Using electric pump for raw water pump

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Pagetslady

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hi I have a new Beta 35 engine on my boat, I have had cooling problems since installing it January 2013. It runs fine as long as I do not exceed 2000 rpm which gives me a reasonable cruising speed but if I run at 2500 rpm for long the temp rises to 100c max revs is 2800 rpm. I have followed all the advice from Beta which they very helpfully give. I have checked the water flow leaving the exhaust and found that this is not as much as Beta say it should be, but I have checked out the Pump specifications and find that the pump delivery rate is in fact less than Beta specify it should be at the exhaust. I was wondering if the simplest thing to do to test it would be to use an electric pump rather than the mechanical pump? I assume the pump would need to take its 12v power supply from the alternator somehow possibly with a relay actuated by the alternator taking the source power from the engine battery, this would make sure the pump only pumps water when the engine is running. I intend in the new year to arrange for the local Beta engineer to come to Fleetwood and check out my installation and come out for a run in the bay to see what he thinks is the problem if in fact I have one. Unfortunately soon after installing the engine when out on test I had an over heat alarm and found that the header tank cap and the tank cap fitting were faulty and the cap had been blown off, Beta did accept that this was faulty and supplied a new cap and fitting, and several spares as compensation but unfortunately this did not install a great deal of confidence, having changed my faithful old VP 2003 due to several years of cooling problems. The new engine has now done 200 hrs so I would like to sort it out soon as I plan to go south to Jersey and Brittany in 2015.
Regards Mike
 
You should really not have that sort of problem on a new engine. There must be something limiting the flow of raw water through the heat exchanger. Typical things are undersize inlet, air getting in the system, defective impeller or blockage in the heat exchanger. The standard pump is quite capable of delivering the correct flow so no need to supplement it with an electric pump.

The header tank problem is a red herring as that is in the freshwater circuit which has no effect on the raw water flow. So concentrate on finding why the raw water pump is not delivering the correct volume.
 
If the engine has been like it since new and you had a similar problem on the former engine I would guess that the inlet is too small. Maybe the inlet seacock isn't opening enough or the internal dimension is smaller than normal, kink in the inlet hose?
 
I concur with the 2 post above, sounds like you have a problem with the water supply to the pump. Is the seacock working/opening properly? Just because the handle turns, it doesn't mean the ball is opening fully.
 
Why not by-pass the raw water inlet using a hose pipe into a water container and with the inlet pipe taking water from the container. I did this after I bought my boat with an engine fault and it was in a cradle. After fixing my engine I was able to run it up to operating temperature and ran it for over four hours.
By passing the inlet will identify whether or not it is operating properly, when you get the Beta Engineer down he will need to know that you have ruled out the seacock being faulty.
 
My first reaction is that the problem is either:
a legacy of the old installation, specifically the raw water plumbing, as mentioned, in which case it's for the OP or possibly installer to fix;
or something intrinsic in the new engine, in which case it's for the engine supplier to fix.

Jim@sea's suggestion should help confirm either way.
I'm assuming it's not something as obvious as a partially blocked intake strainer.

And a very merry Christmas to all.
 
When I upgraded from a Bukh 20 to a Yanmar 27 it was necessary to increase the size of the inlet seacock from 1/2 to 3/4 inch. The engine was replaced afloat, leaving the seacock change until the end of the season. There was some evidence that the Yanmar ran hot in the remainder of the season, although not drastically, overcome when the seacock was changed.
 
Pagetslady said:
hi I have a new Beta 35 engine on my boat, I have had cooling problems since installing it January 2013. It runs fine as long as I do not exceed 2000 rpm which gives me a reasonable cruising speed but if I run at 2500 rpm for long the temp rises to 100c max revs is 2800 rpm. I have followed all the advice from Beta which they very helpfully give. I have checked the water flow leaving the exhaust and found that this is not as much as Beta say it should be, but I have checked out the Pump specifications and find that the pump delivery rate is in fact less than Beta specify it should be at the exhaust. I was wondering if the simplest thing to do to test it would be to use an electric pump rather than the mechanical pump? I assume the pump would need to take its 12v power supply from the alternator somehow possibly with a relay actuated by the alternator taking the source power from the engine battery, this would make sure the pump only pumps water when the engine is running. I intend in the new year to arrange for the local Beta engineer to come to Fleetwood and check out my installation and come out for a run in the bay to see what he thinks is the problem if in fact I have one. Unfortunately soon after installing the engine when out on test I had an over heat alarm and found that the header tank cap and the tank cap fitting were faulty and the cap had been blown off, Beta did accept that this was faulty and supplied a new cap and fitting, and several spares as compensation but unfortunately this did not install a great deal of confidence, having changed my faithful old VP 2003 due to several years of cooling problems. The new engine has now done 200 hrs so I would like to sort it out soon as I plan to go south to Jersey and Brittany in 2015.
Regards Mike
Click to expand...
I have the Nanni 37.5 which i think is the same 4 cylinder 1500cc engine. it is 11 yrs old done 1100hrs & has never overheated.
what size is your skin fitting, it could be too small a dia.
When i re engined i didnt change the inlet as the old engine was a Perkie 4108 & if the water flow was ok for that engine is was certainly good for a engine smaller by 200cc
 
