Celica Forums General Discussion Engine and Performance Overreved 2ZZ, no comp., told it likely had bad rings from start

I overreved my engine (yeah, yeah, misshift). Car still ran and reasonably okay at that (only dared to push it up to 3k though) but idled badly. Compression test came back as 9-6-5-4.

So I came to terms with having to rebuild the head, brought it to a shop that would take on the job and waited.
They called me back, apparently it only jumped a tooth and thus shouldn't have bent anything. So a new chain, water pump had a bit of movement to it and bits and pieces along with that. Okay great, so be it.

Well they did the chain and it still has no compression.

Supposedly it may have had bad rings to begin with, even before my mishap, because with bent valves it would barely start and run at all. So since a full rebuild just isn't worth it, I should maybe find another engine and swap over the new parts.

So that's where I'm at and I'm not sure it makes sense to me. I didn't have the car for long, no idea what its actual compression was before or how a healthy 2ZZ should run, but it really didn't feel it was missing anything. It pulled easily, hit lift, got up to speed etc. It came with dyno sheets from 2017 that put it just a few kW below the rated 141. I chatted with the previous owner that didn't need to hide anything just on the fact that he was several countries away and wasn't even who I actually bought the car from when it was imported. I'm pretty confident that I alone broke it.

After talking with some others I think I still have some bent valves in there. Shouldn't bad piston rings be pretty obvious by the PCV too? I heard about a leakdown test, but I feel like they would've tried if they had the tools or knowhow for it.
So I don't know. I'm thinking to just tell them to pull the head and see what they find. If the valves are actually okay, well then I guess I'm looking for a new engine. If not, maybe just rebuild the head.
But I keep coming back to the idea that just maybe finding another engine is solid advice no matter what's wrong with mine. Even just the head rebuild must be some 1000€ at the least.

Just looking for opinions before I make a choice I guess. Feeling a bit lost atm.

Any luck yet? Mine has been in the same situation for over a year waiting to get a couple of home moves out of the way then the house I was renting burned so another delay. Mine is in my garage right now and I just pulled out pistons 1 & 4, middle ring is sharp, oil rings appear to be stuck in the pistons. Did you just scrap the head or get a new engine? Where did you get you parts and/or engine from?

They took the head off in the end - all exhaust valves were bent. Installed new valves, chain, gasket, etc. Most parts were ordered locally, only had to get supertech valves from ebay as they were the only ones available. It runs now, although there's an annoying vibration around 1100rpm that I'm not sure I'll ever find a fix for. Probably should've just gotten another engine in retrospect. Doesn't sound like this will be much help for you since you're already at the stage of pulling pistons out.

Vibration at idle or low RPM may be caused by uneven compression in the cylinders.

I rememeber compression across 4 cylinders must be within 10% of each other. Larger vatiations cause engine to be hard starting, idle and run rough at low RPM.

The vibration will damage all engine mounts and cause other problems.

Oddly it mostly smooths out once it gets down to around 700. I would expect any imbalances to get worse the slower the engine is turning, not just stay within a specific range, but what do I know. There are no other apparent issues, it starts and idles fine. Anyway I did suspect uneven compression as one of the possibilities, but haven't gotten around to do a compression test yet.