T25 Subaru engine swap – Part 3

11/7/07
14:38
Page 86
T25 Subaru engine swap – Part 3
In this, the final part of our series on installing a Subaru Legacy engine in a
Type 25, we take a look at the cooling system and our first trip out on the
road. Be prepared for a life-changing experience…
ell, we’re almost there! Last time around we left you with
the engine bolted into place for the last time and about a
day’s work ahead of you to finish up before hitting the
highway. But be patient – while the end may be in sight,
don’t try to rush these vital last steps, in particular the
modifications to the heating and cooling system.
W
Final fit
You need to start by installing the RJES-modified reversed coolant outlet
manifold. This allows the engine’s top hose to point towards the radiator
pipes in the front right-hand corner of the engine bay. In the Subaru
engine bay, the radiator was located in front of the engine – but in a VW
installation, where the engine is reversed, it is effectively located behind
the engine (in fact, all the way down at the front of the T25).
Take a good look at the condition of the cam-belt – it’s something
that is easily replaced with the engine out of the vehicle, but if you didn’t
replace it before installation, have a second look to make sure of its
condition. If in doubt, replace it now.
Refit the induction manifold, complete with throttle body and associated
linkages. Don’t worry about the throttle cable, though, as you’ll be
replacing that in a moment.
Next up is the heater bypass adaptor. This is a vital component on a
Subaru conversion. Without one, your engine will overheat as soon as
you turn off the heater, as you’ll be cutting off the flow of water. The
RJES-supplied adaptor is a simple bridging piece that allows a certain
amount of water to flow through the heating system at all times.
You can now install the original header tank in a new location in the
front right-hand corner of the engine bay using the RJES bracket. This
requires the drilling of two holes for self-tapping screws, but apart from
that it is straightforward.
Connect up all the coolant hoses, following the RJES coolant circuit
diagram which is available as a PDF file on the CD of fitting instructions
supplied with the conversion kit. One of the nice things about the RJES
conversion is that there are no cheap convoluted hoses used, which
adds to the ‘factory-fitted’ look. Be aware that there are some very badly
designed coolant circuits available on the Internet, which will be very
difficult to bleed air out of, so follow the instructions carefully.
The original fuel pump is no longer used, so you need to fit a new
high-pressure one, along with a filter, to the inner side of the right-hand
chassis rail. Rubber mount the pump, otherwise it will be noisy. In fact,
the sound of the pump running when you first turn on the ignition is one
of the giveaways that all is not stock! You should replace the whole VW
fuel pipe with new 8mm-bore fuel-injection hose to SAE 100 R6, and add
a return hose to the tank. Fortunately, even T25s with carburettors
already have a fuel return fitting in the tank.
Connect up all engine wiring, following the instructions – it may look
complex but the modified loom is easy to install and should present no
problems – even to someone terrified of electrics! A new gearbox earth
strap is highly recommended, too.
Next you can fit the RJES throttle cable – a direct replacement for the
original – followed by the induction system. The plastic inlet pipe from a
1990–1994 Subaru Legacy fits between the throttle body and air-flow
meter, while an aftermarket cone filter and adaptor is the simplest filter
installation in the available space. Finally, connect the breather pipes to
the induction pipe.
Incidentally, it’s worth mentioning in passing that the Subaru
86 u l t r a v w. c o m
1.
There’s not much to give the game away. To the casual observer it
still looks like a stock Type 25 but, as the local Saxo boys have
discovered, it’s a rocketship away from the lights!
2.
Reversed water manifold is necessary to allow the Subaru engine
to function with the original VW cooling system. A detailed PDF file of
the cooling set-up is included in the instructions from RJES
3.
Everything is so easily accessible – and it’s hard to think that the
Subaru engine is an afterthought, so to speak. All that remains to be
fitted here is the inlet ducting, and then it’s time to tidy up the wiring
and hoses prior to that first test drive
Words: Richard Jones Photos: Keith Seume and Richard Jones
086UVW48