What to check on used long block?

[E.Murray]

I found a long block out of 52k mile 2013 car at a dealership. They said the car was a trade-in that was smoking, so they replaced the engine. Seems a little extreme, but the tech I talked to (the guy who did the work) just kind of shrugged. He said he thought the engine was ok and got the approval to sell it. So I jumped on it.
That was a few months back and it's just been sitting in the garage since then. I finally got around to checking it out and it seems to be fine. I did a leakdown test and cylinders 1, 2, and 4 are all at 16%, with the only hiss coming through the intake valves. If I cover up the intake port, the leak goes to virtually nothing. Cylinder 3 shows 22% and, again, only past the intake valve. Obviously, this is a cold motor. I can see that the valves are dirty, so I soaked the #3 in some Seafoam, but the reading didn't really change.
So, finally, here's my question: what else can/should I check? I think the plan has changed, so I'm on the fence about using the motor. I was going to just sell it as-is on here, but found out I need 100 posts first. That's probably never going to happen since I only post when I actually have something to say and it will take years to have 100 things to say... So maybe I'll keep it. Either way, I want to know what I'm looking at without a bunch of disassembly.

[Bexar]

I don't think soaking it would be enough. I think you'll have to get into it and pressure blast with media. As far as that goes

[E.Murray]

Originally Posted by Bexar I don't think soaking it would be enough. I think you'll have to get into it and pressure blast with media. As far as that goes

Which puts a bunch of stuff in the cylinder specially designed to be abrasive. Unless there's a safe way to do it?
What's the best way to get the valves clean? I let it soak, then blasted it out with a rag wrapped around the air nozzle (to catch all the black crap). Learned about the rag the hard way...

[Bexar]

Originally Posted by E.Murray Which puts a bunch of stuff in the cylinder specially designed to be abrasive. Unless there's a safe way to do it? What's the best way to get the valves clean? I let it soak, then blasted it out with a rag wrapped around the air nozzle (to catch all the black crap). Learned about the rag the hard way...

Pull off intake mani
Google "cleaning valves mazduhspeed3"

[E.Murray]

Originally Posted by Bexar Pull off intake mani Google "cleaning valves mazduhspeed3"

Ok. I'll try to do that this weekend. I didn't know there was an established way to do it. Anything else I should check while I'm in there?

[Bexar]

Seems like it was pretty early in it's life at 52k. Maybe see what the oil looks like if you haven't already. It will be interesting to see how bad the valves are .

I mean check the pan for debris if you're messing around with the engine anyway (and it's out of the car). Could do a timing chain change.

[E.Murray]

I pulled the pan off last night and there is no metal in it.

[Db09ms3]

Nice. Check the chain stretch from the valve cover.

[E.Murray]

Originally Posted by Db09ms3 Nice. Check the chain stretch from the valve cover.

Good tip. I’ll do a search on how to check that.