ST205 motor and trans into a ST165

Write ups and tutorials for maintenance and modifications.

ST205 motor and trans into a ST165

Postby lt2fire » Wed Jan 16, 2019 11:09 pm

Ok so i've been reading what info I can find out for this swap.

Just want to make sure I have this right.

Engine and trans are drop in.

I can reuse the 165 sensors and wiring harness and just use this jumper to the 205 ecu ... ucts_id=30

AC lines will need to be custom

Is there any other huge hurdle to overcome to make this work. Thinking mine is going to need a new engine sooner or later and would rather upgrade than just fix this one.
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Re: ST205 motor and trans into a ST165

Postby freddie » Thu Jan 17, 2019 1:05 am

In the swap there are no big issues, but lots of little ones like having to make little brackets to mount things and so on.
Like engine mounts, you need to use the 165 type as the 205 ones do not bolt onto the body cross member (bolt holes
do not line up.) And the 205 mount at the cam belt end of the motor definitely will not fit Lol.

I used the ST165 Ac compressor and the pipework, therefore no problems re-fitting it. (maybe a little bit of light bending
here and there) There was a second reason to re-use the 165 compressor was that it had a simple clutch electrical system
that my aftermarket ECU could control.

The main thing to consider is that the ST205 ECU operates differently to that of the 165 and 185. Most notably is that there
is no MAS unit. The bases of the 205 ECU is MAP (maximum air pressure) and MAT (manifold air temperature to measure for
air density) The ST205 distributor is different too. Under the rotor plate there is a cam system trigger wheel for crankshaft
positioning and cylinder firing info for the ECU. What I am saying here is very rough and I am sure that there are other
members that can explain the system better.

The 205 front axles are too long, so you need to install the 165 ones.

I used the ST205 Water to Air turbo cooling system. The Heat Exchange Radiator from the 205 is big and again I had to make brackets
and do a bit of jigging around, no more than that I would have to do with a A to A system. Yep I used the 205 pump as well.

There are some other little bits to do, but all the info and help you will need is here on this forum, lots of write ups.
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Re: ST205 motor and trans into a ST165

Postby black88alltrac » Fri Jan 18, 2019 3:57 am

use the st205 engine harness and mate it to the st165 body harness. there arent that many wires to connect, its just a little bit of a headache to figure out which wire is which using both wiring diagrams but has a good thread showing what each wire in th st165 fuse box is and then you just find the corresponding wire for st205 harness (i always get a swap that has the full harness including the fuse box its ok if the wires to the fusebox are cut.)
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Re: ST205 motor and trans into a ST165

Postby freddie » Sat Jan 19, 2019 2:29 am

As I wanted to use an aftermarket ECU many of the wires in the wiring harness needed to be changed.

What I did was to purchase 2 sheets of thin cheap fibreboard You know the brown stuff and made a flat table top approx.
2.7x1.2 metre (say 9X4 ft) (I used 2 pieces and joined them together) I positioned this top on top of another table
with access all around it.

Next at one end of the table top I positioned the ECU and fixed in position with a bit of double sided tape. Then with
a piece of string (as a flexible measuring tape) I measured the distance from the ECU to each components. and marked
/wrote with a black felt tip pen it's position on the table top. For example the location and distance from the ECU to a fuel
injector and so on. I continued this process until I had all the electrical components connection located, plus the new ones
for my new ECU. Locate the 2 fuse boxes on the table. Oh also the interconnections into the second main 165 harness. I
wrote notes to myself and location of additional wires and modification of wires for the A/M ECU (plus a few extras) Also
I noted things like the 205 ECU (and my A/M ECU) requires 4 wires at the O2 sensor.

Now comes the new wiring harness. I opened up the 205 wiring harness and transferred each wire one at a time connecting
the wire at both ends. Where possible I re-used the the existing terminals/plugs and chose to cut the wire and solder the join
and put a bit of shrink rap insulation over the join.Do one component at a time and make sure it is connected at each end.
A good example of this I did all the fuel injector together with new connectors and connected the other end to each ECU pin.
Done! The secret is do one component at a time and finish it, do not have any wires laying around unconnected.

When it got a bit messy lots of wires I taped them together and onto the table temporarily with a bit of masking tape.
Wires to be interconnected into the second fuse box or harness I labeled each wire with a piece of masking tape.

After checking everything and double checking. I now started to add the insulation. I chose to use the plastic spiral wrap
stuff of various sizes and good quality electrical tape. And it is done and all wrapped up Lol.
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