Beta 20HP coolant change and heat exchanger

chrishscorp

chrishscorp

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Purchased a yacht last year and it has a very sweet 20hp beta on board, i would like to keep it that way, as i am not sure when the coolant was last changed so decided i will do it this week.

Already got a can of the more expensive pink OATS type anti freeze then thought while i am at it i ought to look at the heat exchanger and check that is nice and clear does anyone know what size diameter the internal tubes are as she is currently afloat, so easier to take stuff with me than coble something together onboard.

Thanks in advance
 
chrishscorp said:
Already got a can of the more expensive pink OATS type anti freeze then thought while i am at it i ought to look at the heat exchanger and check that is nice and clear does anyone know what size diameter the internal tubes are as she is currently afloat, so easier to take stuff with me than coble something together onboard.
Click to expand...

There are several warnings around advising not to mix OAT and glycol antifreezes, they react to create a gel.
So it would be sensible to check what is already in the engine, if it is glycol then ensure you flush the system through well before adding the OAT antifreeze.
 
The recommendation from Beta is to take apart the heat exchanger and clean the tube stack annually, and in doing this you'll need to drain the majority of the coolant. I would therefore stick with cheap and cheerful glycol based antifreeze, as you'll be changing most of it each year. Do check what is in there currently, though, and don't mix different types.

I find a straightened out length of wire coat hanger works well for cleaning out the tubes, and it is recommended to use new O-rings when reassembling the heat exchanger.
 
alahol2 said:
There are several warnings around advising not to mix OAT and glycol antifreezes, they react to create a gel.
So it would be sensible to check what is already in the engine, if it is glycol then ensure you flush the system through well before adding the OAT antifreeze.
Click to expand...

An urban myth I suspect as I've never had any problems when I've mixed types. However, if draining the system rather than topping up then I would indeed flush through at least once with clean (soft if possible) water. In practice I find that it takes 2 or 3 flushes to get the old coolant plus crud out.

There will be a litre or three left in most systems unless you bother to drain down calorifiers etc so you need to look up the total capacity + calorifier in the handbook - say 8 litres - then add 4 litres of concentrated OAT to the system before topping up with clean water and then filling the expansion tank with 50:50.

The reason I don't ever buy pre-diluted antifreeze is that after an incomplete drain-down (which is the usual case) it's impossible to get the concentration in the system up to 50:50 so you have to settle for a higher dilution.

Richard
 
Minchsailor said:
'Dowty' washers (metal with a rubber insert) make a better seal, and are more reliable. Seem to remember they are 8mm
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The O rings in question are about 70mm. dia. Use of Dowty wahers isn't applicable.
Are you referring to the through bolt holding the ends, although I think this design has been superceded and now uses 3 screws.
 
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Sorry - I was getting my 'O' rings mixed up. There are the big O rings to seal the end caps to the heat exchanger body. These should be renewed. But there are also sealiing washers under the clamping bolts securing the end caps. After I serviced mine I had problems with these leaking. These are the seals I am referring to.
 
Kwik Decision said:
The recommendation from Beta is to take apart the heat exchanger and clean the tube stack annually, and in doing this you'll need to drain the majority of the coolant.
Click to expand...

Depending on running hours, type of strainer used and waters sailed in, I think it might well be unnecessary to do this annually.
I have settled on only doing it every second year (engine run approx 50 hrs/yr) and there has never been any severe clogging of the tubes.
Also, this is on a pre 2011 engine and most of the clogging that does occur is due to the zinc anode disintegrating. On the newer Beta engines (three bolt end caps) the zinc sits on the outlet of the heat exchanger, so this problem should be even smaller.
Still if you want to check every year, there is nothing wrong with draining the anti freeze a bit (enough to get the tube stack out) and then reuse it for another year.
 
Thanks for all the replies

Engine already has OATS in it so new stuff should be fine, yes hoping to get hold of some soft water to dilute the neat anti freeze.
I do have a spare anode which i was going to swap over and i think there are a couple of spare O rings the correct size on board but not sure how old so o rings and bolt washers are on the shopping list.

Hydrzoan, the colour piccy of heat exchanger on the spares list was really helpfull, kiddies pipe cleaners on shopping list as well, i reckon they will be the right size.
 
chrishscorp said:
... I do have a spare anode which i was going to swap over and i think there are a couple of spare O rings the correct size on board but not sure how old so o rings and bolt washers are on the shopping list.

Hydrzoan, the colour piccy of heat exchanger on the spares list was really helpfull, kiddies pipe cleaners on shopping list as well, i reckon they will be the right size.
Click to expand...

Glad it was helpful. BTW, I would not acid wash the tubestack (which some have suggested elsewhere) unless it's very badly scaled, as you'll just expose fresh metal and increase anode consumption. Pipe cleaners should be fine - I've only ever found bits in the tubes once, after an impellor broke up, and I had to raid the galley for the skewer - which is why I used them as a reference! I use Beta's big O-rings but just ordinary ones from a mixed stock for the bolts (old style of course).
 
alahol2 said:
Possibly, though here is at least one manufacturer that cautions against mixing [OAT and glycol coolant]... www.miller-bradford.com/employee-downloads/pdf/flyers/MBR-OATCoolants-ts-FINAL-MHR.pdf
Click to expand...

Is that the one that also cautions?:
Only use machines with chemical resistant hosing. OAT coolant will react with PVC, rubber and Viton seals, creating leaks over time.

Regarding gelling (and other properties) it needs to be acknowledged that OAT antifreezes use varied chemistries, particularly in their various additives. Bottom line, surely, as to read the spex of whatever brand is under consideration.
 
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Anti freeze changed even used deionised water, changed the anode, which i dont think had ever been done and cleaned the heat exchanger and found the remains of an impellor so well worth doing. Heat exchange pipes were smaller in diameter and more numerous than expected but pipe cleaners were brilliant for getting out the little bits of rubber.

Another job ticked off the list, thanks for the help
 
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