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| Type
& amount of coolant used |
|
Use phosphate-free coolant/anti-freeze that is mixed with distilled water (see
mixture table below). VW's Autobahn brand (part #ZVW 237 105) is
recommended, but not required. You should never mix coolant/anti-freeze brands or types, even
to top off the expansion tank or radiator; always flush the system before
switching brands or types (ex: blue stuff to red stuff) -- corrosion and
leaks will result if brands or types are mixed.
| Mixture Percentage |
Amount of Coolant |
Amount of
Distilled Water |
| 50/50 -- min |
2.3L |
2.3L |
| 60/40 |
2.76L |
1.84L |
| 70/30 -- max |
3.22L |
1.38L |
|
the above is based on the 4.6L needed to fill the
system (with an expansion tank) |
| Mixture Percentage |
Amount of Coolant |
Amount of
Distilled Water |
| 50/50 -- min. |
2L |
2L |
| 60/40 |
2.4L |
1.6L |
| 70/30 -- max. |
2.8L |
1.2L |
|
the above is based on a 4L container of coolant |
Not keeping up with timely
coolant flushes can lead to internal cooling system corrosion.
Flush the coolant every 30,000 miles or every 2 years, whichever comes
first.
|
| Coolant expansion
tank |
| From 1979-1982, Rabbit
Convertibles did not have a coolant expansion tank; they had the old style
system wherein the coolant was
added directly to the radiator via the radiator cap. From 1983 to 1993,
Rabbit Convertibles and Cabriolets came with expansion tanks; some 1982
models may have the bracket for the expansion tank but VW continued to use
the old cooling system on most, if not all, 1982s.
If you would like add an expansion tank to your
system you will need the following parts: newer style radiator, hose from
radiator to expansion tank, expansion tank, hose from expansion tank to
coolant return pipe and a coolant return pipe. |
| My
Cabriolet doesn't start when hot, but does start
after it sits for 15+ minutes |
| Is it an automatic? Automatic
Cabriolets are notorious for this problem due to the poorly-located starter
(next to the exhaust manifold). The best solution for this problem is to
install a starter relay: click here
for a how-to. |
| The
radiator cooling fan |
|
Radiator cooling fan won't turn on:
Check the fan thermo switch:
Disconnect the thermo switch connector; using a jumper wire, make a
connection between terminals (2-speed fans: low speed is red/white wire,
high-speed is red/black). If the fan runs, the thermo switch is faulty
and needs to be replaced. If the fan fails to operate, check for
voltage at the thermo switch connector (red wire). If voltage is not
reaching the connector, check fuse #1. If the thermo switch is good and
the fuse is good, the thermostat (in the water pump housing) may be faulty.
Radiator cooling fan won't shut off: Replace the radiator fan
switch and/or the radiator fan relay.
(Cabriolets equipped with after-run systems (1988+) may have the cooling fan
run up to 15 minutes after the engine is turned off.)
Coolant boils out of the reservoir (coolant
temp is normal, fan turns on, no leaks detected):
Faulty reservoir cap, faulty reservoir, faulty
after-run thermo switch and/or relay (1988+), blocked radiator, faulty
cooling fan thermo switch.
 The radiator cooling fan
operates under the following conditions:
-
When the coolant reaches a specified temperature.
-
The thermo switch in the radiator is normally open; when the coolant
reaches the switch's pre-determined temperature (see below), it closes
completing the path to ground, which turns the fan on.
-
1988-1993: The two-speed fan runs on low.
-
When the A/C compressor engages.
-
When any of the A/C settings are switched on and the compressor engages,
an electrical signal is sent to the A/C relay, which in turn sends a
signal to the fan, switching the radiator cooling fan on.
-
1988-1993: The two-speed fan runs on high.
-
After engine shut-off, if the under-hood temperature is above a specified
temperature.
