SEAT Workshop Service and Repair Manuals

Piston and conrod - assembly overview

1 -	Conrod bolt

q	On vehicles with 1.8 ltr. engine: 30 Nm + turn 90° further

q	On vehicles with 2.0 ltr. engine: 45 Nm + turn 90° further

q

Replace

q	Oil threads and contact surface.

q	Use old bolts when measuring radial clearance

q	When measuring radial clearance, tighten to 30 Nm but do not turn further

2 -	Bearing cap

q	Note fitting position:

q	Due to the cracking method used to separate the bearing cap from the conrod in manufacture, the caps only fit in one position and only on the appropriate conrod

q	Mark cylinder allocation -A-

q	Installation position: Marking -B- faces towards pulley end.

q	Separate the new piston rod → Chapter

3 -	Bearing shells

q	Installation position → Fig.

q	Do not interchange used bearing shells (mark).

q	New axial play: 0.10... 00.35 mm Wear limit: 0.40 mm

q	Checking radial clearance with Plastigage: new: 0.02..0.06 mm Wear limit: 0.09 mm. Do not turn crankshaft when measuring radial clearance.

4 -	Pressure release valve

q

27 Nm

5 -	Oil spray jet

q	For piston cooling

6 -

Circlip

7 -	Piston pin

q	If difficult to move, heat piston to approx. 60 °C

8 -

Piston

q	Checking → Fig.

q	Mark installation position and cylinder number.

q	Arrow on piston crown points to pulley end

q	Install using piston ring clamp

q	Piston and cylinder dimensions → Chapter

q	Checking cylinder bore → Fig.

9 -	Compression rings

q	Offset gaps by 120 °

q	Use piston ring pliers to remove and install

q	„TOP“ or „R“ must face towards piston crown

q	Checking ring gap → Fig.

q	Checking ring-to-groove clearance → Fig.

10 -	Oil scraping ring

q

2-part

q	Offset gap of top steel element of piston ring by 120° to next compression ring.

q	„TOP“ or „R“ must face towards piston crown

q	Offset gaps of individual parts of oil scraper ring.

q	Checking ring gap → Fig.

q	Ring-to-groove clearance cannot be checked.

11 -

Conrod

q	Only a complete set may be replaced

q	Mark cylinder allocation -A-

q	Installation position: Marking -B- faces towards pulley end.

q	Separate the new piston rod → Chapter

Checking piston ring gap –  Insert ring at right angle to cylinder wall from above and push down into lower cylinder opening approx. 15 mm from bottom of cylinder. Use a piston without rings to push ring into bore.

Piston ring Dimensions in mm	When new	Wear limit
compression ring	0,20...0,40	0,80
Oil scraping ring	0,25...0,50	0,80

Checking ring-to-groove clearance –  Clean groove in piston before checking clearance.

Piston ring Dimensions in mm	When new	Wear limit
1. compression ring	0,06 … 0,09	0,20
2. compression ring	0,03 … 0,06	0,15
Oil scraper rings	cannot be measured

Checking pistons –  Measure approx. 10 mm from the bottom edge, perpendicular to the piston pin axis. t  Difference between actual and nominal diameter: not more than 0.04 mm.

Check bore Special tools and workshop equipment required t  Interior bore 50 ... 100 mm.   Caution Machining (reboring, honing, grinding) cylinder bore with workshop equipment is not permitted. The surface of the cylinder bore is damaged by machining. –  Take measurements at 3 positions in both lateral direction -A- and longitudinal direction -B-. t  Difference between actual and nominal diameter: not more than 0.08 mm.   Note Measuring the cylinder bores must not be done when the cylinder block is mounted to the engine and gearbox stand -VAS 6095-, as incorrect measurements may result.

Assembly position of the bearing shell –  Position bearing shells in centre of conrod and conrod bearing cap when fitting. Dimension -a- must be identical on both sides.