Piston rings, replace

# Replacing piston rings

Remove pistons

Remove old rings from the pistons

Clean piston ring grooves of all carbon build up.

Check the side clearance of new piston rings:

##### Top ring :

##### 0.06-0.09mm (0.0024-0.0035")

##### Middle ring, tapered edge facing up:

##### 0.06-0.09mm (0.0024-0.0035")

##### Third (oil) ring :

##### 0.02-0.05mm (0.0008-0.0020")

Install piston rings into bore one at a time.
Measure end gap of rings:

##### Top ring :

##### 0.30-0.55mm (0.012-0.022")

##### Middle ring, tapered edge facing up.

##### 0.30-0.55mm (0.012-0.022")

##### Third (oil) ring

##### 0.25-0.50mm (0.010-0.020")

Install rings so the word "top" faces up

Plain compression ring goes on top

Tapered face ring goes in middle

Oil control ring goes on bottom.

E30 M3 Repair Manual V2.7. Copyright ©1999-2001 Koala Motorsport & Brett Anderson