removed for no good reason. Modern wax stats fail open usually. Air lock most likely, I have seen header tanks that are marginal size to cope with the expansion which cease to circulate if they lose another half pint. Soon as the exhaust gets hot they steam up and lose more water.

TD'

[nicknorman]

12 minutes ago, Tracy D'arth said:

Unlikely to be the stat, seen too many removed for no good reason. Modern wax stats fail open usually. Air lock most likely, I have seen header tanks that are marginal size to cope with the expansion which cease to circulate if they lose another half pint. Soon as the exhaust gets hot they steam up and lose more water.

TD'

Yes I agree which is why I put the stat at the end of my list, but on the other hand it’s an easy thing to check / eliminate.

 

Beta 43s have an integral header tank so all installations should have the same volume, it’s fairly large.

 

Of course the other thing we haven’t thought about is whether the engine is actually getting hot, or whether it just thinks it is.

 

Confirmation bias. The oil seemed hotter than expected but that is a bit vague. And that is then linked to the overheat alarm to mentally confirm its activation. Is there any evidence that the engine is in fact overheating, other than the alarm? Yes I know the gauge shows hot but is there just the one sensor for gauge and alarm? (Off to check the schematic...)

 

Edit... looks like there is just one sensor to feed the gauge and the warning light / alarm.

Edited July 12, 2020 by nicknorman

[Tony Brooks]

I would suggest that such engines need an external expansion tank when tank cooled. Too many examples of air getting into the skin tank without one so i would suggest top up and bleed tank before anything else (apart from visual checks) if there is no external expansion tank

[nicknorman]

1 minute ago, Tony Brooks said:

I would suggest that such engines need an external expansion tank when tank cooled. Too many examples of air getting into the skin tank without one so i would suggest top up and bleed tank before anything else (apart from visual checks) if there is no external expansion tank

Beta would disagree with you. This engine is designed for keel/skin tank cooling and no additional header / expansion tank is deemed necessary, according to the installation instructions. We certainly don’t have one on ours and when I changed the coolant a couple of years ago, bleeding it was not an issue.

[Tracy D'arth]

18 minutes ago, nicknorman said:

Beta would disagree with you. This engine is designed for keel/skin tank cooling and no additional header / expansion tank is deemed necessary, according to the installation instructions. We certainly don’t have one on ours and when I changed the coolant a couple of years ago, bleeding it was not an issue.

But it depends on the volume of the water in the system.

If the expansion is more than the volume left in the expansion tank after circulation is possible, there will be water loss on heating, so next time it is fired up there is insufficient water for circulation to start.  It boils.

TD'

[Jen-in-Wellies]

29 minutes ago, nicknorman said:

Beta would disagree with you. This engine is designed for keel/skin tank cooling and no additional header / expansion tank is deemed necessary, according to the installation instructions. We certainly don’t have one on ours and when I changed the coolant a couple of years ago, bleeding it was not an issue.

Another vote for Beta's engineering. My 43 also doesn't have an additional expansion tank. Copes fine with chugging up and down the Trent, including the tidal bit, which is notorious for showing up marginal cooling systems.

 

42 minutes ago, nicknorman said:

Confirmation bias. The oil seemed hotter than expected but that is a bit vague. And that is then linked to the overheat alarm to mentally confirm its activation. Is there any evidence that the engine is in fact overheating, other than the alarm? Yes I know the gauge shows hot but is there just the one sensor for gauge and alarm? (Off to check the schematic...)

The deluxe control panel, the one with both the water temperature gauge and the high temp alarm works off just one sender. The wire colour from the engine is blue with a green stripe. An output from the gauge goes to the warning lamp, so a faulty sender could cause both to be misleading. A short from the wire, or sender to ground would lead to very high temperatures reported. An open circuit to too low.

 

Jen

[Tracy D'arth]

Remember the blasted multi plugs on the engine loom.

TD'

[nicknorman]

26 minutes ago, Tracy D'arth said:

But it depends on the volume of the water in the system.

