Beta raw water inlet size

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syvictoria

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Hi. Beta Marine used to state that a 1 inch raw water inlet was required to ensure sufficient throughput (although I know some people get away with smaller). The current manual now states that for Beta 10-38, the Seacock Inlet/Seawater Engine Pump Hose I.D minimum is 19 mm. Furthermore, the manual goes on to quote that the sea water flow should be 13 - 14 litres/minute minimum at 1,500 rpm, whereas the older manuals stated 15 L/min.

Can anyone confirm please, has there been a fundamental/physical change to the engine/raw water pump to cause this change, or have Beta simply tempered their requirements, maybe in light of evidence in the real world?

Many thanks.
 
syvictoria said:
Hi. Beta Marine used to state that a 1 inch raw water inlet was required to ensure sufficient throughput (although I know some people get away with smaller). The current manual now states that for Beta 10-38, the Seacock Inlet/Seawater Engine Pump Hose I.D minimum is 19 mm. Furthermore, the manual goes on to quote that the sea water flow should be 13 - 14 litres/minute minimum at 1,500 rpm, whereas the older manuals stated 15 L/min.

Can anyone confirm please, has there been a fundamental/physical change to the engine/raw water pump to cause this change, or have Beta simply tempered their requirements, maybe in light of evidence in the real world?

Many thanks.
Click to expand...

FWIW, the manual for my Beta 722 manufactured 2005 states that the inlet sea cock and pipe work 'should be 22mm ID or 3/4" minimum'.
Since 22mm is an awkward size, I used 19mm (3/4") for the inlet and I have had no over heating problems.
However, pipes on the engine further down stream the cooling system were 22mm, for instance the hose connecting the heat exchanger to the exhaust bend. So I had to source some 22mm ID hose, as I needed to install an anti-siphon valve here.
When I wanted to replace the exhaust bend a few years ago, it was no longer obtainable with 22mm connection, only with 25mm (1").
My interpretation of all this is that Beta thinks 19mm is a bit marginal and 22mm would be ideal, but because fittings for 22mm ID are rare they use a mix of 19 and 25mm.
 
Thanks so much for your reply BabaYaga. That was exactly our thinking when we, after much head scratching, opted for a 3/4in inlet. Our engine (and manual!) date from 2013. However, we have actually only just commissioned the engine and much to our disappointment, we are experiencing over heating issues - and we haven't even left the dock yet! :mad:

We've installed the engine ourselves and there have been absolutely no other issues whatsoever so far. The engine starts on the button, it's not using or losing any fluids at all, and it purrs along beautifully when in neutral or in gear tied up. Initially it was overheating quite quickly (after just 10 minutes or so), but after a thorough cleaning and flushing through of the both the raw and freshwater systems, and refilling with fresh coolant (30/70 coolant to water as that's all we had available), it now runs for longer (about 20+ mins) before the dreaded alarm sounds. There was a lot of sediment in the engine and the drain tap was blocked, etc. - all the normal problems that are reported widely in these forums, and all now sorted. We've ran bucket tests from the dinghy - 14/L/min. The exhaust system is all new and has an anti-siphon loop, Vetus waterlock (upright model) and swan neck. The angles are, we think, all correct. We have no idea how to test back pressure (also mentioned in the manual). The impeller is fine. The thermostat performs as expected when bucket tested. What on earth is causing our problem? We're mystified... and infuriated! We had desperately hoped to move closer to home now that we are finally actually afloat, but it looks like we might be back on the hard at Burnham for another winter... :sorrow:

I haven't yet contacted Beta. I'm not sure that they'll want to offer too much support this far down the line... and I can't say that I'd blame them.
 
Since I have had none, my experience of over heating problems is very limited.
But from your description, measuring 14 l/min in the bucket, I would forget the sea water side and concentrate on fresh water circuit – still sediment, air locks ? etc
Or possibly, faulty alarm?
 
As a further test, we've just ran the bucket test from buckets (if that makes sense!), thereby ruling out the thru hull and water strainer parts of the equation, and we get the same throughput. That's something of a relief. The water inlet hose is 19mm ID and the anti-syphon loop/vent uses 25mm ID hose.

