Noisy Connecting Rods - Fiat 850 Sedan 1968 Shop Manual

Cran kshaft Knocks
(con!jnu~).
ENGINE: TROUBLES AND CORRECTIONS
19
POSSIBLE CAUSES
3) Out-of-round or tapered main bearing journals.
4) Crankshaft out of balance.
5) Poor oil delivery.
6) Low oil pressure.
7) Loose flywheel on crankshaft.
8) Improper or diluted oil.
Noisy Connecting Rods.
REMEDIES
3) Remove crankshaft, check journal diameter: next grind
crankshaft and replace bearings as outlined under (( Crank-
shaft
)l.
4) Remove crankshaft and check balance with flywheel and
clutch installed as outline:l under «Crankshaft».
5) Check and rebuild oil pump as outlined in relevant chapter.
See that the 011 lines are not plugged or restricted.
6) Take down and disassemble engine, then:
a) Check the 011 pressure relief valve for binding and proceed
as required.
b) Check the seal rings in crankshaft rear bearing oil shield
disk for wear and replace them, if worn.
7) Tighten flywheel screws with specified torque.
8) Replace oil by correct grade as tabulated on page 7.
COlUlecting rod noises are usually more intense than main bearing knocks. The noise is more evident,
as a rule, with the engine idling and in neutral and becomes louder when engine speed is increas ed.
Connecting rod noise can be best located by short circuiting one spark plug at a time.
POSSIBLE CAUSES
1) Excessive clearance between con rod bearings
and Journals.
REMEDIES
1) Take down rod
and journals.
crankshaft.
bearings and check wear of rod bearings
If
necessary, replace bearings and grind
2) Out-of-round or tapered connecting rod journals.
3) Poor oil delivery.
4) Low 011 pressure.
5) Misaligned connecting rods.
6) Improper or diluted 011.
2) Remove crankshaft, grind connecting rod journals and
replace bearings.
3) Check and rebuild 011 pump as outlined in relevant chapter.
See that 011 lines are not plugged or restricted.
4) Take down and disassemble engine, then:
a) Check the 011 pressure relief valve for binding and pro-
ceed as required.
b) Check the seal rings in crankshaft rear bearing 011 shield
disk for wear and replace them, If worn.
5) Dismantle connecting rod~piston assemblies and align con-
necting rods as outlined In covering chapter.
6) Replace 011
by
correct grade as tabulated on page 7.