COMPRESSION TEST
The results of a compression check can be used to determine if an engine is in good operating
condition or if reconditioning is needed.
Low readings can indicate several conditions or a combina-
tion of different conditions:
POSSIBLE CAUSE
I
REMEDY
A.
Cylinder head gasket blown.
I
A.
Remove head, replace gasket, reinstall
head, recheck compression.
8. Cylinder head warped or loose. B.
Remove head, check for flatness (see
cylinder head service), reinstall and
secure in proper sequehce to specified
torque value.
c.
Piston rings worn-blowby occurring.
I
c.
Recondition exzgine. ’
D. Valves leaking or too tight tappet
clearance.
I
D.
Recondition valves and seats and adjust
tappets.
Higher than normal compression can indicate that excessive carbon deposits have built up in the
combustion chamber. Be sure air cleaner is clean and exhaust is not restricted before checking corn-
,
pression.
Insert gauge in spark plug hole and take several readings on each cylinder.
Consistant
readings in the 110 to 120 psi range indicate’ gdod compression.
Reconditioning is indicated if readings
fall below 100 psi or if readings between any cylinders are far apart.
TIGHTEN
HEAD WITH TORQUE WRENCH - 35 FT. LBS.
.
.
4
0
1
0
7
0
~~ _~
FIGURE 8-2
-- CYLINDER HEAD BOLT TIGHTENINGSEQUENCE
.
.
82 0
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