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Andy_J

Active Member

• Aug 16, 2011

• #1

Whilst trying to identify a misfire on my 4.6. I noticed that the sprak plug on cylinder 3 had been dashed on the top.

This is what I found when I pulled the head off bank 1, I don't think the piston should look like this. The cylinder head has a nice matching look

Do you think I could get away with replacing the piston I am getting the head skimmed as the local engineering place thinks the sealing surface on the head is ok

 

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jamesmartin

Well-Known Member

• Aug 16, 2011

• #2

does it look melted cant tell exactly if does change injector

 

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Andy_J

Active Member

• Aug 16, 2011

• #3

I think it is impact damage, I had a rattle on that bank couldn't work out what the rattle was, but I found a small piece of metal bouncing around the inlet maifold, looked like it my have been in a cylinder bore at one point.

Injector looks fine and the valves are not burn or damaged

 

jamesmartin

Well-Known Member

• Aug 16, 2011

• #4

it wasnt easy to see but if youve found offending item it puts your mind at rest ,i have seen a few with burnt pistons,even though is rare ,doesnt burn valves or rings just ali piston,dont forget to gap rings before fitting,pistons are graded you used to be able to buy that size stamped on block on outer jacket of each bore a single letter

 

jonbill

New Member

• Aug 16, 2011

• #5

do you have a pic of the spark plug? does 'dashed' mean impact damage?
It's hard to imagine a small piece of metal getting into the cylinder, bashing around for a while and then getting out without damaging valves at least.
but then again, it does look nicely shot peened.

 

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Andy_J

Active Member

• Aug 16, 2011

• #6

jonbill said:

do you have a pic of the spark plug? does 'dashed' mean impact damage?

Click to expand...

'dashed' should read 'Bashed'

The 2 electrodes on the plug are touching no gap left