Yanmar 1GM question

[raggy]

Just went to start my Yanmar for the first time and found it had blown out a plug in the front of the main block. I have circled this below. Started on the second turn though which is not bad for 3 years idle.

I knocked to back into the case with a drift and then ran the engine for 30 mins and it seamed fine.

Question is what could cause this and is it the sign of a problem to come?

 

[ghostlymoron]

It could be that your engine has frozen up over the last 3 years and the expansion of water/ice has popped the plug out. There's no great pressure in the water jacket when operating so it should be OK.

 

[testmonkey]

You've blown a freeze out plug and should get a new one.

As seen on other forum: "Freeze out plugs should never be reused. The new ones have a slightly beveled edge that gets bent upon instlation. This is important to make sure it does not blow out when the pressure gets up to specs. if you reuse the old one you are asking for a major emotional event in the engine compartment with scalding water being unpressurized at a rapid rate resulting in MASSIVE amounts of steam... They come in standard sizes at the auto parts store. Cost like $3 "

The motor block has had water in it which has frozen. If you're lucky the freeze out plug saved the engine and no other damage was done. The other option is that you have a crack somewhere in engine block or cylinder head.

 

[NUTMEG]

Ditto above. Core plugs are part of the casting process. If engine running fine I would not worry about it.

Just read last post. No pressure in 1GM10 cooling system, raw water cooled

 

[VicS]

If it leaks you will have to remove it and fit a new one.

If it does not leak then all is well.

 

[Tranona]

Looking at your photo, you have had the usual leak from the anode plate and around the water pump. The latter is critical as leaking sewater here can rust the oil transfer pipe underneath and corrode the front cover. That whole area is a mass of dissimilar metals. Aluminium gear case held onto iron block with mild steel screws, bronze water pump housing mounted through the casing and fastened with steel screws.

Suggest you take it all apart, clean it, replace the screws if corroded and put it back together with Duralac on all the fastenings. A Speedseal is a good idea for the water pump as it makes it easier to remove and seals better than the standard cover and paper gasket. If the oil pipe is corroded, have a flexible one made up by an industrial hose supplier. Also clean all the seawater hoses and the pipe that goes into the block. If the core plug does not leak, leave alone. If it does, replace it.

 

[raggy]

Thanks for the info.

I should point out the pic is from the net as I couldn't get a pic of the one in place.

 

[Tranona]

Hope yours does not show the corrosion in the pic!
.
Still worth checking and cleaning the waterways