Beta 20 overheating...

[Seagreen]

So yes, the venerable BD722 is not liking to be pushed more than 1800 rpm, without the overheating alarm going off.

I have made sure the inlet seacock isnt blocked and enough water "seems" to be going through. However, I notice the impellor is a 10 blade jabsco rather than the usual 6 blade Beta, which I think may account for the problem. I've not had an impeller shred on me for many years so I don't really think a blockage is the problem. Also, I think the extra fireproofing about the engine box may be an issue, but surely the water cooling should take that into account, and a fan system isn't really needed?

My money's on the impeller. Any other opinions welcome.

 

[cagey]

Have you checked the heat exchanger, needs rodding through occasionally
Bol
Keith

 

[earlybird]

Has the 10 blade impeller been OK in the past? Not difficult to swap.
Certainly the H/E is a possible culprit.
The temperature switch might be iffy.
If you invest ~£10 in an ebay non-contact infra-red thermometer, the H/E shows ~80-85 deg. C. At least, it does on my B25.

 

[TangaraToo]

I had the same issue with the Beta 12. Plenty of water seemed to be coming out with exhaust but heat exchanger was around 50% blocked.
If it hasn't been stripped out in the last couple of years then it would be my guess.

 

[Habebty]

I have a BD722 which can suffer bouts of overheating. I ended up changing the skin fitting and seacock for a larger diameter hole!
Seemed to help but I have just fitted a new raw water pump which came with a 6 blade impellor, which got me thinking too. I started a thread on here asking the question which impellor would pump the most water, a 6 or 8 blade impellor?
Before anyone answers that question, I suggest they read that thread first!
http://www.ybw.com/forums/showthread.php?474852-Impellor-Question-hmmmm

I think it boils down to (no pun intended!)
Keep the HE clean
Antifreeze at the correct mix
Header tank topped up
Position, size of water intake ( is laminar flow over the hull preventing efficient intake?)
Air leak in raw water strainer?

 

[Seagreen]

The engine has been fine for years, and its about 10 years old, well serviced and with about 250 hours. I shall fit a correct impeller, and give the whole cooling system a good poke through. The Impeller was sold to me as a 'good fit' by a yard, (no names as I still do business with them). I may get a non-contact thermometer, but I shall try the obvious things first. The engine has been fine so far, so I don't think the seawater inlet is a problem.

 

[Hydrozoan]

I have an older Beta BD622, otherwise very similar. I have not encountered overheating despite having had different (6 or 8 bladed IIRC) impellors at different times. I have not had a blocked H/E either, though I did once find a few bits of impellor blade in it from before my time. I agree with the above comments and, if the strainer is clear and the coolant level/antifreeze strength OK, would examine the H/E and - if that's clear - consider the temperature switch (not that mine has given me any trouble either).

Good luck with it.

 

[chrishscorp]

I have an older Beta BD622, otherwise very similar. I have not encountered overheating despite having had different (6 or 8 bladed IIRC) impellors at different times. I have not had a blocked H/E either, though I did once find a few bits of impellor blade in it from before my time. I agree with the above comments and, if the strainer is clear and the coolant level/antifreeze strength OK, would examine the H/E and - if that's clear - consider the temperature switch (not that mine has given me any trouble either).

Good luck with it.

Virtually as above with ours, she ran slightly warm when over 2000 revs which was bits of impellor from before my time in the tubes of the H/E. Kiddies pipe cleaners are ideal tool. From what i was told the guys that make the impellor changed the number of blades on the impellor so it depends whether it is a new one or old one as to how many it has.

They are pretty reliable units to be fair, keep us posted

 

[Keith 66]

I have a Beta 16 in our Sabre, the heat exchanger tube stack is very compact & will block with salt very quickly. I clean it out twice a season otherwise we get problems.

 

[Seagreen]

New Impeller has arrived from ASAP supplies. Impressed it comes with a sachet of lubricant. Pipe cleaners mentioned, but as I've not cleaned out a heat exchanger before, what tools or gadgets (like wire and scrubbies etc) would be useful? Any warnings about what not to poke?

 

[cagey]

Your biggest problem is going to be removing the stack, I now clean it in situ. Before you start get 2 new o rings and engine anode, it is possible to reuse old rings but not worth the risk they always leak. Take off both end caps, one is hidden behind alternator but that folds out of the way and the other at engine anode end then if your not removing stack prod through from alternator end and collect crap on a rag. I use a slightly undersize twist drill and spin it with my fingers. There are a lot of holes to clear out but by shining torch through one end you will see if it is badly blocked and how much you have cleared. I hope it is blocked because that will be your problem.
Reassembly is reverse,except clean all thecrap from mating surfaces, I hold new rings in place with smear of vaseline as well as giving new rings a thin coat as well, to help them bed in. Fit new anode now so you can see if it needs trimming. The anode end cap has locating pegs to line it up with core.
Keith

 

[earlybird]

I have a Beta 16 in our Sabre, the heat exchanger tube stack is very compact & will block with salt very quickly. I clean it out twice a season otherwise we get problems.