If the expansion is more than the volume left in the expansion tank after circulation is possible, there will be water loss on heating, so next time it is fired up there is insufficient water for circulation to start.  It boils.

TD'

Yes, however one would presume that this boat has been in use for a while and hasn’t suddenly had an additional header tank surgically removed. If so then a fundamental issue with the design of the system (insufficient header tank volume for the total coolant volume) is a red herring.

[Jen-in-Wellies]

6 minutes ago, Tracy D'arth said:

Remember the blasted multi plugs on the engine loom.

TD'

Usually the awful multi plug connections are a good thing to check, but this is unlikely to lead to high temperatures being reported on the panel. That requires a low resistance path to ground, not an open circuit. Negative temperature coefficient of resistance sender, earthed to the engine block, with a single wire going to the panel.

Jen

[Tracy D'arth]

9 minutes ago, Jen-in-Wellies said:

Usually the awful multi plug connections are a good thing to check, but this is unlikely to lead to high temperatures being reported on the panel. That requires a low resistance path to ground, not an open circuit. Negative temperature coefficient of resistance sender, earthed to the engine block, with a single wire going to the panel.

Jen

All true unless its in the water and oil in the bilge and has been stood on. Then anything can occur.

[Tony Brooks]

1 hour ago, nicknorman said:

Beta would disagree with you. This engine is designed for keel/skin tank cooling and no additional header / expansion tank is deemed necessary, according to the installation instructions. We certainly don’t have one on ours and when I changed the coolant a couple of years ago, bleeding it was not an issue.

Unfortunately Beta have no effective control on the skin tank design. OK, so they recommend a certain  single surface area but that so often gets ignored and the thickness could be anything from about 1/2" (good) and up to 6" (bad).

 

Just because your boat does not need an expansion tank to keep it reliable does not mean every bat with a Beta (or any other modern engine) will have. Bleeding should not be an issue but if the coolant expansion expelled sufficient water to allow air into engine will result in air building up in the skin tank, even if you top up regularly. So I say again top up and bleed the skin tank if no expansion tank is fitted and also if one is. It shoudl be easy and removes two potential causes.

[ditchcrawler]

2 hours ago, Jen-in-Wellies said:

Another vote for Beta's engineering. My 43 also doesn't have an additional expansion tank. Copes fine with chugging up and down the Trent, including the tidal bit, which is notorious for showing up marginal cooling systems.

 

 

The boat we had with a Beta use to lose its coolant because it had a big fat skin tank for some unknown reason. The header tank would be empty when cold so impossible to check the level

[Tracy D'arth]

42 minutes ago, ditchcrawler said:

The boat we had with a Beta use to lose its coolant because it had a big fat skin tank for some unknown reason. The header tank would be empty when cold so impossible to check the level

Similar with one of mine, the level in the expansion header, exhaust manifold, is critical to a pint or two. Skin tank is too fat at fore end for some reason, can't do much about it as the engine members are part of it.

I have considered cutting a port in it and putting in several sealed up empty glass bottles to reduce the volume.

TD'

[Dr Bob]

3 hours ago, nicknorman said:

Yes I agree which is why I put the stat at the end of my list, but on the other hand it’s an easy thing to check / eliminate.

 

Beta 43s have an integral header tank so all installations should have the same volume, it’s fairly large.

 

Of course the other thing we haven’t thought about is whether the engine is actually getting hot, or whether it just thinks it is.

 

Confirmation bias. The oil seemed hotter than expected but that is a bit vague. And that is then linked to the overheat alarm to mentally confirm its activation. Is there any evidence that the engine is in fact overheating, other than the alarm? Yes I know the gauge shows hot but is there just the one sensor for gauge and alarm? (Off to check the schematic...)

 

Edit... looks like there is just one sensor to feed the gauge and the warning light / alarm.

Yep. An infrequent red thermometer is an essential bit of boater's kit. Easy to check the temp of all the bits of the engine.

