Yanmar 1GM10 cheaper parts or original?

[slawosz]

Hi,
I would like to have spare thermostat for my 1gm10 onboard. I wonder if I could trust cheaper ones on ebay - around 25 quid or I should buy original?

 

[Tranona]

Not sure why you would want a thermostat on board as they rarely fail. The big issue with cooling on a 1GM10 apart from the water pump is keeping the small diameter hoses and fittings clear, particularly the T piece that goes into the block. I always bought genuine for mine because although individually parts are expensive you need so few! The only exception perhaps is the exhaust elbow where the aftermarket ones are better than the original.

BTW have you checked yours for perforation of the inner tube as that could be the cause of the steam at higher revs.

 

[slawosz]

Thank you for the answer. What you mean by perforation?
I decided to buy thermostat anyway, as the service manual suggests to do so. At least I will eleminate one element of the puzzle.

 

[Tranona]

The exhaust elbow is twin walled. The inner tube carries the exhaust gases and the water is injected through the outer onto the tube and then flows down to mix with the exhaust and then onwards through system. The weld that joins the two pipes sometimes fails and also the inner tube corrodes (hot seawater!) and water can get sucked back into the engine. One of the symptoms of a leak between the inner and outer is steam in the exhaust because the water is hitting the hot gas too early.

Well known problem with the engine and a service item is to remove the elbow and check that the inner tube is sound and secure. You do that by turning it upside down, blocking up the injection pipe and filling the space between the 2 tubes with water. If it leaks through the inner then it needs replacing. Long term effect is water getting back through the exhaust valve into the engine and causing corrosion usually to the head. V. Expensive!

 

[slawosz]

Thanks. I will check it next time I am on the boat. Will report back here and in other topic.