Dnepr MT9 - Crankshaft and Connecting Rod Assembly Repair

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Table 4
Maximum Permis sible Values of Wear and Clearances in the Basic Mating Members
of the
Engine
Co mp onent parts um l th ei r co njug ate pairs
Crankpin - connecting rod bushing
Cylind er (face)
Cylind er- piston
Piston pin
Piston pin open ing
P1ston - piston pin
Connect ing rod sma ll end bush
Pi
sto n pin - conncc!ing rod sma ll end bush
Compre
ss ion pis ton ,ring (width)
Piston groov . e- piston ring
Va lve stem
Va lve guide bush in g
Valve ste m - va lve guide bushing
Rocker bushing
Rocker (opening)
Rocker bushing - ro ck er
Tappet
Opening for the tappet
Maximum permiss i bl e dim e nsions.
mrn
dinmeter wear
/ cliametral cl ear-
:t nce
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0. 1 00
0.200
0.250
0.015
0.020
0.0 !0
0.025
0.030
0.050
0.150
(as to hei ght)
0.120
0.150
0.2
50
0.070
0.070
0 .1
20
0.050
0.0
50
2. REPAIRING THE ENGINE UNITS AND COMPONENT PARTS
When repairing th e eng ine unit s and component parts, en sure
that th e clearances a nd int erfe re nces betw ee n the mating parts are
of the m ag nitud es esta blished during factory assembly and specifi ed
in Table 3.
Also, ref er to Table 4, li s ting the ma x imum p erm i ss ible va lu es of
wear a nd cleara n ces in the basic mating me mb ers oi th e engine.
Repairing the Crank and Connecting - rod Assembly
The cr ank and connecl ing-rod asse mb ly is li ab le lo r epai rs in
case the following fau lts are detecte d in the en gine:
k no cks in th e zone of cra nk sh aft bearings, co nn ect in g rod big
<m el sm all e nd s, cy lind er-a nd-pi sto n asse mbl y;
co
mpre ssi on drop in th e cy lind e rs due to poor a ir -tig htn ess of
the cy lind er rings, resulting in th e pow er drop a\ld incr eased oil con -·
s umption ;
in
th e case of total disa sse mbly of the engine, if some of the
parts of th e crank a nd connecting -rod assemb ly ar e fou nd to be de-
fe ctive.
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