We don't think we have any air locks. We did have initially, but we have since learnt about the bleed screw in the thermostat housing and on refilling the freshwater side we ensured that the thermostat housing was full (that's our highest point) and we have since bled the system from the bleed screw a couple of times. There is no coolant being expelled when overheating which suggested that there are no hot spots/airlocks in the system I believe?

Faulty alarm... I don't know. The thermostat housing is showing an external temp of about 100 degrees C when the alarm sounds.
 
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Having just looked again at our exhaust system, we are now wondering whether the cause of the problem may be the Marelon valve that we have on the exhaust thru hull. The valve was an impromptu purchase at a boat jumble and it has right angle hose tail connection. Could this be causing a back pressure problem? Otherwise, the exhaust system is all straight with one large loop (swan neck) just before it joins the valve.
 
Pye_End said:
Can you explain this?

Also, when under load, what max rpm are you getting?
Click to expand...

Hi. We tested the thermostat in a bucket of warm water several times, adding hot until it opened at, or very shortly after, the marked temp of 71 degrees C. I believe this proves that it's functioning correctly? It was definitely fully open by 80 degrees C.

Since we've ran all tests whilst moored up, we haven't yet experienced anything close to full rpm! Mostly we've been running at 1,200-1,500 rpm.
 
Why don't you ask Beta, they are very helpful. I'm just installing a Beta 43 and I have put in a bigger skin fitting to comply with the 25mm ID minimum. Definitely not something worth skimping on in my view. It would also invalidate the guarantee if it was too small..don't know if that applies to you.
 
syvictoria said:
....
I haven't yet contacted Beta. I'm not sure that they'll want to offer too much support this far down the line... and I can't say that I'd blame them.
Click to expand...



I think it is very wise not to contact manufacturers until you have weighed the job up in detail. Getting onto the forum clarifies your ideas, can often solve the problem and may well offer up a few unrelated tips and useful info.
It also means if you won't be fobbed off with the typical nonsense which is often dished out when you ring up suppliers.

I have found Beta to be a happy exception to the normal attitude so I think, in the end, it will be well worth a call. Ask about the warranty which (when I last looked) is now up to 5 years. More importantly, I think there is a waiver on engines that are bought, installed but not commissioned for some time; you may find you should have registered in advance but worth asking. I am not suggesting this is a guarantee issue.

Any road when you have exhausted all else worth a punt.
 
Ohlin Karcher said:
Why don't you ask Beta, they are very helpful. I'm just installing a Beta 43 and I have put in a bigger skin fitting to comply with the 25mm ID minimum. Definitely not something worth skimping on in my view. It would also invalidate the guarantee if it was too small..don't know if that applies to you.
Click to expand...

Sorry, I should have clarified that I only have a Beta 25 and, as mentioned previously, a 19mm ID should (according to current spec.) be sufficient. I appreciate that a 1in might be 'better' but space for fitting water strainers, etc. all had to be taken into account when we made the decision to go with 3/4 in.
 
From what you say then it sounds like the seawater circuit is functioning so perhaps the coolant circuit is not working (either blockage in the circuit or the coolant pump (not the seawater one) is not functioning properly). You mentioned a lot of sediment and the block drain tap being blocked, which would be in the coolant circuit. Was the engine new in 2013 or second hand? Sediment is usually from metal corrosion or rubber bits degrading. Insufficient or old antifreeze/inhibitor in your engine would not help if it's been standing there for 6 years with it in the cooling circuit. Pressure flush the coolant circuit and check the coolant pump. I also understand a faulty radiator cap can cause over heating by letting air pockets get into the circuit so maybe the first thing to check. Finally, do you have calorifier running off the engine? Apparently they can cause overheating if the coolant flow through it is not restricted enough (presume it can reduce coolant flow through the block somehow). If you do, can you isolate it to see?
 
