Yanmar 3gm30f- calorifier not working after coolant change.

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fredrussell

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Was working fine before coolant change, and works fine on shore power. I’ve blown through send and return hoses from fresh water pump, checked thermostat is operating and there’s no crud in system (did flush with product before changing coolant).

Does the engine coolant get pumped through calorifier ‘coil’ or does heat just pass through it by convection? I ask as when I took one of the coolant pipes (to/from calorifier) off coolant pump housing there was no flow of coolant coming either from pump end of things or calorifier coil end of things. Do I need to prime or bleed calorifier? Any tips gratefully recurved.
 
Just to add. After running engine on idle for a good half an hour, I removed heat exchanger cap and coolant inside was stone cold. Is half an hour at idle not enough to open thermostat do you think? I assume calorifier coil only receives hot coolant after thermostat opens, correct?
 
The hot water is pumped through the calorifier and the heat exchanger by the coolant circulation pump. The H/E is after the thermostat but the calorifier could be before or after depending upon how it is plumbed in. You can follow the hoses to check this for yourself. However, if neither of the hoses to and from the calorifier are hot after 30 minutes, you have an air lock.

You needed to start checking fan belt tightness, feeling hoses, revving the engine, squeezing hoses, disconnecting hoses etc to clear the lock.

Richard
 
Cheers Richard. I’m a bit baffled by what’s flowing where with engine running to be honest. New to inboards so learning curve steep at the mo.
 
fredrussell said:
Cheers Richard. I’m a bit baffled by what’s flowing where with engine running to be honest. New to inboards so learning curve steep at the mo.
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No problem, Fred.

I would start with the easiest first which is checking the fan belt. If that's OK, look around to see if you have any large hoses which are soft enough to squash with your hand then start the engine at idle, and a bit faster, and keeping vigorously pumping all the soft hoses, one after another, and then feeling for the hot water to start circulating.

If that doesn't work, you probably need to consider removing hoses from spigots or removing the thermostat. Personally, I would try removing the upper hose from the calorifier and start the engine using bottles to collect any coolant. If nothing appears then try sucking on the spigot with a clear pipe so you can see the coolant appearing without swallowing any.

You shouldn't need to remove the main circulating hoses but such things can be done further on down the road.

Richard
 
It surprised me too. I’m down at boat this eve. I’ll try removing thermostat in case I hadn’t let engine heat up enough and then work through Richard’s suggestions.
 
fredrussell said:
I’m a bit baffled by what’s flowing where with engine running to be honest. New to inboards so learning curve steep at the mo.
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There is a description and diagram of the cooling system in the service manual (See Chapter 8) which you can download from Manual Downloads | Barrus

( Note the 1GM10 manual covers all the GM series engines, not just the 1GM10)

See also in the same chapter, section 6, an explanation of how the thermostat operates and controls the water flow through the internal bypass.
Don,t be tempted to run the engine, other than for diagnostic purposes, with the thermostat removed because the internal bypass will remain open, possibly leading to overheating. You may not get much hot water flow to the calorifier either.

I think you simply have not run the engine long enough for the water in the HE to become warm. No hot water flows to it from the engine until the thermostat stats to open.

I suspect you are getting no hot water flow to the calorifier because that part of the system is air locked but until the thermostat start to close the internal bypass not much water will flow that way in anycase.

Try running the engine for longer at a fast idle under some load, ie pulling against the mooring warps.

I don't think removing the t'stat will aid the diagnosis of your problem but it will give you an opportunity to test that it opens at the correct temperature by following the procedure described in the manual.
 
If you run your engine on idle for long periods you will bugger it up. See the many posts on here about clogged up exhaust manifolds. leaving it on idle particularly in this cold weather won't allow it to warm up properly. Put it into gear and make it work a bit
 
fredrussell said:
Was working fine before coolant change, and works fine on shore power. I’ve blown through send and return hoses from fresh water pump, checked thermostat is operating and there’s no crud in system (did flush with product before changing coolant).

Does the engine coolant get pumped through calorifier ‘coil’ or does heat just pass through it by convection? I ask as when I took one of the coolant pipes (to/from calorifier) off coolant pump housing there was no flow of coolant coming either from pump end of things or calorifier coil end of things. Do I need to prime or bleed calorifier? Any tips gratefully recurved.
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It sounds as if you airlocks the calorifier during the coolant change. Not unusual at all . All you need to do is to bleed the air out of the calorifier coil.

You may be lucky and find a bleed valve at the top calorifier coil inlet. If there is not one then with the engine running up to temperature and the coolant warming up slacken of the higher of the calorifier coil connections till water flows . You might have to repeat this process if it fails first time.
 
You've got air in the coolant hoses. Just start the engine with the coolant cap taken off. run the engine until the air bubbles are gone. Stop the engine, top up the system and repeat the process.
But be very careful, because the coolant gets very hot.
 
I have an old 4 cylinder bmc engine and after 20 mins everything is fairly hot, and warm water in the calorifier. As others have said , run engine in gear( gets hotter quicker) , check operation of thermostat.
It does sound like an airlock preventing proper circulation.
 
You will have two hoses - one feed and one return from the calorifier to the engine. Disconnect the engine ends of these hoses and position them so that one of the end is a little lower than the other. Use a funnel to pour coolent gently into the end of the higher hose. Coolant should trickle out of the lower one once the system is full. If it does not then you have an air lock which you need to push through with a water hose or separate pump.
One of the hoses may have a fitting which can be unscrewed with an allen key to allow filling at the highest point with the hose still connected. The fitting looks like a rubber disc at first glance. If this is present then undo the engine end of the other hose and fill from the fitting. I have thought about making a fitting to connect a hose pipe to this threaded fill point to allow me to really balst through the coolant system like a power flush but I have never got round to it. Let us know how you get on
 
Halo said:
You will have two hoses - one feed and one return from the calorifier to the engine. Disconnect the engine ends of these hoses and position them so that one of the end is a little lower than the other. Use a funnel to pour coolent gently into the end of the higher hose. Coolant should trickle out of the lower one once the system is full.
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This did it in the end. Cheers everyone.
 
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