Switch to full style
General Chat
Post a reply

ST-185 Engine Swap

Mon Apr 15, 2019 1:00 am

Looking for some advice about engine swaps. My original engine overheated and loss compression at 205,000 miles. It was rebuilt by Toyota and the original owner at 139,000 miles for the same problem, hence not looking to rebuild. I am not looking for additional performance, just a reliable set-up. I know that there are various engines that would work, but looking for the least amount of modifications to get an engine in. I know that a 2nd gen JDM Celica Alltrac engine would fit with a JDM ECU and some lengthening of the wiring. What other options are available and how much modification is required. Thanks in advance.
Members don't see the above ad. Register now

Re: ST-185 Engine Swap

Mon Apr 15, 2019 6:48 am

When the previous owner had a shop install a gen3 into my st185 the shop used the harness from the gen2 on the gen3. I would think it is the same thing on a jdm engine besides the egr valve plug. Then just replace the seals and timing belt and related parts if you want and drop it back in. I would find a gen3 or newer but the newer ones will require more wiring or a patch cable

Re: ST-185 Engine Swap

Mon Apr 15, 2019 6:01 pm

I know people have swapped to ST205 electronics with minor changes to their 185 harness, so a JDM 205 engine using your 185 harness to run the 205 electronics would be a good bet. Alternatively you could run a JDM 205 or 185 block with your current electronics.

Re: ST-185 Engine Swap

Mon Apr 15, 2019 7:50 pm

To re-pin the harness it's a bit of a pain but I've done it a few times on my 91 all-trac. Once to use a 92-93 SARD ecu then back to the 91 and then I just got a berk patch harness. It's like $100 but headache free and makes it plug and play besides adding the MAT and IAT sensors

Re: ST-185 Engine Swap

Mon Apr 15, 2019 9:57 pm

The least amount of modifications is using a JDM engine of the same revision as yours. What year is your car?
You can use your wiring and ECU.
The only issue would be if you live in Ca or somewhere EGR is essential. Then you would need to swap the head/intake manifold and EGR stuff from your engine so you could use the EGR.

Re: ST-185 Engine Swap

Wed Apr 17, 2019 7:38 pm

This swap would be for a 1992 Alltrac. This is not a CA vehicle, so no exchange of head needed. Good reliable engines are getting harder to find of that vintage. That’s why I was trying to research 3rd and 4th gen JDM engines, and perhaps wiring harnesses to make the job easier.

Re: ST-185 Engine Swap

Sat Apr 20, 2019 5:17 pm

If you swap in a gen II engine it will literally be plug and play (if you get a pre revision engine you use your alternator/harness and knock sensor). If it's a post revision you can use the ECU [it plugs right into yours] and will have slightly more power. Pre revision if you want to use the ECU a few pins will have to be swapped at the ECU. Several pins won't just swap. Either way you don't need the "new" harness.

For the gen III vs gen IV the 3rd gen wiring will be much easier; you can use your current harness. You have to swap 5? pins at the ECU connectors and extend/change 2 connectors, the EGR temp sensor has to be extended to the Manifold Temp Sensor and you have to use the AFM connector for the Intake Temp Sensor. But you'll either have to build a (simple) circuit to defeat the intercooler pump fault circuit or use an MR2 ECU [may require slightly different wiring?).
You will also need to install hoses, pump and a heat exchanger for the intercooler or install a front mount.
Most engine add on parts are the same [sensors, accessories].

The gen IV wiring is different, but you'll have a top mount IC. Though IIRC you'll have to slightly cut your hood to fit it underneath? Or fit a front mount. Plus more parts are different.

That's all I can think of off the top of my head. I may have missed something.

Either one should mechanically bolt in just fine. If the gen IV accessories are a problem you should be able to use yours. Gen III are bolt in. You won't want to use the Gen IV transmission, you will want the Gen III transmission.
Post a reply