I am planning to swap the engine from a 90 Legacy AWD wagon into my 91 Legacy AWD wagon. The 90 is an automatic and the 91 is a manual transmission which I want to retain. Would like to know if there are any problem areas I should watch out for.

For example, since I am keeping the manual transmission I will need a pilot bearing. Is the pilot bearing in the flywheel or the end of the crankshaft?

Also I assume I should keep the ECM module that goes with the manual transmission, i.e. the 91.

Also the 90 has cruise control--the 91 does not. Any problems here?

I know the pilot bearing is in the flywheel, and you will need a slide hammer and a special puller to get it out. I'm not so sure on the wiring setup of the engine, though I imagine that the difference between the 90 and the 91 remains in the computers, the engine should be the same through and through. Still, let's here what other more experienced people have to say on that matter. PS, considering how much of a pain it is to replace, unless you have a really new one, I would replace the clutch, pressure plate and release bearing, and make sure the release fork is in good condition (I broke one before). Hope this helps out!

Actually....you're going to run into a few issues with the electrical.

 

The 90-91 MT's & AT's had different injectors, MAF's, coil packs, ignitor, and IAC valves. The main reason being is that the AT's have a JECS ECU, while the MT's have a Hitachi ECU.

 

Here's what "I" would do. Take the ECU out of the 90 legacy, and swap it into the 91. You'll need to make sure you swap the AT MAF & ignitor over to the new setup. Also, the "diamond" coil pack from the MT cars tend to handle a little more power, so I'd keep the diamond coil pack and put it on the AT motor.

 

If you do all that, you "should" be fine. The ECU's wiring has an AT/MT identifier pin. Depending or not if this pin is grounded, it tells the ECU that it's an AT or MT. So the wiring should be good....and you'll just have to plug in the 90 ECU.

 

I have a technical packet for the 90 legacy. It lists the differences in sensors. I'll verify that the sensors I listed are the only things that are different.