Beta 35 questions (Cooling system)

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Samosun

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Hi,

- Can anyone confirm that the connector shown below should not be connected to anything?

I've checked the wiring diagrams in the manual and it does seem the "COOLANT SWITCH/SENDER" (which I assume this is?) only has one wire going to it unless it is the "INSULATED EARTH RETURN" version. I take it the normal version uses the engine itself as the negative. I just want to check as the schematic diagram shows a switch with only 1 connector.....and this has 2.

beta 35.png

- Secondly, Do these engines have a fresh water pump? I've searched through the manual and cannot see mention of one anywhere. I take it if there is they almost never fail?

Thanks.
 
I mean freshwater pump. There is a seawater pump..... and a heat exchanger but no sign of what moves the fresh water/coolant around the engine.
 
I have a Beta 35 - the manual shows that from May 2005 the water temperature sender has been single pole.

The engine cooling water pump is a conventional type fitted to 'normal' engines and is unlikely to be a problem and should not require servicing - just like your car's.
 
Minchsailor said:
I have a Beta 35 - the manual shows that from May 2005 the water temperature sender has been single pole.
Click to expand...

The manual for my Beta 722 says (for engines before 2005) the larger terminal is for 'sender' and the smaller for 'switch'.
So presumably the larger should be used for a temp gauge and the smaller for a temp alarm.
 
Thanks for the water pump info! Good to know where it is.

Mines pre 2005. So that would explain the two pins. BabaYaga are you saying the smaller connector is basically just the binary overheat buzzer and the large one is analogue for an actual temperature reading? I wouldn’t mind having an actual temperature gauge....
 
Oh and I assume from what your saying neither are critical for running the engine, just for letting you know if it is overheating. These don’t connect to or contain any type of valve/thermostat?
 
Samosun said:
are you saying the smaller connector is basically just the binary overheat buzzer and the large one is analogue for an actual temperature reading?
Click to expand...
That's my understanding from the manual. My engine dates from 2005, but I'm unsure if there is one or two terminals. Only a buzzer on the panel, though.

Second question: I think so, but om my engine the temp sensor is in another location, on the cylinder head. Possibly the Beta 35 has more than one temp sensor?
 
The second pole on that sender is the NC side of the sender.

Fresh water pumps are pretty reliable assuming the alternator belt is not overtightened. Will likely last circa 10000hrs (Last one I changed on a kubota was 22000 hours run.)
 
Beta fitted a dual pole sender irrespective of whether the purchaser chose to have a temperature guage. The spare terminal is the guage contact and the one with the wire attached is the alarm terminal.

It's not quite as simple as you would imagine to add a temperature guage as the resistance/temperature profile of the sender has to match the guage. The ones fitted by Beta were Murphy and if you put a Vdo guage on this it will over read and suggest your coolant temperature is about 95-100C - well that's what happened with mine. This winter I have replaced the sender with a VDO one but lockdown prevents it being tested.
 
Thanks all for the info. Sounds like my main concern of something missing is unwarranted.

Interesting points Amlov, I might look into a separate gauge myself. Something like this:
Ebay - Boat Temperature Gauge
Would be pretty good but my coolant pipes are just a smidge smaller than 38mm ;)
 
Sorry to drag up an old thread, but I have the final piece of information to complete it.

The issue was the OP has a Beta Marine engine that has a water temperature sender with two contacts. One of the contacts being identified as the alarm and the other an output for a temperature gauge. It was then pondered whether it would be a simple task to fit a temperature gauge, as the engine didn't come with one.

The issue is that Beta fitted a Murphy temperature sender and it was postulated that it would not be directly compatable with gauges made by other companies, such as VDO. The reason being that they have different resistance:temperature profiles.

A few years ago, I fitted a VDO View line temperature gauge to my Beta engine using the existing Murphy sender. Under normal operation it read 90 degrees, increasing to close to 100 degrees when the engine was being pushed a bit. At the time, a thermometer suggested the engine was at about 70 degrees.

This winter I have fitted a VDO sender and now my VDO gauge reads 70 degrees increasing up to about 80 degrees when the engine is being pushed a bit. These are the sort of figures I would expect with an 80C thermostat.

I can therefore confirm that the gauge and sender need to be matched profiles to operate correctly and you can't easily mix and match.
 
Thanks Amlov, interesting info. Definitely something I'd consider doing too. Would you be able to share the products you bought which worked? What's the thread on the VDO sender?

Have you now lost the overheat alarm buzzer by changing the sender?

Thanks.
 
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