Thoughts please.

West Cork Paul

West Cork Paul

Man in a Shed
Subscriber
I’m replacing a vertical cylinder head on a Pani 899 as ;

a) the original head has a fractured cooling jacket which was causing coolant to collect and pool in the spark plug channel, and,

b) the head gasket was most likely leaking as evidenced by a load of coolant in the combustion chamber.

(I’m fairly sure that’s the subject of another thread in here).

V head is no off (as is most of the bike off the engine in order to get access).

IMG_2893.webp


IMG_2887.webp


but on close inspection once I’d cleaned the remains of the old head gasket off the barrel mating face there’s some pitting there - arrowed.

IMG_2896.webp


I’ve no idea how it got there 🤷🏻‍♂️ a manufacturing defect 🤔 but the question is, will it affect the integrity of the new head gasket ????
 
West Cork Paul said:
I’m replacing a vertical cylinder head on a Pani 899 as ;

a) the original head has a fractured cooling jacket which was causing coolant to collect and pool in the spark plug channel, and,

b) the head gasket was most likely leaking as evidenced by a load of coolant in the combustion chamber.

(I’m fairly sure that’s the subject of another thread in here).

V head is no off (as is most of the bike off the engine in order to get access).

View attachment 150629

View attachment 150627

but on close inspection once I’d cleaned the remains of the old head gasket off the barrel mating face there’s some pitting there - arrowed.

View attachment 150630

I’ve no idea how it got there 🤷🏻‍♂️ a manufacturing defect 🤔 but the question is, will it affect the integrity of the new head gasket ????
Click to expand...
Maybes aye, maybes naw 😁

Happy to have helped 👍
 
Markduc said:
If that machined gap where the stud comes up doesn’t bother the heat gasket, then I’d be surprised if a couple of small imperfections would
Click to expand...
Agree with Mark, shouldn't affect integrity of the gasket, looks to me like damage from previous maintenance/disassembly than pitting

edit, deffo looks like pitting on the piston crown edge around the valve clearance void
 
West Cork Paul said:
I’m replacing a vertical cylinder head on a Pani 899 as ;

a) the original head has a fractured cooling jacket which was causing coolant to collect and pool in the spark plug channel, and,

b) the head gasket was most likely leaking as evidenced by a load of coolant in the combustion chamber.

(I’m fairly sure that’s the subject of another thread in here).

V head is no off (as is most of the bike off the engine in order to get access).

View attachment 150629

View attachment 150627

but on close inspection once I’d cleaned the remains of the old head gasket off the barrel mating face there’s some pitting there - arrowed.

View attachment 150630

I’ve no idea how it got there 🤷🏻‍♂️ a manufacturing defect 🤔 but the question is, will it affect the integrity of the new head gasket ????
Click to expand...
Can’t see that being a problem Paul as long as it is smooth👍
 
Markduc said:
If that machined gap where the stud comes up doesn’t bother the heat gasket, then I’d be surprised if a couple of small imperfections would
Click to expand...

Good point 👍 except, there’s nowt by the stud to leak across the gasket. Where the pitting/gouge marks are it’s between the combustion chamber and the coolant channels.

BobTheBounder said:
edit, deffo looks like pitting on the piston crown edge around the valve clearance void
Click to expand...

I hadn’t noticed that, going to inspect closer now.

Fight the streets Fmd said:
Can’t see that being a problem Paul as long as it is smooth👍
Click to expand...

It’s not. You can deffo feel it.

The owner’s had the bike since it was 6 months old and he’s not mentioned the head ever having been taken off before in his ownership, can’t see it would have happened in the first 6 months of life as a demo bike but 🤷🏻‍♂️
 
Old head, new head (after I’d cleaned the replacement one). There’s a very small pin missing which sits in an oil path which has now stopped my progress until it arrives. Well it’s described as a pin but it’s not a pin in the sense of a locating pin, it seems it’s there to regulate the flow of oil to the valve train and thus maintain pressure within the lubrication system.

It’s a good job I spotted its absence I guess 👍

IMG_2889.webp
 
West Cork Paul said:
Im asking these questions really as I’m struggling to see an obvious place where coolant was leaking into the combustion chamber.
Click to expand...
Good question Paul, since the head coolant jacket has failed , possibly over time, you may have found yourself a porous head, if the fella had been topping coolant, and the V head has been through many rapid thermal cycles, the old gasket could have pin holed around the o ring part and may have slightly warped that head.
Hard one to pin down cocker.
 
West Cork Paul said:
Im asking these questions really as I’m struggling to see an obvious place where coolant was leaking into the combustion chamber.
Click to expand...
Sometimes with hairline cracks it will be invisible to the eye, only pressure testing will make it clear. Also you are looking at a cold engine, I had a cylinder head cracked on a 6cyl BMW 40 years ago, only under pressure testing it came to light 👍
 
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