Yanmar waterways blocked - by headgasket.

[NPMR]

Having got the head back for my Yanmar 1GM10, from being refurbished, skimmed and valves ground in etc., I was going to put it back but when I took the remains of the old head gasket off, several of the waterways in the main engine block, seemed to be 'blocked', with salt or similar.

However, when I look at the new gasket, these same waterways (if that's what they are), are actually 'blocked' or closed by the gasket. The salt etc is just what is up against where the gasket sits over the 'hole'.

Can anyone explain this? Why would there seem to be waterways but actually then not seem to be used?

The new gasket and the old are identical and the new one is a Yanmar original, so would appear to be the right one, from a Yanmar dealer!

Most intriguing.

 

[cliff]

Can anyone explain this? Why would there seem to be waterways but actually then not seem to be used?.

They are not waterways, rather they are holes left over from the casting process - used to support the sand cores - and hence are blocked off by the gasket - have a look at the block and you will find no corresponding holes into the block waterjacket.

 

[NPMR]

They are not waterways, rather they are holes left over from the casting process - used to support the sand cores - and hence are blocked off by the gasket - have a look at the block and you will find no corresponding holes into the block waterjacket.

Makes sense. I'll have a proper look down the holes with a torch when I go back (again!) to fit the head. This time, WITH the gasket goo!

How many times does someone who forgets stuff easily have to go backwards and forwards from home to boat to finally get it together AND FINISH A JOB!!!?

(Actually I put all the stuff together in two bags so as NOT to forget but managed to take only one bag!!)

 

[ffiill]

You will see same on any cylinder head-first time I had a car engine apart many years ago i hant a clue what the holes were for.

 

[Niander]

The head gasket needs to go the right way up
and it is possible to get it wrong!