That seems a bit extreme. I've owned 2 Beta engines since 2004, first a B662 and, since 2012, a B25.
I've never cleaned the stack in either of them. Each was/ is fitted with a temperature gauge, so deterioration of H/E performance would be seen.
I must thank clean Scottish seas for this!

 

[PuffTheMagicDragon]

When I had a fresh-water cooled engine for rodding I used to use long bamboo skewers as are commonly used for kebabs and barbecues.
Best is if you can remove the tube nest. Placed in a plastic tub that contains a very dilute hydrochloric acid mixture any trace of furring will be removed and rinsing in fresh clean water will have the tube-nest 'as new'. This was the recommendation that was in the Lombardini manual; at first I was reluctant to try it but it really worked. The tubes were made of some inox material whose name I forgot; if yours are made of a different material try a weaker solution or a milder acid. Even vinegar will do at a pinch but this will be safer and will take longer (overnight).

 

[Hydrozoan]

That seems a bit extreme. ...

Agreed, I have never encountered blockage like that.

I clean out the H/E tube stack with a long wooden skewer as Puff suggests, though I’m sure a pipe cleaner would do just as well (look through the stack against a light as suggested). But unless there is serious amount of coating on the stack I would do only that – IMO acid cleaning, if not necessary to remove heavy deposits, merely creates more unpassivated metal surface to consume your H/E zinc.

Getting the H/E stack right out if you decide to go that way (I do) may be a bit tricky but careful perseverance is the answer. Be aware that, if it’s like mine, there are detents (?) in the end caps which must be aligned with matching sections on the H/E stack for a proper re-fit onto the O-rings (new and vaselined, I agree).

A search of the forum should reveal more discussion of Beta H/E servicing, should you feel you need it. It’s not that difficult if you proceed carefully - good luck!

 

[Habebty]

The first time I replaced my stack I managed to shear an end cap bolt (they are bronze) -order some spares but a stainless one will do for a very short time.

 

[gandy]

Regarding impellers, Beta used Jabsco pumps originally (10 blade), then changed to Johnston (six bladed impeller). So the correct impeller will depend on the age of the engine, assuming original sea water pump. The spares listing suggests the change was summer 2006.

 

[Pye_End]

That seems a bit extreme. I've owned 2 Beta engines since 2004, first a B662 and, since 2012, a B25.

I do mine every 2 seasons. When it is reasonably good condition it comes apart easier.

Different areas no doubt require different timescales, but well worth taking apart when 2 or 3 seasons old to see what is going on.

If it is not easy to dismantle after all this while, I wonder if it is possible to chemically treat it rather than risk damage to the stack?

 

[Hydrozoan]

I do mine every 2 seasons. When it is reasonably good condition it comes apart easier.

Different areas no doubt require different timescales, but well worth taking apart when 2 or 3 seasons old to see what is going on.

If it is not easy to dismantle after all this while, I wonder if it is possible to chemically treat it rather than risk damage to the stack?

Yes, I used to think 2 years was what Beta recommended but I think they now (and possibly always did) recommend annually. I may be mistaken in that, but it’s a good point that a long-neglected stack may be difficult to remove, and my comment about avoiding acid cleaning of the stack itself was not intended for that situation.

My concerns about in-situ chemical cleaning (other than just of the insides of the tubes of course) would be the trickiness, and potential attack on the (in my case aluminium) housing. If the stack is stuck in the ends of the housing by deposits, chemical treatment of those areas of contact might I guess help to free it. (On mine there’s also another 'ring' of contact between the stack and the housing inside, and to reach that you’d have to fill the housing; but just treating the ends might give helpful ‘wiggle-room’.) I guess you’d have to make a plasticine ‘cup’ around the ends to hold the de-scaling agent (and block off with a pad of plasticine the entrance to the tubes – on the ‘uphill’ end at least!).

Unless you can think of a better way?

 

[jim.howes]

Yes, I used to think 2 years was what Beta recommended but I think they now (and possibly always did) recommend annually. I may be mistaken in that, but it’s a good point that a long-neglected stack may be difficult to remove, and my comment about avoiding acid cleaning of the stack itself was not intended for that situation.

My concerns about in-situ chemical cleaning (other than just of the insides of the tubes of course) would be the trickiness, and potential attack on the (in my case aluminium) housing. If the stack is stuck in the ends of the housing by deposits, chemical treatment of those areas of contact might I guess help to free it. (On mine there’s also another 'ring' of contact between the stack and the housing inside, and to reach that you’d have to fill the housing; but just treating the ends might give helpful ‘wiggle-room’.) I guess you’d have to make a plasticine ‘cup’ around the ends to hold the de-scaling agent (and block off with a pad of plasticine the entrance to the tubes – on the ‘uphill’ end at least!).

Unless you can think of a better way?

 

[gandy]

The stack is seized in our heat exchanger. Advice from Beta was to clean it in place, which is easy enough with both end caps removed. Theoretically the other surface shouldn't get dirty should it? I'd like to think of a way of checking for leaks between seawater and coolant sides though.