Beta 25 Overheat

[BigStu]

Hi all

Just picked up a 'new' boat Cobra 850 with a Beta 25- bit of an adventure getting her to the mooring....

I managed to get nearly to my mooring… then a slowed the engine to idle to do some thing on the bow (was on my own) and it cut. I tried to restart and it started but the overheating light and alarm where going, then a bit of smoke in the cabin, so cut it straight away. Drifting into the dockyard- I got picked up by the Police patrol who took me to my mooring (great service- but they were not happy!).

Before it happened- the engine seemed fine for a good hour, running at 2000 revs- all seemed fine. I had sped up a touch before all this happened. On inspection, oil is fairly new and clear by the looks of it (no milkyness), no fresh water in cooling system however- but I suspect it had shed it somewhere along the line??. Filled system with fresh- started the engine and raw water pumping fine, barely luke warm at exhaust, everything looks normal and then idled happily for about 10 mins and then revved it to 2000 for 5 mins- again seemed fine. I checked there was fresh water in system before I left.

Next day- all was fine. On the mooring I ran it for a good half hour at idle and 20 mins at 2000-3000 revs- no alarm. I wanted to get into the heat exchanger but the end cover is stuck solid- which makes me think it may not have been looked at for some time. Measured the flow from the exhaust and all over the recommended amounts.

It is a Beta 25 engine, 10 years old, piles of receipts in a folder for the boat since new (so looked after)- what do you think has gone on here? I'm hoping this is not going to be a common occurrence! Granted she needs a good service...but what else I wonder?

 

[DickieT]

Would not think it is anything too serious. I would suspect the heat exchanger. The Beta cooling system is pretty straight forward but I always think the system works a bit on the "edge" and it does not take much to put it into an overheat condition. Check the impeller, simple enough, but suspect there maybe old bits of previous impeller in the tube stack. End plates and the stack itself can be difficult enough to remove if not done regularly. I do mine every season and it is an easy 10 minute job, BUT have read can be very difficult if left too long. I suspect the loss of FW from the system was down to the system boiling over and dumping all the coolent out of the top cap. The "smoke" you saw - steam ? An expansion tank (mine from a breakers yard) is a worthwhile addition. Good luck, have a good clean of the heat exchanger ! Richard

 

[DickieT]

Forgot to say...The Beta recommendation is for a 50/50 mix of water and antifreeze, this to raise the boiling point of the water. I have a temp gauge, and mine, if pushed hard, for any length of time, will hover around the 90c mark, so not much "headroom" in the overheating department! Also, of course, make sure inlet salt water strainer clear.

 

[Poecheng]

I have the BD722 20hp and, prior to purchase, read a bit about Beta overheating. I have never myself experienced it over about 150hrs usage.
As DickieT has said, the stack is critical and on our first service ours was definitely in need of a good clean - there is a Beta video on youtube from memory about this.
I also read about the effect of inlet pipes and seacocks - quite often these are marginal in size and benefit from an increase in size.
From recollection, those who cleaned the stack properly and who increased the inlet pipe/seacock size seemed to have no further problems.

FWIW, I wouldn't start swapping the inlet pipe etc unless I found that the engine was overheating with a known clean stack.

 

[PetiteFleur]

I had overheating on my Beta25 about 4 yrs ago - then 6 yrs old. I cleaned out the heat exchanger, the exhaust end had bits of grunge & impellor rubber in it. I used a piece of steel rod to clean the tubes( a stripped welding rod actually), reassembled and it was fine. I do change the anode every year as thzt is as long as it lasts.
My problem is it is now running cool after fitting a new calorifier, not sorted this one yet even after fitting new thermostat and temp. sender.

 

[Kwik Decision]

Forgot to say...The Beta recommendation is for a 50/50 mix of water and antifreeze, this to raise the boiling point of the water. I have a temp gauge, and mine, if pushed hard, for any length of time, will hover around the 90c mark, so not much "headroom" in the overheating department! Also, of course, make sure inlet salt water strainer clear.

The key reason that Beta recommend a maximum of 50% antifreeze is used is that the heat capacity of ethylene glycol, the main component of antifreeze, is a lot lower than water, and is therefore less efficient at removing heat.* If there is neat antifreeze in your system, this may be the reason for over heating. A bit of a long shot though, my money would be on a) the coolent level in the heat exchanger being a bit low, a very easy one to check and fix, or b) the heat exchanger being fouled, as described above.

* While the antifreeze will also increase the boiling point of the the coolant a little, it should be noted that the cooling system is designed to run at pressure (14 psig, if memory serves), and therefore even with just water in, the cooling system won't boil until around 120 deg C, hence there is a reasonable margin above normal op temp of around 90 deg C.

 

[BigStu]

Hi all

Thanks for the advice. I managed to get the tubestack out- pig of a job as the front cover was stuck fast. Not too blocked up, but a fair bit of gunk in there. I'll replace this week and see what happens. I have managed to purchase all the items for an expansion tank from eBay for about £20, so I'll go down that route if things don't sort themselves out.

When doing a service- I'll do all the filters, oil change, anode, belt, impeller etc whilst I'm there- but is there anything else I need to be looking at for a service on these particularly?

 

[30boat]

Hi all

Thanks for the advice. I managed to get the tubestack out- pig of a job as the front cover was stuck fast. Not too blocked up, but a fair bit of gunk in there. I'll replace this week and see what happens. I have managed to purchase all the items for an expansion tank from eBay for about £20, so I'll go down that route if things don't sort themselves out.

