All_at_Sea
Active member
I need to remove the alternater for a service/change and may need to move the boat in the mean time. Any problems with running the engine without the alt wired into the system?
Running engine without alternater
- Thread starter All_at_Sea
- Start date
VicS
Well-known member
No problem from electrical point of view, apart from not charging the battery.
Make sure you insulate the connections though.
Nothing else eg coolant pump, driven by the same belt ?
All_at_Sea
Active member
doh!
Nothing else eg coolant pump, driven by the same belt ?
Very good point, l'll go check.
Nothing else eg coolant pump, driven by the same belt ?
Very good point, l'll go check.
Billjratt
Active member
Definately need the pump if its a freshwater cooled engine with a heat exchanger. Possibly fitting a smaller/ emergency-type belt would do the job if the route between the two pulleys is clear.
prv
Well-known member
Yes - although there are plenty of engines (mine included) where the alternator is on its own belt with the pump either on a separate one or driven directly. No problem popping the alternator belt off for me.
Pete
VicS
Well-known member
BUT
even if there is an engine coolant pump driven by the same belt you'd able to run the enigne for a ( good) few minutes without the coolant being circulated if its only to move the boat a short distance, between marina berths or to another nearby mooring for example.
even if there is an engine coolant pump driven by the same belt you'd able to run the enigne for a ( good) few minutes without the coolant being circulated if its only to move the boat a short distance, between marina berths or to another nearby mooring for example.
prv
Well-known member
My exhaust hose wouldn't thank me for trying that.
Might be ok on a freshwater-cooled engine if the seawater pump is still running to cool the exhaust. But don't most of these drive the freshwater pump with a shaft (as it's part of the base industrial or automotive engine) and the seawater pump with the belt?
Pete
All_at_Sea
Active member
Water pump
Mine is driven by the same belt so l will take it off and leave the boat until the alternater if fixed.
Thanks all.
Mine is driven by the same belt so l will take it off and leave the boat until the alternater if fixed.
Thanks all.
Sultans_Kapitein
RIP
Or you could go to Halfords and get an emergency fanbelt to put around the bits you still need, or if you remember the old 'get you home' trick a pair of ladies stockings will do as a temporary drive belt
Mal
theoldsalt
Active member
I think most indirect engines are the other way round. The fresh water pump is driven by the "fan belt" and the raw (salt) water pump is direct shaft driven. That's the setup on my Thornycroft T80.
Last edited:
Colvic Watson
Well-known member
Same on our Thornycroft 230
theoldsalt
Active member
This setup may be as a result of the marinisation of a vehicle engine rather than an original marine engine.
The fresh water is circulated around the cooling jacket of the engine using a vane pump driven by a belt. It is a vane (non positive displacment) pump as the flow will vary as the thermostat opens and closes to maintain water temperature.
The raw water pump however is usually an impeller (positive or fixed displacement) pump shaft driven as water flow though the heat exchanger is required to be dependant on engine speed. Because this pump is fixed displacement the water discharge flow should not be restricted as very high pressures can be generated. Also the supply flow should not be restricted as this causes a vacuum resulting in the collapse of the inlet pipe.
The fresh water is circulated around the cooling jacket of the engine using a vane pump driven by a belt. It is a vane (non positive displacment) pump as the flow will vary as the thermostat opens and closes to maintain water temperature.
The raw water pump however is usually an impeller (positive or fixed displacement) pump shaft driven as water flow though the heat exchanger is required to be dependant on engine speed. Because this pump is fixed displacement the water discharge flow should not be restricted as very high pressures can be generated. Also the supply flow should not be restricted as this causes a vacuum resulting in the collapse of the inlet pipe.
Pagetslady
Active member
My volvo 2003 is fresh water and the circulating pump is driven by the same belt as the alternator and the raw water pump is driven off the end of the camshaft,
Mike
Mike
VicS
Well-known member
Thats the sort of set up I had in mind when I referred to the "coolant pump", A common arrangement on Volvo and other makes of engine.
However it is possible for the seawater pump to also be belt driven.
Taken me a few moments to find an example but Thorneycoft 90 and 108 engines have a belt driven salt water pump. However in these it it is driven by a separate belt from the alternator and fresh water pump.
Almost all combinations are possible I guess
theoldsalt
Active member
VicS,
I stand corrected, setup variations seem to be common.
I stand corrected, setup variations seem to be common.
VicS
Well-known member
Yes. I think the most unlikely thing will be a directly driven fresh water pump,
but someone will be along shortly to name one!
awol
Well-known member
I ran my Yanmar with a belt made up of cable ties while the alternator was out. Wouldn't recommend it long term but it did the job for a couple of in/outs.
charles_reed
Active member
I think you'll find the raw-water pump is driven by a separate belt assembly - it's intended to work @ 100s rather than 1000s of rpm.
The suggestion of running for a "short time" is probably specious, unless <5 mins, you'll definitely risk head distortion without pump assistance for the engine coolant.
I had a number of cars (Austin 7s and Alvis 12/60) which had a genuine thermo-siphon system, but they were designed before 1930.
prv
Well-known member
Erm, that's exactly what I said. And turned out to be wrong anyway
What do I know, my engine's seawater cooled, I only have the one pump to worry about
Pete
Captain Sillyboxes
Member
Hi I thought I'd resurrect this thread instead of starting a new one. Last weekend I ran my engine (yanmar 2YM15) for 11 hours continually as we crossed Lyme Bay in flat calm conditions. Just as we were coming into port it started making the continual high electronic beep it does when it is unhappy and all the warning lights came on.
I switched it off, dropped the anchor, had a look and saw that the alternator belt was broken. To my shame I was not carrying a spare but luckily I managed to get a tow in.
On this engine, the belt that drives the alternator doesn't drive anything else so according to this thread, once I'd ascertained the cause of the problem I guess I could've ignored the warning sound and lights and completed the trip under my own steam.
But my main question is, is it normal for alternators to just snap like this? It's only two seasons old. Is this just the sort of thing that happens from time to time, it could it be my engine's way of telling me about a more profound problem?
I switched it off, dropped the anchor, had a look and saw that the alternator belt was broken. To my shame I was not carrying a spare but luckily I managed to get a tow in.
On this engine, the belt that drives the alternator doesn't drive anything else so according to this thread, once I'd ascertained the cause of the problem I guess I could've ignored the warning sound and lights and completed the trip under my own steam.
But my main question is, is it normal for alternators to just snap like this? It's only two seasons old. Is this just the sort of thing that happens from time to time, it could it be my engine's way of telling me about a more profound problem?