VERY CONFUSED!!! INTENSE KNOCKING SOUND!!!

[EzioWolf]

Alright so here is my situation. I recently had just brought my 1990 NA Z32 back to life about 2 months ago. she ran fine up until one morning i tried to crank her over and she had the loudest knocking sound i have ever heard. It was instant and it didnt do any sort of knocking AT ALL any time before that. It sounded non other than engine knock and I was 100% sure i needed a new motor.

So, I left her alone for about a week and a half saving up money for a new motor and i figured "hey since im on the market for a new motor I want to see how bad the interference is". I pulled out my coil packs and unplugged my injectors because I didnt want it to actually start on me and go on the fritz. Then i turn the engine over a few times and get absolutely no abnormal feed back. Tried it again and holding the ignition for about ten seconds and still nothing crazy, not even a faint knocking, just a solid turn over every time.

Naturally I got curious and decided to plug up my coils and injectors. It started up like normal the first time. The second time it knocked for about a half second and started up fine. I heard absolute zero knocking while it was idling. There was a solid and consistent belt squealing issue while revving the engine though.

Please let me know any thoughts or questions about my situation.

P.S. I obviously will not start it again seeing as I might possibly still have an ok motor?

[AZhitman]

Sounds like a broken belt tensioner. Get under the hood and inspect everything very closely. Take the belts off (they probably need replacing anyway). Wiggle the pulleys. The squealing belt is your clue. Start it with the belts off, rev it, and see if the knocking is gone. Obviously, don't run it for more than a few seconds... Let us know what you find!