Beta Marine Engine Coolant Header Tank Expansion Pipe Blocked

CaptainBob

CaptainBob

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A boat I'm looking at buying has a "blanking cap on the engine coolant header tank expansion pipe" (my surveyor's words not mine).

Engine is a relatively recently installed Beta Marine. Not sure of the model.

Any ideas why it might be blanked off? Is this normal? Or a worry?

Thanks!
 
Surveyors in the UK dont have to have any qualification so some are very good and know what they are talking about, others dont. Find it difficult to imagine anything much to do with the header tank that could be a worry (in the context of the price of a boat, engine repairs are cheap) but ask your surveyor to explain. Thats part of his job and it should tell you whether he understands what he's looking at.
 
If you look at the line drawings for Beta Engines, they all have an expansion pipe connection just below the header tank cap. Normally you would expect a plastic pipe to be connected (on my Volvo I dangle the plastic pipe into a small plastic bottle to take any expansion). It is clear from the words used that this expansion connection is blanked off - ie not used which is strange. Curiously, the one thing that you read about on these forums regarding Beta is cooling issues. I would have thought it needed to be unblanked and free to breath (it only does so when the pressure rises sufficiently to life the pressure release part of the cap and thus escape).
 
Personally I think the surveyor is doing his job pointing out something to be investigated. See

http://www.betamarine.co.uk/newsite/downloads/handbooks/1590.pdf

You will see in the picture the clear plastic pipe running from the expansion pipe and numerous other pictures of it within the manual. I have only taken this one at ranom but I think they are all the same. Why don't you ring Beta?
 
As others have said, this small bore plastic pipe is to allow excess coolant to escape when the engine runs and the coolant is subject to thermal expansion. When the engine is switched off, the coolant contracts, and air is sucked up this pipe. It should definately not be blanked off, as this will cause excess pressure in the cooling system, and something will have to go.

Mine simply dangles down the side of the engine towards the bilge.

I suggest you get your surveyor to explain in some detail his comments, as he may be talking out of his fundamental orifice.

Please post his reply on here so we can all understand (hopefully!) what he is on about.
 
The surveyor is not talking out of his rear end as he is simply making an observation and not presenting CaptBob with an interpretation/solution (which they probably should have done). One would hope that he will give CaptBob some guidance as to how much of an issue this is if CaptBob asks. I would agree with others that this outlet should be unblocked and a bit of pipe attached, the other end placed at the bottom of a 500ml (approx) bottle so that vented liquid can be drawn back in when the engine cools.
 
Yeah, to be fair the surveyor has been spot on. He's sent me a preliminary list of issues with the boat prior to sending the final report, and has simply put a question mark on that, saying it _might_ be an issue.

I'm going to get him to confirm the exact location of this blanking cap, and get in touch with beta marine tomorrow if I can and try to find out if it's a problem or not.

Will keep you all posted as I find out more.

Thanks for the replies, much appreciated.
 
The overflow pipe on my Beta is just left open-ended and causes no problem. I would have thought blanking it is not the best option. Either open or, better still, into an expansion container would be better IMHO.
 
Looking at the Beta manuals on the Bluemoment website I can see the pipe in question and reading the cooling system filling instruction the last paragraph reads [ QUOTE ]
(h) Run the engine on one third load
for 15 minutes, preferably with
the boat tied up. As the system
warms up coolant may be
expelled from the overflow pipe
into the bilge. Stop the engine
and allow the engine to cool
down before removing the
pressure cap and top up the
coolant to 1” below the filler
neck.

[/ QUOTE ]

That implies that the pipe is open ended as one would expect and just routes any overflow to the bilges.

A small collection vessel to catch any coolant expelled as suggested is a good idea as it gives the opportunity to monitor any overflow.

The type of pressure cap shown on the cooling system appears to be the "conventional" type of cap used on many car radiators. They do not normally make a tight seal** on the top of the filler neck so capping the overflow pipe will not cause any problems except that any overflow will be over the engine instead of neatly routed to the bilges. It rather defeats the object of the overflow pipe though.

It would be interesting to discover why the previous owner capped it. It might just be because the pressure cap leaks a little or because he had a tendency to overfill the system.

The Surveyor has correctly noted something out of the ordinary but probably of no great significance.

EDIT

** and if it is like this it will not suck any expelled coolant back into the system from a collection bottle.
 
[ QUOTE ]

The type of pressure cap shown on the cooling system appears to be the "conventional" type of cap used on many car radiators. They do not normally make a tight seal on the top of the filler neck so capping the overflow pipe will not cause any problems except that any overflow will be over the engine instead of neatly routed to the bilges. It rather defeats the object of the overflow pipe though.



[/ QUOTE ]

Sorry to disagree with you, but these caps DO make a tight seal.

If you look at the Beta parts manual, part no 209-80130 (the cap in question) is described as "95kPa Pressure cap"

As I said earlier, when the coolant heats up and expands, it has to go somewhwere, and the cap lifts when the pressure reaches 95kPa. If the overflow pipe is blocked, then something else will blow, possibly a hose.

I'm still wondering what the surveyor means, as this hose should not be sealed under any circumstances.
 
[ QUOTE ]
Sorry to disagree with you, but these caps DO make a tight seal.

[/ QUOTE ] Perhaps you misunderstand.

The type which I think are fitted to the Beta engines make a pressure seal at the bottom of the filler neck, below the overflow. A valve with two components in fact. One to control the pressure to the specified value (they vary) and another which opens at a lowish negative pressure to allow air back in when the system cools.

At the top of the neck there is metal to metal contact but not normally any sealing washer to make a completely air and water tight joint. (I modified one once to make that an air and water tight joint for an engine which had some cooling system problem so that I could recover coolant expelled and have it automatically sucked back in when the system cooled.)

I don't doubt for one moment that the pressure cap has the rating you say it does but that is controlled by the spring loaded valve that seats at the bottom of the filler neck not by any thing at the top of the neck.

You have also tampered with that part of my post which you offer as a quote. I did not put any part of my post in bold type!
 
95KPa => 13.778 PSI - Allows the coolant to reach ~ 119°C before boiling. The main reason for the caps to lift and overflow (apart from serious overheating) is overfilling the header. Filling to the correct level leaves an air cushion to absorb the expansion of the coolant. The 95KPa rating refers to the pressure needed to lift the lower part of the cap off the bottom of the filler neck as Vic quite correctly stated. There may aor not be another thin "seal" under the cap top but that is not a pressure rated seal - it is there (if present at all) to divert water/steam into the overflow line and not over the engine.
---------------------
hammer.gif
Artificial Intelligence is no match for Natural Stupidity
 
Vic,

Yes, we misunderstood each other. I was referring to the seal between the tank and the cap at the bottom of the neck, while you were referring to the top of the cap above the overflow pipe, which I agree is not a seal.

That's one of the problems with discussions such as this, in that we both write what we percieve as being correct, then have to wait until the other person replies, and we still get it wrong! I'm sure if we had been face to face, then we would have soon sussed that we were talking about different things, and we were both correct in the bits we were discussing.

The only reason I put part of your quoted post in bold, was to indicate the bit my reply referred to.


Sorry if I've upset you, but it was not meant to in any shape or form.

I shall refrain from getting involved in discussions in future if I'm going to upset people.


Goodbye
Jim
 
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