Crank not start issue

Okay, I hope it works for you. I think you'll be able to get it taken care of. It's a bummer she ran it so low on oil. Chat soon.

Thats not good. If the chain jumped more than just one or two teeth like what it first seemed, the pistons could have hit the valves. Since the pistons on these engines are straight down, you put a long screw driver down or thin pole until it rests on top of the piston and turn the engine over very slow by hand until the pole moves to its highest point, once it's at its highest point it will start moving back down then you know you're at TDC, for the #1 cylinder the marks on the crankshaft pulley will be lined up too. I was hoping the chain had only jumped 1 or 2 teeth because there was a cylinder back firing through the exhaust, it must have been the one cylinder doing that, Best thing you can do now is rotate the engine by hand, get the number 1 up to TDC and if you have one of those compression gauges that you can take the gauge off and attach an air hose to it. You can put some compressed air into the cylinder and see where it's leaking out. But remember you're not going to have compression right now. The valve timing is off for the most part. You were doing a cranking compression test I assume? Sorry for my crude drawing below, but this is how I would find TDC with a loose timing chain. Crank it over by hand.
Also, you didn't do any damage during your compression test, whatever damage was done, happened when the engine quit running.
The mark on the Harmonic Balancer is for the #1 TDC. And you probably have the valve cover off. Every 1/4 turn of the camshaft is the next cylinder at TDC. So, when you have the 2 cams up on the #1 TDC, if you turn the cam only 1/4 turn, you next cylinder (#3) is up on TDC. The firing order is 1-3-4-2.

I doubt you have any holes in pistons, bent valves is much more of what I would expect to see if the chain jumped far enough. It takes quite a lot to break a piston, unless the head of a valve actually came off. At this point with that car, I would probably take the timing cover off and inspect everything, since you already know it might be more of just a loose chain. How high was the compression on the #3? I picked up a 2004 Camry too, if I can just find a front Air/Fuel sensor for it that's not $300.00.

Yeah, that's cylinder #3 that hit 125psi is a bit strange with all the others at 0. At least the valves aren't bent in that one, or it could be that the particular cylinder happened to have the chain slack on the opposite side, so the cylinder sealed up. But it's tough to tell until you get things lined up and see how far off it is. I don't know if you use oscilloscopes, but it's a great way to check valve timing, either doing in-cylinder pressure testing of scoping the cam and crank position sensors and finding a known good waveform for that car (which I can get for you). And comparing the signals. But using a scope takes some practice, If we're going to be exchanging parts id better email you about that instead, but I'll still help you with diagnosing the Camry here. I am curious to see the condition of the engine. I'll see if I can find any other information about the valves, if that's an interference engine or not. It would be really great if it was not.

Okay, on Toyota's end, this is a very unwise build. On the V6 Camry's from 1990-2006 they are not interference engines, but all 4 cylinder Camry's from 2002-2021 are interference engines. It's very disappointing news. It says some engines with timing belts are non-interference engines but if it has a chain they are. I guess they think that nothing can go wrong with a timing chain setup. Also says the only time a chain setup will have an issue is if the oil level goes too low, which is what happened to yours. So, you will probably run into belt valves. The only good news is that it only has one cylinder head to deal with. It gets real expensive when it comes to dealing with 2 heads. Do you have the 2AZ-FE engine in that one?

You're exactly right, they act like nothing will go wrong, it's not even the chain stretching so much as it is the chain guides failing, once they break at one of the 2 bolt locations, the guide is flapping in the breeze. As for scopes, if you have a laptop, Pico has a scope 2204A, it's not an automotive scope but it's just over a $150, 2 channel. I'd be glad to show you how to use it and tricks that can save you having to tear motors down to find faults. Their software is free too, you could download it right now to try it in demo mode. I use my scope for everything. And sorry for giving you bad news, it's the worst feeling telling someone there's a major issue with their vehicle.

Oh wow, I wasn't expecting it to be that bad. I have seen more rods coming through engine blocks this year than ever in my life. I wonder if this has something to do with oil quality or some other outside reason besides normal wear. It did have a lot of miles on it, but I've worked on some of these that are pushing 280,000 and the engine block is the only sound component left. Thanks for the update. I'll keep that picture for the archives. Sorry to hear the bad news, but thanks for the picture Jeff.

Honestly, I don't know if that scan tool has an oscilloscope built into it, but I saw a video yesterday that was about how some of these aftermarket scan tools can give incorrect data. I posted the video below. But for oscilloscopes I use a Pico Scope, it's a pc-based scope, you can actually go to their website and download and run the scope software. It just runs in Demo mode until you buy one of their scopes, but the Pico does so many different things it's my go to oscilloscope for things that need a very good in depth look at. I also have a handheld Hantek 2D72 which has a multimeter, a scope, and a signal generator built into one. I use that for grabbing quick signals. When I don't want to get my laptop out. But go to PicoTech.com and try the software. It can actually decode CANBUS network data packets. Plus, a million other things. For scan tools, I have an Autel, a TopDon, and a couple older scan tools. The Autel is pretty amazing. Snap On is just so expensive for almost everything they sell, not saying they are not any good because they are, but you pay a lot. The Pico scope also has 3 or 4 pdf files on user information. So, it's easy to learn. I also recommend if you're going to get into using a scope, buy Attenuators with it, at least a couple 20:1. They step the voltage signal down to protect the scope, but you just set the scope on a 20:1 attenuator and it will show the correct voltage. There's a couple of pictures of the Pico 6 software I use, and a second pic is a couple of my own pressure transducers I built that I use for fuel pressure and in cylinder pressure testing. I think for the price of the Solus you could get a couple of other diagnostic tools. If you wanted lessons on using a scope, I would have to do that on the side. I wouldn't be able to do it on here.

https://www.youtube.com/watch?v=mags7bhzCR4