Cooling System Inner Circuit; Coolant System Outer Circuit; Water Pump - Volvo 164, 1970 Service Manual

Fig. 2-91. Water pump
1. Ho usin g
2. Imp e ll er
3. Sea l rin g
4. Fla nge
5. Lock sp rin g
6. Shaft w ith ba ll bearings
(int egra l uni t)
7. W ear r in g
2
mereases (see Fig.
2-96).
W,ith th is arran gement, the
fan speJ ed sho ul d never exce, e d about
3000-3500
r.p.m.
The fa n no ise outp ut w ould t hen be ,Io w compared
wirth a fan whi ch ru·ns a t th e sam e hig h speeds as th e
water pump. Comp are d with this lartf' e r type of fa n,
the output loss wHI be less fo r the s li p-cou p lin g type
fan .
O n vehicl e s for U, S.A. a fi xed fa n is fitted with blades
which straighten out ot higher sp eeds. Thi s fan nas
a particular,ly good cooling effekt at low speeds.
A centrifugal pump, Fig.
2-91,
takes care ' of the
coolant
~iJrctJ. lation
and a twin operating thermostat
provides rapid waming up of the eng·ine and con-
tributes to the engine maintaining the most suitable
t' e mperature under al,1 operating conditions.
In order to achieve the desired effect with the sea le d
cooling system, it must be wel,1 fined and not leak.
As coolant, a mixture consisting of
50
%
ethyl,ene
glycol and
50
%
water is used all yeaJ r round. This
mixture provides protection against frost down to
minus
35°
C (minus
32°
F) and should be changed
every other year, on which occasion the engine, radia-
tor and expansion tank shou,l,d be flushed with clean
water.
If Volvo anti-frost for cars is used (it is red in colour),
it should not be mixed with othe'r types of -anti-frost.
COOLl NG SYSTEM INNER CIRCUIT
(BY-PASS)
The aooling system consists of two circuits, an inner
and an outer one. When ,the engine is warming up
and in very cold weather when large quantities of
Fig. 2-92. Coo la nt fl ow, the rmostat closed
1. To radiator
5. Distributing pipe
2. Thermostat 6. Wate r pump
3. Cylind e r head
7. From radiator
4. By-pass pipe
hent are required for warming up the in s ide of the
ca'r, the coolanrt circula· t es almost e xclusive·ly throug h
th' e inner circuit (the by-pass). This circuit covers the
engine and ear heater. The thermostat is closed, that
is, the outlet to the radiator is shut off. The coolant
passes through the thermostat
by ~pass
to the distribut-
ing pipe
(5,
Fig.
2-92)
in the cylinder head. This resul,ts
in a uniform cool,ing of the warmeSlt parts in the
cylinderhead. Even the parts around the spa,rking
plugs are also cold and thereby maintained at a
con'Sfant temperature. The coolant surrounding the cy-
linder wa,IIs is circulated by means of thermo-syphon
action.
COOLANT SYSTEM OUTER CIRCUIT
When the coolant in the inner circuit reaches a suit-
abel temperature for the engine, the thermostat be-
gins to open during which t ime the by-pass between
the thermostat housing and the pump is graduaHy
closed, see Fig.
2-93.
2 : 41