Subject: VW Type 4 engine, oil-pressure sender installation adapter
Nigel
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posted on March 29th, 2006 at 11:17 PM
VW Type 4 engine, oil-pressure sender installation adapter
VW TYPE 4 ENGINE, OIL-PRESSURE GAUGE SENDER, INSTALLATION ADAPTER
Written & Compiled by Nigel A. Skeet
It is well recognised, that an oil-pressure gauge, is an invaluable supplementary instrument for air-cooled VW
engines. Unfortunately, the fitment of an oil-pressure gauge sender unit, to the VW Type 4 engine (as used in
the VW 411 & 412, VW-Porsche 914-4 and 1972~83 VW 17/18/2000 Type 2), is not as straightforward as the
other engines, owing to the position of the M10 x 1•0 mm, crankcase oil-pressure tapping and its proximity to
the ignition distributor. In addition, any connection to the oil-pressure tapping, must pass through the access
hole in the large sheet-steel coverplate, which shrouds the upper portions of cylinders 3 & 4.
It is possible to screw an oil-pressure gauge sender, directly into crankcase oil-pressure tapping, but first it
would be necessary to enlarge the access hole in the coverplate, to a diameter of at least 43 mm (i.e. 1–11 /16
inches). However, to avoid leakage of engine cooling air, it is necessary to seal the gap around the periphery of
the gauge-sender, but this is extremely difficult, owing to the shape of the coverplate. In order to gain access
for an open-ended spanner, to tighten or loosen the oil-pressure gauge sender, whenever it is fitted or removed,
it is necessary to first remove the left-hand inlet manifold and coverplate. Using a tommy-bar between the
gauge-sender's electrical terminals, to tighten it in position, is liable to cause damage, so is not recommended.
Some years ago, when I was investigating the transplantation of a VW Type 4 engine, into my family's 1973
VW 1600 Type 2, I devised a neat installation adapter kit, for our existing oil-pressure gauge-sender and an oil-
pressure switch, which avoided the need to modify the coverplate or remove anything other than the standard
oil-pressure switch. This comprised a home-made, 50 mm (i.e. about 2 inches) tall spacer mast and various 1-
way banjo fittings; the components of which were readily available, either new or second-hand. I did examine
several other methods of installation, but in my opinion, this was the neatest and least obtrusive.
Although a generally uncommon thread size, M10 x 1•0 mm is used for metric oil-pressure tappings, hydraulic
brake fittings, some spark plugs, certain domestic lamp fitting adapters, and the valve rocker adjustment screws
of the 1975~83 VW 18/2000 Type 2 engine, plus probably some others, which I have yet to discover.
The spacer mast was made using a copper washer, two metric, female-female, in-line brake pipe connectors
(15 mm A/F hexagonal section), plus two valve rocker adjustment screws, which were cut to length and
through-drilled on a lathe (can be done using a pillar drill or vertical drill stand, but this is neater).
Alternatively, I could have used the hollow threaded portion of two defunct oil-pressure switches, small size
spark plugs or the domestic lamp fitting adapter, instead of the adjustment screws. An alternative spacer mast,
may be derived from the supplementary valve housing, with M10 x 1•0 mm male & female screw threads, fitted
to the brake master cylinders, of some post mid-1980s Vauxhall & Opel cars (European division of General
Motors).
With the appropriate skills, plus access to a lathe and other tools, one could fabricate a one-piece, 50 mm
spacer mast from a section of about 65 mm long, hexagonal, square or circular section bar-stock. This could be
machined and through-drilled, after which M10 x 1•0 mm male and female, non-tapered threads, could be cut
and tapped at either end respectively.
Noting that this, the other improvised spacer masts and the VW engine, crankcase oil-pressure tapping, are all
M10 x 1•0mm non-tapered threads, it will be necessary to use a copper or fibre sealing washer between the
spacer mast and the crankcase.
Ordinary 1way banjo fittings, are to be found on the brake master cylinders of some BMWs and rear-engined
Skodas. I also vaguely recall having seen one, forming the oil-pressure switch connection, to a VW 15/1600
Type 3 oil-cooler. There also exist, 2-way and 3-way banjo fittings, fitted either to the remote-acting vacuum
brake-servo units (might only be found on right-hand drive cars!?) or brake master cylinders, of some BMWs.
Some post mid-1980s, VWs and Audis, with water-cooled engines, have a slightly angled, 1way banjo fitting
with a 'through-feed-bolt', to fit two oil-pressure switches, to the crankcase oil-pressure tapping.
If the spacer mast is turned down on a lathe or filed, to a diameter of 14 mm, over the lower 20 mm of its
height, then it is practical to use the standard rubber boot cum grommet (VW part No. 021 119 957), to seal
the hole in the coverplate. As an alternative, one could use a short length of foam rubber insulation, intended
for 15 mm domestic water pipe, which will serve just as well.
As mentioned earlier, there are other available means of installing an oil-pressure gauge sender, one of which
involves employing a flexible hose with integral banjo fitting and remote mounting (illustrated in VDO's
installation instructions), such as those used by Andreas Frahm (see Neil Birkitt, "Moose On The Loose", VW
Motoring, January 1998, page 52) on his modified & renovated, 1972 VW '1600' Type 2, with 1976~79 VW
2000 Type 2 engine.
A similar installation, plus several other options, will be reviewed in detail (about ten A4 pages of text, plus six
tables, several photographs, wiring diagrams and other illustrations), dealing with VDO oil-pressure gauges &
senders, oil-pressure switches and installation adapters, for VW & VW-Porsche air-cooled engines, in the
instrumentation chapter of my VW technical book; if and when I get around to finishing it! In the meantime,
you might wish to refer to one of my recent technical articles, which shows a selection of the more significant
photographs:
Nigel A. Skeet, "How To: Fitting an Oil-Pressure Gauge Sender, Installation Adapter, to the Type 4 Engine", VW Camper &
Commercial, Issue 17, Winter 2004, pp44~45.
Some of the 1983~92 VW Type 2s, with water-cooled, flat-four, petrol engines, are equipped with an
additional oil-pressure switch, which closes at 0•90 ± 0•15 BAR, whilst certain other VW & Audi water-cooled
engines, manufactured since the mid-1980s, have an additional break-on-fall switch (VW Part No. 056 919
081E), which closes at 1•8 ± 0•2 BAR, incorporated into an electronic circuit, whereby a buzzer sounds, if
pressure falls below this limit, at engine speeds in excess of 2,000 RPM.
Either one or both of these additional switches, would be beneficial for the VW air-cooled engine, but I believe
that a system, similar to the latter option would be particularly useful. If available, it would also be desirable, to
fit a break-on-fall, oil-pressure switch, which closes at circa 4~5 BAR, to warn of excessive oil pressures; which
if anyone learns of one (preferably with an M10 x 1•0 mm screw thread), I would be interested to learn of it? If
necessary, one could adapt a break-on-rise switch, but this would require an additional circuit component!
The general topic of engine-oil pressure, oil-pressure gauge-readings and oil-pressure switches, is scheduled for
publication, in Transporter Talk (bi-monthly magazine of the British VW Type 2 Owners' Club), as part of my
serialised technical article, entitled, "Air-Cooled Volkswagens: The Case for Supplementary Instrumentation",
the first installment of which, should appear in the April 2006 issue; assuming all goes according to plan!
If anyone has difficulty obtaining 1-way M10 x 1•0 mm banjo fittings, I have a limited stock for sale or barter. I
can be contacted by email at naskeet@hotmail.com.
