Piston clearances

[Straiton70]

Hi,

I've stripped down my 2.0 Zetec Silvertop engine as it failed leak check past the piston rings. What I found was the piston ring gaps were over double the spec.

For the rebuild.

Measuring the cylinder bores with right tools, my bores are 84.850mm vs 84.800mm spec and pistons 84.73mm vs 84.770mm spec on average across all cylinders. The minimum piston to cylinder gap is 0.03mm and I have an average of 0.12mm. I cannot find a maximum gap.

Is the gap okay or should I get a re-bore with bigger pistons?

[Graham]

if those are standard, ie not forged pistons, thats a huge clearance. you will have piston slap and poor control of the rings. but thats no suprise because you have already meassured your bores as being almost 2 thou too big

[Straiton70]

Hi,

Thanks for confirming my thoughts. They are standard pistons.