Engine Rebuild (low compression)
 

So a few days ago I bought an 03 manual coupe with and engine that would crank but wouldn't start. Before I bought it I did a compression test only on the driver side 3 cylinders and got 30-40 psi in each cylinder. I brought the car back and started on an engine rebuild thinking it would be a head gasket issue. My coolant had a lot of chips of RTV and metal shavings in it, and once I pulled the heads off the head gasket looked perfect. The cylinder walls seem to be in good shape giving me no indication of bad rings. (however the car does have 190k on it) Valves also seem to be ok but I'm kinda new to this so I don't really know what I'm looking for. I probably should have done a leak down test before I tore the motor apart but it's a bit late now :(

I also feel like my compression tester could have been bad but I don't have another car to test it with and even if compression was fine I don't really know why the car wouldn't have started. I checked and the spark plugs were getting Sparks and injectors were flowing as well.

How would I go about checking if rings or valves are bad? Or could timing be an issue?

Any help would be greatly appreciated. Thanks

Valves you have to bolt the engine down to a test deck which is basically a flat plate with the proper bolt holes, then you apply air pressure through the spark plug hole and monitor it for any leakage. Usually this will be done by the shop rebuilding the heads after they're done with valves, porting, and decking them.

That's SUPER SUPER low compression, are you sure you were doing it correctly? If you were doing 7 engine rotations and it never went above 40psi on that entire bank I'm thinking it was something like the timing chain skipped a tooth.

Since you have the heads off already I would just do a quick rebuild on it, especially with 190k on it. Ball hone, new rings, water pump, check bearing clearances, new head gaskets. Then do a leak down and compression check after the heads are bolted down. You might as well fix everything since you have it partially tore down anyway. It's worth the couple hundred bux in parts so you don't have to mess with anything again. If you think that it's been over heated and has a warped head you can use a flat edge and check for warpage or have a machine shop check them first.