287 HO 03 M272 (FAH) 08-05-04 - Bill's Den: Home

M2

287 HO M272 (FAH) 10/05/04

272 Engine

1

Objec

Students will be able to:
• identify differences between M112 a
• explain the camshaft adjusters oper
• identify major components of the M
• explain function of the swirl flaps
• explain function of the temperature

ctives

and M272
ration
M272

management system

2

Cont

Comparison
Highlights
Motor mechanicals
Oil level switch
Crankcase ventilation
Cylinder head
Intake manifold
ME 9.7
Crank sensor
O2 sensors
Three way catalytic converte
Ignition coil
Mass airflow
Temperature management
Fuel tank
Speed sensitive power steer

tents 4
6
ers 9
ring 12
16
18
29
40
46
49
50
52
54
55
59
64

3

M272 – M112

M272 M1
3.5 litre 3.2

268 hp @ 6000 rpm 214

258 lb-ft @ 2500 to 5000 rpm 228

Compression Ratio 10.7 : 1 Co

Sparkplugs per cylinder 1 Sp

ME 9.7 ME

Coil On Plug Do

2 Comparison

112
2 litre

4 hp @ 5700 rpm
8 lb-ft @ 5700 rpm
ompression Ratio 10.0 : 1
parkplugs per cylinder 2
E 2.8
ouble ignition coils

4

Comp

Red line (Dash) = power kW 200 180 kW
M112 3 valve 180 350 Nm
160
Blue line (solid ) = 140 2000 3000
M272 4 valve 120
100

80
60
40
20

0
1000

parison

190 kW 400 Torque Nm
M112
6000 380 5
4000 5000
360

340

320

M272

300

280

260

240

220

200

7000 RPM

New M272 introduce
Lets look at s

ed in the new SLK 171
some highlights

6

M272 Hig

• M112 replacement

• 3.5 litre displacement

• Counter rotating balance shaft

• Stiffer engine with lateral main
bearing attachments

• 4 valve continuously variable
camshafts intake and exhaust
(DOHC)

ghLights

7

M272 Hi

ighLights

• 90 degree V-6

• Two stage Intake manifold

• Turbulence flaps in the
intake ports

• ME 9.7 control unit
mounted on top of engine

• Electrically assisted
thermostat

• No EGR valve
– Both cams adjust

8

Lets take a look at what

t changed mechanically

9

Motor Me

• Based off of M112 engine
• Bore and Stroke increase

compared to M112
• Die cast aluminum crankcase
• Silitec coated cylinder liners
• Starter openings both sides of block
• 8 lateral main bearing bolts

echanicals

k

10

Crank

• Crankshaft lighter as compared to M1
• Wider main bearings as compared to

used to reduce vibration
• Iron coated cast aluminum pistons

kshaft

112
M112

11

Balance shaft, fa
Oil sensor, n

amiliar function
now a switch

12

Balance

• Balance shaft similar to the M112
• Balance shaft rotates opposite

crankshaft

e Shaft

13

Oil Leve

• Reed contact oil level switch S43 repla
B40

• Only one pin of the two pin connector
• S43 mounted in oil pan
• Chain driven oil pump
• Vehicle equipped with an oil level dips

el Switch

aces
used

stick

14

Partial and full load crank

kcase ventilation system

15

Crankcase

Ventilation

16

Cylinder
4 val
DOH

Cam ad

r head
lves
HC
djusters

17

Cylinde

• New design cast aluminum cylinder he

• 4 overhead camshafts (DOHC)

• 4 valves per cylinder, improve torque
and horsepower compared to 3 valve
engines

• Camshaft upper bearing surfaces
integrated into cam housing cover

• Nickel coated high strength
steel exhaust valves

er Head

eads

18

Cylinde

• 4 Cam adjusters
• 4 Cam Sensors
• ME can detect Cam position

with ignition on
• Intake cam is chain driven and

drives exhaust cam via gear

er Head

19

Chain Te

• Step type chain tensioner with intern
• Located at the lower right front engin
• Must be manually reset if removed
• Failure to preset tensioner before

assembly will result in engine dam

ensioner

nal spring
ne

e
mage

20

Camshaft Tim

• Vane type, oil pressure controlled
adjusters

• Continuously variable

• 40° advanced for intake (from 4°
BTDC to up to 36° ATDC)

• 40° retard for exhaust (from 30°
BTDC to up to 10° ATDC)

ming Adjusters

21

Exhaust C

Note: Retaining nut at front timing

Cam Gear

g adjuster is reverse thread

22

Camshaft Pos

• 4 Hall effect sensors, one for
each camshaft

• True Power On (TPO) sensor
technology capable of detecting
cam position with stationary
engine

• Right and left camshaft signals
staggered by 240° camshaft
angle

• Signal is low in absence of a
window

sition Sensors

23

Impulse

• Four impulse wheels used on the
M272 mounted on the front of each
camshaft timing adjuster
– Each impulse wheel has a differ
part number

• The openings of the impulse wheels
help ME determine the camshafts
exact position

• Can only be used one time!

• If new impulse wheels are not us
the pins could shear off causing
massive damage to adjusters

Wheels

rent
s

sed Gouging of
mounting surface
Both locating pins sheared
off when reinstalled

24

Exhaust C

• Exhaust Cam 2 piece gear

• Smaller outer gear spring
loaded for noise reduction

• Gear must be held in place
prior to disassembly

• Segment Ring must be
replaced once removed

• Adjuster bolt reverse
threaded

Cam Gear

25