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9LD Workshop Manual _ cod. 1.5302.286 - 3° ed_rev. 02
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Disassembly / Reassembly
Valves
Components:
1 Intake valve
2 Spring seat
3 Valve stem seal ring
4 Spring
5 Retainer
6 Half collets
To r em ov e ha lf co ll et s fi r ml y pr es s d ow n as s ho wn in the f ig ur e.
Valve stem sealing rings - Reassembly
Lubricate the inside of the sealing ring with Molikote BR2 Plus and
insert them all the way onto the guides using tool 1460-108.
To prevent deformation of the sealing ring 1 as it is inserted onto
the valve guide 2 insert it onto tool 3.
Lubricate valve stem with the same type of grease; insert the valves
into the guides rotating them particularly as they enter the sealing
ring.
Valve springs
Measure free length with a gauge.
Using a dynamometer check that the spring length under two dìfferent
loads corresponds to the values below:
Free length A = 52 mm
Length B compressed by a 210.6 N = 35.8 mm
Length C compressed by a 340.6 N = 25.8 mm
Replace spring if length is 1 mm or more below the stated values.
Valve material
Intake valves A
Material: X 45 Cr Si 9-3 UNI En 10090
1 Chromium-plated portion
a 45.5° ÷ 45.75°
Exhaust valve B
Shaft and head are made of 2 different materials.
2 Welded portion
3 Chromium-plated portion
4 Portion made of X 45 Cr Si 9 - 3 UNI EN 10090
5 Portion made of X 55 Cr Mn Ni N 20 - 8 UNI EN 10090
a 45.5° ÷ 45.75°
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