[nicknorman]

1 hour ago, ditchcrawler said:

The boat we had with a Beta use to lose its coolant because it had a big fat skin tank for some unknown reason. The header tank would be empty when cold so impossible to check the level

 

16 minutes ago, Tracy D'arth said:

Similar with one of mine, the level in the expansion header, exhaust manifold, is critical to a pint or two. Skin tank is too fat at fore end for some reason, can't do much about it as the engine members are part of it.

I have considered cutting a port in it and putting in several sealed up empty glass bottles to reduce the volume.

TD'

Yes but none of that is relevant to a long-standing installation that doesn’t normally suffer from that problem but is currently having a problem.

[dmr]

4 hours ago, Tracy D'arth said:

Unlikely to be the stat, seen too many removed for no good reason. Modern wax stats fail open usually. Air lock most likely, I have seen header tanks that are marginal size to cope with the expansion which cease to circulate if they lose another half pint. Soon as the exhaust gets hot they steam up and lose more water.

TD'

Just to add something to the "forum knowledge base", I have only had one thermostat fail and it was getting progressively more unwilling to open, so over a couple of weeks the engine was running hotter and hotter. I fit a new one every few years and one of those was a bit lazy with its opening but settled down after a few days.

 

................Dave

 

 

 

[ditchcrawler]

6 minutes ago, dmr said:

Just to add something to the "forum knowledge base", I have only had one thermostat fail and it was getting progressively more unwilling to open, so over a couple of weeks the engine was running hotter and hotter. I fit a new one every few years and one of those was a bit lazy with its opening but settled down after a few days.

 

................Dave

 

 

 

I think mine may be going the other way or then again maybe the temperature indicator is.

 

[Midnight]

5 hours ago, frahkn said:

My wife went back to the boat yesterday and changed the oil.

 

She ran the engine for 15 mins first and thought the oil was hotter than usual but made nothing of it.

 

Then she switched the engine on again, planning to run it for an hour or so. After about 10 mins the overheating alarm (sound and light) went on and the temp gauge showed 100+.

 

The boat has not been used since January but the engine was run for an hour in June with no overheating.

 

I (remotely) thought air lock, thermostat or water pump. Anything else? What would you do in these circumstances given that I cannot got to the boat at the moment?

 

Thanks.

For the first 4 years our Beta 43 used to run hot and occasionally the warning buzzer would sound usually when there was an air lock in the skin tank which was frequent. I used to vent the system very regularly until a fellow boater mentioned the Beta 43 required about 6 square feet of skin tank. I had a second skin tank fitted and have not had an issue and never needed to vent it since. If the fan belt is the required tension, you're certain it's not an air lock and there's no doubt that the temperature is indeed very hot, I would suggest looking at the thermostat as it's so easy to check (In my day wax thermostats failed shut). I also seem to remember someone saying Betas required 50/50 antifreeze mix to run at the correct temperature.

Edited July 12, 2020 by Midnight

[TheBiscuits]

5 hours ago, Midnight said:

a fellow boater mentioned the Beta 43 required about 6 square feet of skin tank.

 

Beta recommend a square foot of skin tank for every 4 horsepower, so a 43 should have 11 square feet.

 

Many inland boats rarely get used at half power, so they only find out they have insufficient cooling when running hard against fast flowing water on a big river or a tidal section.  When pootling along a canal at 3 mph they seem fine because the small skin tank can cope.

[Tony Brooks]

9 hours ago, nicknorman said:

 

Yes but none of that is relevant to a long-standing installation that doesn’t normally suffer from that problem but is currently having a problem.

Except there is a better than evens chance the boat has just sat there since last autumn so a slight weep would have lowered the level that might have allowed air into the system.

9 hours ago, dmr said:

Just to add something to the "forum knowledge base", I have only had one thermostat fail and it was getting progressively more unwilling to open, so over a couple of weeks the engine was running hotter and hotter. I fit a new one every few years and one of those was a bit lazy with its opening but settled down after a few days.

 

................Dave

If a waxstat is overheated it can leak the wax so that increases the opening temperature. From that we can conclude that id one leaks through age or production fault that is exactly what will happen.

[Detling]

Is it possible some oil escaped onto the hot engine bits whilst it was being changed. This would cause a hot oil smell but the engine would be fine.