-
1980-1987: The single-speed fan will run until the radiator fan thermo
switch opens, thereby interrupting the ground path. The fan
usually doesn't run for more than a couple of minutes and definitely not
more than 5 minutes. If the fan runs longer than 5 minutes, there
is a problem.
-
1988-1993: The two-speed fan will run on high until the after-run thermo
switch cuts its electrical path to the after-run control unit. The
fan usually doesn't run for more than 5 minutes, but is capable of
running for up to 15 minutes. If it runs longer than 15 minutes,
there is a problem.
Cabriolets up to 1987 with A/C do not have two-speed
cooling fans; these cars have one-speed fans that are two-stage (fan
is turned on when the A/C is turned on). From 1988-1993, Cabriolets
were equipped with two-speed fans; those with A/C would then have
two-speed, two-stage cooling fans.
|
Switch* |
Temperature ratings |
Turns fan on at |
Turns fan off at |
Proper thermostat* |
|
Radiator thermo switch, one-speed |
95-84 |
95°C (203°F) |
84°C (183°F) |
87°C |
|
Radiator thermo switch, two-speed |
95-84/102-91 |
95°C (203°F) / 102°C (215°F) |
84°C (183°F) / 91°C (196°F) |
87°C |
|
Radiator thermo switch, two-speed |
85-80/93-88 |
85°C (185°F)/ 93°C (199°F) |
80°C (176°F) / 88°C (190°F) |
80°C |
|
After-run thermo switch (CIS) |
110 |
110°C (230°F) |
70°C (158°F) |
- |
|
After-run thermo switch (Digi) |
100 |
100°C (212°F) |
70°C (158°F) |
- |
|
*Notes:
1) An 87° thermostat begins opening when the coolant temperature has
reached 87°C and is fully open at 102°C.
2) If wanting to change to a lower-temp thermostat, you must swap out
the thermo switch with a matching temperature thermo switch (or vice
versa). The low-temp thermostat is 80°C; the matching thermo
switch is 85-80°C.
3) Some parts stores, such as German Auto Parts, incorrectly list the
thermo switches as being "with A/C" and "without A/C". From 1980
through 1987, Cabriolets used one-speed fans and use the black 95-84°
switch; 1988-1993 Cabriolets use two-speed fans and use the white
95-84/102-91° switch; A/C is irrelevant. See the
electrical page for further info. |
|
| The coolant temp warning light
is flashing |
| Coolant level is low; coolant
is leaking; coolant is getting too hot. Possible causes: burst hose;
cracked hose; loose hose clamp(s); clogged/restricted hose(s); faulty
thermostat; faulty coolant reservoir (or radiator) cap; clogged/leaking
radiator; faulty coolant/water pump; air in the cooling system; incorrect ignition and/or valve timing;
electric cooling fan not switching on. If all of the preceding are found to
be okay, the temperature gauge sending unit and/or
level sensor ('90+) and/or the gauge itself could be
faulty. |
| Radiator cards
(baffles) |
| The purpose of the cards is to
direct airflow through the radiator with little air escaping
around the radiator; this enables the cooling system to work more
efficiently. New ones are no longer available. The cards were originally
made out of cardboard which, over time, disintegrates. Rather than
sourcing used cardboard radiator baffles, you can easily make new,
long-lasting ones yourself out of sheet metal from your local home
improvement center.
Simply click on the icons in the table below to download the templates (only
the AutoCAD download contains genuine, full-size templates that can be
printed at your local Kinko's, etc.; the others contain measurement
templates for use as guides in making the baffles).
|
| Oil coolers |
| Only Cabriolets with JH
engines in North America have oil coolers; "why?" remains to be answered. In Europe, only the
EG, JH, 2H, DX and KT engines
came with oil coolers.
If your Cabriolet is without an oil cooler, you
can install the OEM cooler (additional coolant hoses will be needed), or an
aftermarket cooler that utilizes air, rather than coolant, to dissipate heat
from the oil. |
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