When doing a service- I'll do all the filters, oil change, anode, belt, impeller etc whilst I'm there- but is there anything else I need to be looking at for a service on these particularly?

This is my installation.I got the expansion tank for less that 10€ and the rest was straightforward.It completely cured the tendency of the alarm to go off.

 

[DickieT]

Good, sounds like you are on the way to getting it sorted. My reason for the expansion tank was that I was loosing a little water ever time the engine became warm and this was obviously not being replaced. As I was saying in my previous post every little bit helps when it comes to cooling and I not want to loose any water.
While you are doing this service it would do no harm to remove the exhaust (injection) elbow. My Beta is now 16 years old, very pleased with it, but am now on my third elbow. First one I replaced with a home made stainless one, lasted about 7 seasons. It was stainless (316). When it started to go I fitted the (current?) Beta aluminium one. Seems a good job, not expensive 5 years ago and still showing no signs of corrosion. However I remove it every year for a look. Again removing these things regularly saves hassle with stubborn fastenings. BTW I always lightly smear the O rings and end caps with silicon grease, although any water proof grease would do. You probably doing so anyway but replace the end cap O rings and I also have replaced the Dowty type seals under the brass end cap bolts. Good luck with it. Richard

 

[Poecheng]

When doing a service- I'll do all the filters, oil change, anode, belt, impeller etc whilst I'm there- but is there anything else I need to be looking at for a service on these particularly?

A) Just to emphasise the anode; mine goes through them fairly rapidly and they need a new one every season. Not particularly a cost issue but just be ready to change 'em every six months (our season afloat)
B) Our stop solenoid started being difficult; it turned out that it simply wasn't grounding properly which a bit of wd40 sorted and then reseated properly at the end of the season. Not a bad thing to work out in advance where the manual stop is and how it works.

These are all normal things but passing on my experience.

 

[Kwik Decision]

Re: Expansion Tank

I'm interested in the fact that people are fitting expansion tanks. I had a new Beta 25 fitted by TS Marine about 18 mths ago, and it started loosing a small amount of coolant into the bilge. I was seriously considering an expansion tank, but when talking to Scott at TS Marine, he was adamant that it wasn't required on a normal installation. He gave me a new heat exchanger cap, and this cured the problem, so I guess the old one was faulty and leaking a little......

Note that the heat exchanger cap is the same as a radiator cap on a car. It is designed to allow the cooling system to pressurise to around 14 psig, before leaking, to prevent the pressure from getting too high. On my engine there is a length of plastic tube coming from just under the cap which direct any leaks to the bilge, and I now have this routed to a plastic bottle, so I can easily see if coolant is being lost.

 

[30boat]

Re: Expansion Tank

I'm interested in the fact that people are fitting expansion tanks. I had a new Beta 25 fitted by TS Marine about 18 mths ago, and it started loosing a small amount of coolant into the bilge. I was seriously considering an expansion tank, but when talking to Scott at TS Marine, he was adamant that it wasn't required on a normal installation. He gave me a new heat exchanger cap, and this cured the problem, so I guess the old one was faulty and leaking a little......

Note that the heat exchanger cap is the same as a radiator cap on a car. It is designed to allow the cooling system to pressurise to around 14 psig, before leaking, to prevent the pressure from getting too high. On my engine there is a length of plastic tube coming from just under the cap which direct any leaks to the bilge, and I now have this routed to a plastic bottle, so I can easily see if coolant is being lost.

Well yes but the fact is that Beta's cooling system is a bit marginal and many engines lose coolant and their overheating alarms go off.An expansion tank cures that and allows the lost coolant to return to the engine after it's been forced out.

 

[LittleSister]

Re: Expansion Tank

When I first had our Beta 14 engine (came with boat but nearly new) I kept topping up the water level. Then I noticed that it was always down to the same level (about an inch below the mouth of the filler), never higher or lower. I tried not topping it up. It stayed at the same level. I stopped topping it up, and it has remained at the same level for the last 6 years.

Overheating hasn't been a problem. During that time the engine has, for instance, driven the boat into a head wind (at decent revs/load), for over 22 continuous hours on one trip; near flat out for 6 hours on another; and completely flat out for about half an hour on another; and has clocked up an additional 600 or so hours.

If a header tank solves someone's particular problems, then fine. But that doesn't mean there's anything generally wrong with Beta cooling.

 

[Hydrozoan]

Re: Expansion Tank

When I first had our Beta 14 engine (came with boat but nearly new) I kept topping up the water level. Then I noticed that it was always down to the same level (about an inch below the mouth of the filler), never higher or lower. I tried not topping it up. It stayed at the same level. I stopped topping it up, and it has remained at the same level for the last 6 years. ...

If a header tank solves someone's particular problems, then fine. But that doesn't mean there's anything generally wrong with Beta cooling.

Yes, I've noticed the same (20 year old Beta 622) and, whilst checking carefully, don't top up too much and encounter little or no overspill. At first, I was a bit concerned as the level seemed a bit low in relation to the heat exchanger element, but I have never had overheating problems.

 

[alahol2]

When doing a service- I'll do all the filters, oil change, anode, belt, impeller etc whilst I'm there- but is there anything else I need to be looking at for a service on these particularly?

It is well worth draining, flushing through and re-filling the 'fresh water' side of the cooling system. This sometimes means poking about with a bit of stiff wire at the drain plug to get the water flowing.