Cleaning out cooling channels in engine

[Habebty]

I want to clean out the cooling passages and galleries in my Beta 20hp. Can I just put the raw water intake in a bucket of say...Furnox and let it suck this up until the bucket is empty and stop the engine ?
What is the best way to clean out the freshwater side of the system?
I usually just remove the heat exchanger pipe stack and rod it out but what other bits need doing?
Had a little bit of overheating when pressing the engine and suspect maybe some silt or whatever in the block .
Cheers

 

[VicS]

You seem to be confused about the differences between a directly cooled engine and an indirectly cooled one.

In the former sea water passes through the engine and can cause corrosion, scaling and deposition of solids . There is no heat exchanger involved.

In an indiectly cooled engine the engine itself is cooled by fresh water which should contain antifreeze or a corrosion inhibitor, just like your car engine. That water is circulated through a heat exchanger to be in turn cooled by sea water.

A heat exchanger is probably best removed for cleaning and descaling using an acid based descaler such as Fernox DS1 or DS3

You should not normally have to do anything more to an indirectly cooled engine than you do to your car engine cooling system. A directly cooled engine probably will need periodic descaling. You would need to circulate an acid descaling solution for some time, catching what leaves from the exhaust and returning it to the inlet. Untill the engine reaches full working temperature and the thermostat opens all the flow will simply bypass the engine.

in either case the first thing to check is the overall flow of seawater and if reduced then check the filter then renew the pump impeller.

 

[DavidGrieves]

Hi

I have used Fernox to clean the water ways but it was on a raw water cooled engine, I caught the water out of the exhaust with a bucket and keept recirculating it back into the system. For your fresh water side you could use one of the many cooling system cleaners used for cars. I wouldn't leave Fernox in the engine for long periods(days) engine might not be too happy with it.

 

[orizaba]

be careful what you use as some products have an acid in them that will eat into aluminium,i think these are the ones usually sold as descalers or decalcifiers,check carefully ,as stated before one of the car ones would be best as car engines have a large amount of ally parts in them. the best way to flush the engine is to drain it right down,undo the fitting/pipe at the lowest point and flush through with a hose,or if possible do it the other way and backflush it,the other thing to make sure is that you get no air locks in the system,i usually drill a small hole in the thermostat 1/8 or smallerthis allows air thru when filling but does not stop themostat working properly,also check your impellor,i'd checked ours ,it was all ok no cracks etc,then suddenly reduced water flow ,i checked everything in the system ,filter,water intake,etc was clear and as a last resort i changed the impellor,i could still see nothing wrong with it,but it cured the problem.

 

[chalky]

Hi

Just been through an overheating problem with my Beta 20 hp when pushing the revs over about 2800.
As has been mentioned, make sure the sea water side is completely clean and that the water flow rate at the exhaust is correct (min 20 litres a minute @ 3000 revs) -only a small partial blockage will reduce the flow considerably. If that's ok, check the thermostat in a pan of water on the stove using a cooks thermometer to check that it fully opens promptly at the correct temp - should be about 70-75 degrees C. If that's ok, then it might be the same problem as mine - an airlock in the block water channels somewhere. Try backflushing the engine with clean water from a hose attached to the engine block drain plug and let the water bubble up through the filler hole on the top of the heat exchanger. Drain all the water off and refil the fresh water side and see what happens.

Interestingly, the engine has only been in the boat 3 years and although the fresh water side had been drained and replaced about 18 months ago, there was gunge in the block when I drained it (or tried to drain it as it was blocking the drain tap and needed a good poke about with a small screwdriver to let the water out). The ever helpful guys at Beta didn't seem too surprised and suggested it should be drained and refilled more often than the manual states.

Hope this helps

 

[Kurrawong_Kid]

I seem to remember that there needs to be a particular mixture of water and antifreeze in the block to allow the block to reach a particular temperature. It might be worth checking this, although I would have thought that if you have too much water and not enough antifreeze the engine would run cold or perhaps the anti freeze allows the water to go over 100 C without boiling and if you haven't enough anti freeze the engine will boil.

 

[cliff]

Beta quote a 33%~50% solution however the concentration of ethylene (Glycol) should not
exceed 50%. (tends to knacker hoses etc)
The anti-freeze in the fresh water system enables the boiling point of water to rise to 124°C with a 13 psi pressure cap fitted. The water temperature alarm switch will however be activated at 95° to 100°C. If no anti-freeze or a very weak solution is
used, then the water temperature switch may not be activated before coolant is lost.
IIRC the stat starts to open at ~82°C and should be fully open by 85°C - been a long time since I had a boat with a Beta (Kubota) engine. /forums/images/graemlins/grin.gif
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[stefan_r]

I have used Rydlyme from Ric Industries and found it excellent...also takes scales off props, and any other areas on board.

safe to flush overboard too...apparently.

stef