neilf39 said:
From what you say then it sounds like the seawater circuit is functioning so perhaps the coolant circuit is not working (either blockage in the circuit or the coolant pump (not the seawater one) is not functioning properly). You mentioned a lot of sediment and the block drain tap being blocked, which would be in the coolant circuit. Was the engine new in 2013 or second hand? Sediment is usually from metal corrosion or rubber bits degrading. Insufficient or old antifreeze/inhibitor in your engine would not help if it's been standing there for 6 years with it in the cooling circuit. Pressure flush the coolant circuit and check the coolant pump. I also understand a faulty radiator cap can cause over heating by letting air pockets get into the circuit so maybe the first thing to check. Finally, do you have calorifier running off the engine? Apparently they can cause overheating if the coolant flow through it is not restricted enough (presume it can reduce coolant flow through the block somehow). If you do, can you isolate it to see?
Click to expand...

Thanks for help and suggestions. The engine was new in 2013. We haven't pressure washed the system, but we have flushed through lots of water from various points until everything ran clear. The pressure cap certainly seems to be okay, and no coolant is being expelled via the overflow even when overheating, which I think means that there aren't any air locks/hot spots in the system? Coolant was being expelled in quantities when we did initially have an air lock at the thermostat (before we manually filled the housing and bled the system properly upon refilling with new coolant). All the fluids were new in July, with coolant having again been replaced this week.
 
Would have thought back pressure would only show as an issue with higher rpm.

If you run it up to max and get near 3600 it would show that there is not an undue load on the engine (eg over propped, foul propped, stiff sterngear etc) - not that this would be at all expected given your circumstances. No idea if too much back pressure will stop the engine from reaching full rpm, but sounds plausible.

Fresh water circuit - did you get water out of the drain plug at the bottom? Just wonder if there is still a restriction from crud in this part of the circuit (ie the other side of the thermostat).
 
syvictoria said:
Yes, all cleaned. New O-rings fitted.
Click to expand...

When you say "all cleaned", did you take the heat exchanger stack out completely and checked both sides (saltwater and coolant water side) to be clean? Our Beta was overheating and it turned out to be the coolant side of the heat exchanger completely covered in something (probably limescale from filling with tap water). You could only see it, once the tube stack came out of the housing.
Days bathing it in lime scale remover cleaned it up again. Everything was fine after that.
 
syvictoria said:
Hi. Beta Marine used to state that a 1 inch raw water inlet was required to ensure sufficient throughput (although I know some people get away with smaller). The current manual now states that for Beta 10-38, the Seacock Inlet/Seawater Engine Pump Hose I.D minimum is 19 mm. Furthermore, the manual goes on to quote that the sea water flow should be 13 - 14 litres/minute minimum at 1,500 rpm, whereas the older manuals stated 15 L/min.
Click to expand...

Heating 12.5 litres per minutes of water through 60oC takes 52.5kW, which is 70hp. Given that small diesels are typically 33% thermally efficient, I'd expect that flow to be fine for anything up to 35hp of thereabouts.
 
Thanks for the further replies. Yes, the drain plug is unblocked (which took quite some doing!) and the tube stack has been completely removed and it and the housing thoroughly cleaned.

We've now spoken to Beta and they still suspect a blockage in the freshwater side. We have consequently flushed the whole system through again a further three times today with freshwater, and we've been surprised to find that crud is still periodically being expelled! The last flush came out all but clear and so we have new antifreeze to add again tomorrow. Finger's crossed!

Thanks for the calculations JumbleDuck. That's reassuring.
 
A question regarding the coolant drainage tap... Do you (other Beta owners) manage to drain the system completely via the tap? We get about 300ml and then it stops draining. The remaining coolant we have to let out via the front hose and/or pump out via the fill cap. Should we therefore conclude that we still have a blockage at the tap end of the system which needs to cleared? Can anyone confirm how the tap can be accessed from above? We have poked wire in and round the elbow, from below (and water flows freely when poured in the thermostat housing, but not from the heat exchanger) and so there could still be a blockage/sediment above this that we can only clear from the other direction. Surely all 3.25L of coolant should drain out the tap when opened with the filler cap off? I hope that makes sense! Many thanks.
 
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