Lotus 2004 Eleven Service Notes page 131

Lotus Service Notes
Overhaul Notes
1. Timing Marks (2ZZ only)
Take care when setting the engine to its 'timing' postion. Crankshaft at TDC, inlet cam pulley mark facing
inwards on centreline, exhaust cam pulley mark facing inwards but ONE TOOTH COUNTERCLOCKWISE
from centreline.
2. Valve Clearances
a) It is unlikely that valve clearances will require adjustment unless components are replaced. A single
forked rocker arm is used to operate a pair of valves, which are shimmed during manufacture for equal
clearance. Routine service clearance checks should be made between the cam and roller follower. Only
if a valve or rocker arm is replaced need the clearance between individual valves and the rocker arm be
measured. Adjustment procedure is detailed in the text.
b) When using the shim adjustment special tool, before removing a shim from a valve stem, ensure that
the oil drain passages on the exhaust side of the head are blocked with paper towel. Shims are easily
dropped and may fall down the drain passages into an oil gallery in the crankcase, requiring engine removal
to retrieve.
3. Stretch Bolts
The cylinder head bolts, big end bolts and main bearing cap bolts are 'stretch' type with an angular tight-
ening procedure. The bolts should be measured to determine their suitability for re-use. Measure length
or diameter as specified in the text. Note that the big end bolts are 8.7 to 8.8 mm standard diameter, with
8.5 mm minimum.
4. Timing Chain Tensioner
The maintenance free timing chain tensioner uses spring tension and engine oil pressure in conjunction
with a non-return ratchet mechanism to maintain chain tension. A pivotted hook on the tensioner body is
provided to aid assembly, by enaging with a pin on the spring plunger to hold the assembly retracted whilst
fitting. After fitment to the timing cover, the engine is then turned backwards so that the chain forces the
plunger into the tensioner body, which action pushes the hook into a disengaged position and allowing
tension to be applied on resumption of normal rotation. The ratchet mechanism prevents subsequent
plunger retraction.
5. Bearing Shell Size Coding
Note that the main bearing shells and big end shells are selective thickness dependent on journal and
housing size. Pistons are one size only. No reboring or crankshaft grinding is permitted.
Main bearing housing size codes are stamped onto the cylinder block, and crankshaft journal size codes
on the crank. If necessary, Plastigage can be used to deterime oil clearance. Big end codes are stamped
only on the connecting rod caps. Service replacement shells will also be marked on the back with the size
code.
6. Knock Sensor (2ZZ only)
The knock sensor used for Lotus applications is an annular type fitted over an M8 stud, with the retaining
nut tightened to 20 Nm. Note that the 1ZZ engine does not use a knock sensor.
7. VVT Unit Refitment
The variable valve timing unit mounted on the front of the inlet camshaft, is secured in the fully retarded
position when the engine is stopped, by a spring loaded pin. When fitting the unit to the camshaft and
tightening the retaining bolt, it is essential that no torque is applied to the sprocket, or damage could be
caused to the locking pin. Ensure that the dowel pin in the camshaft front flange is correctly located in
the corresponding slot in the VVT hub before inserting the retaining bolt. Hold the camshaft only with a
spanner on the flats provided, and tighten the retaining bolt to 54 Nm.
Section EH
Page 8