Coolants - Mercedes-Benz 300 SD 1978 Owner's Manual

Coolants

The coolant Is a m ixture of w ater and
antifreeze. In production, the cooling
system is filled with an antifreeze-
water m ixture offering protection to
approx. -2 2 ° F (-30° C). The red mark
on the tem perature gauge in the
instrum ent cluster is m atched to this
antifreeze-w ater m ixture (approx.
boiling point 257° F/125°C ). The p ro ­
tection against corrosion is also en­
sured by this m ixture m aking it un­
necessary to add a corrosion in h ib i­
tor.
The coolant rem ains in the cooling
system all year round and m ust be
renewed after 2 years at the latest.
This applies also to tra ile r operation,
hard driving and to vehicles driven in
tropical countries.
If coolant has leaked from the cooling
system, replace the m issing quantity
with water and a recom m ended brand
of antifreeze. For norm al re p le n ish ­
ment (due to evaporation of water)
plain water will do.
The w ater should be clean, soft to
m edium soft and contain the m in i­
m um am ount of scale form ing
m inerals (potable w ater quality).
The coolant m ixture should always
contain enough antifreeze to ensure
protection to a m inim um of -4 ° F
(-20° C).
If antifreeze is not available, add a
corrosion in h ib ito r to the cooling
w ater to ensure p ro p e r protection
against corrosion. To treat the c o o l­
ing water, do not use m ore than 1 %
(10 cc c m /l) of a recom m ended
corrosion inhibitor.
W ithout antifreeze in the cooling
system, the w ater already starts b o il­
ing at approx. 224° F (118° C), w hich
means that the poin te r of the te m p e r­
ature gauge in the in strum en t cluster
may still be below the red mark.
Antifreeze
P rior to the onset of the cold season,
check the co o la nt fo r its resistance to
Fuels Coolants Lubricants etc.
cold. Repeat this check during the
cold spell. Regular testing of the
antifreeze concentration is carried out
only at each MERCEDES-BENZ
m aintenance service.
To prevent dam age to the cooling
system, fill only with recom m ended
brands of antifreeze.
Any MERCEDES-BENZ service
station will readily advise you on
recom m ended antifreeze brands.
P rotection
up to A ntifreeze
- 4° F
4.5/3.7 U S /Im p. qts.
(-2 0 ° C)
(4.25 I)
-2 2 ° F
5.8/4.8 U S /Im p. qts.
(-3 0 ° C) (5.50 I)
-4 0 ° F 6.6/5.5 U S /Im p. qts.
(-40 ° C) (6.25 I)