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Thanks everybody, all the above have been checked the flow through the 25 mm seasick and hose is all new and the flow to the pump is way more than is needed the heat exchanger has been cleaned and new impeller installed. I am aware the header tank problem has nothing to do with this problem but it was the last thing I needed the first time out with the new engine. The point I did however make was that the capacity of the raw water pump is not high enough to produce the required flow at the exhaust, but I failed to mention that I have no way of checking the accuracy of the temp gauge. I have an thermometer gun but am not sure where to check the temp and how much it should read.
Mike
 
I cant believe the engine manufacture would supply an engine and water pump combination that fails to cool the engine, therefore its mostly likely.

faulty installation

water system partial blockage

damaged impellor

faulty temp gauge

I would start with the temp gauge, find some means of checking the temp.
 
First thing to check would be the sender resistance and if it is matched with the gauge. (not all senders are the same resistance). Remove the sender wire from the sender before checking the resistance. With a multimeter set on low resistance place the probes on the block and top connection of the sender. Manufacturers will have a table of resistance at varying temperatures to compare with.

Then in a controlled test remove the sender from the block, connect an earth wire to the outer case of it and back to the engine block. Reconnect the sender wire and carefully place the sender into a cup/mug of boiling water, with the ignition switch on (do not start the engine) what does the temperature gauge read.

This can all be done whilst tied up on the mooring.
 
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Big John said:
First thing to check would be the sender resistance and if it is matched with the gauge. (not all senders are the same resistance). Remove the sender wire from the sender before checking the resistance. With a multimeter set on low resistance place the probes on the block and top connection of the sender. Manufacturers will have a table of resistance at varying temperatures to compare with.

Then in a controlled test remove the sender from the block, connect an earth wire to the outer case of it and back to the engine block. Reconnect the sender wire and carefully place the sender into a cup/mug of boiling water, with the ignition switch on (do not start the engine) what does the temperature gauge read.

This can all be done whilst tied up on the mooring.
Click to expand...

Hanks for that Big John I will check it out soon.
 
Is a hose collapsing between seacock & RW pump inlet @ hi rpm? You must use "suction" rated hose (usually wire wound) on suction line.
Is the RW filter leaking air,or otherwise restricting flow?
To test,run engine up to 3000 rpm @ dock,in neutral.
Remove RW pump outlet hose & route it to a container.
Run engine up to 3000 rpm,in neutral,at the dock, & check flow for 15sec. Multiply x 4 for gal/Ltr / min.
Is the RW impeller install backwards?

Cheers / Len
 
Len Ingalls said:
Is a hose collapsing between seacock & RW pump inlet @ hi rpm? You must use "suction" rated hose (usually wire wound) on suction line.
Is the RW filter leaking air,or otherwise restricting flow?
To test,run engine up to 3000 rpm @ dock,in neutral.
Remove RW pump outlet hose & route it to a container.
Run engine up to 3000 rpm,in neutral,at the dock, & check flow for 15sec. Multiply x 4 for gal/Ltr / min.
Is the RW impeller install backwards?

Cheers / Len
Click to expand...
I reversed mine 4 weeks ago when i serviced the engine
 
There's no such thing as an impeller being backwards. The blades on the impeller are bent over, as required, by the cam on the pump body.

Apparently, the previous owner of my boat had a similar problem, and eventually found that part of the suction hose, which wanders around cooling the gearbox etc, was delaminating inside. This was blocking the flow at higher revs.
 
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Big John said:
First thing to check would be the sender resistance and if it is matched with the gauge. (not all senders are the same resistance). Remove the sender wire from the sender before checking the resistance. With a multimeter set on low resistance place the probes on the block and top connection of the sender. Manufacturers will have a table of resistance at varying temperatures to compare with.

Then in a controlled test remove the sender from the block, connect an earth wire to the outer case of it and back to the engine block. Reconnect the sender wire and carefully place the sender into a cup/mug of boiling water, with the ignition switch on (do not start the engine) what does the temperature gauge read.

This can all be done whilst tied up on the mooring.
Click to expand...

On further thoughts if you used the old wiring, gauge etc. from your old VP engine you need to check the voltage regulator that controls the fixed voltage to the gauge. I think you said you had an overheating problem with the VP engine.

If the regulator is faulty or not there then you will see the gauge rise after a short while as the starter battery comes back up to full voltage as the alternator charges the battery.

You said in your first post that above 2500rpm the temperature went to 100c. What if you then dropped down to the 2000rpm did the temperature drop as well?
 
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