So i picked up this 91 vert about a week ago, the guy said the engine was seized.
I pulled the spark plugs out and grabbed the crank pulley to give her a spin, and it spun like any other non seized engine. A friend of mine said it should still make a sucking kinda sound to ensure that the apex seals are sealing. Since im new to the rotory world im not sure what the compression tester should read, or which plug opening ( leading or trailing) to attach the tester to....any help is apreciated!!!

 

Put the compression tester in the top (trailing) plug hole. You'll need to remove the schraeder valve in the tester, or hold down the bleeder button while cranking the engine over. Ensure the battery is charged fully, and prop the throttle open to give the most accurate results.

Since a rotary has effectively 3 combustion chambers per housing, you'll see the needle bounce for each one. If you don't bleed the pressure, you'll just end up seeing the highest value from one of the rotor faces. Ideally you should see 90-100+ psi per face. If an apex seal is damaged, stuck or missing, 2 faces will have 0 or low compression. An issue with a side seal can create the same problem on 1 face.

 

Be sure to pull the fuse to the fuel pump. You DO NOT want the engine to start while doing the compression test.

 

thanks for te info going to check it today, havent had time with all the damn snow and ice here. engine starting wont be a problem with the fuel pump out haha.

 

Don't just pull the fuel pump fuse.

Disconnect the CAS sensor so the ignition doesn't fire and give you a nice surprise.