I have a 97 chevy 1500 that I halfway rebuilt. I installed new gaskets, bearings, and a new crank. I had a spun bearing, and it ran perfectly fine beforehand. I installed it and it runs horrible, like its missing on a couple cylinders. itll run if I give it gas and that's struggling to even stay alive too.
It started leaking antifreeze out of the driver side head where it mates to the intake manifold also. well, I did a compression test on the driver side head and got
1-120
3-150
5-0
7-0
also verified that the tester was still working by using it on 1 again, got the same numbers. This was done on a dry test with wot. if none of the pistons were removed at all and the engine ran fine before hand, is it possible the head warped prior to installation? maybe improper head gasket installation?
thank you for the help, and im sorry about this being my first post. very pressed for time in getting this truck fixed now.

 

Maybe valves stuck open ?

 

That's what I'm thinking. Since it's absolute 0 I'm gonna do a leak down test when I get a chance. I gonna back off the valves first. I only did a half turn past 0 lash on all rockers, so I'm thinking something's bent or maybe stuck like you said

 

The leaking anti freeze makes me think the intake gasket probally didn't get installed correctly or was damaged during installation. Do these intakes require a dab of sealant on the corners like the old school carb intakes do?

 

I would apply compressed air to the cylinder through the spark plug hole while the valves are backed off. If it is leaking you will hear it. It will leak out the throttle body, tailpipe, or crankcase.

 

Just as Gadgetized said, by putting air to each cylinder with both valves closed you can listen and be able to easily hear if air is rushing out the exhaust or the throttle body, which would tell you if you had either an intake or exhaust valve issue. If you pull the oil fill cap and hear air rushing out you know it is blowing past the rings and down into the crank-case. It is somewhat reasonably common to see burnt exhaust valves on older higher mileage SBC’s, especially if they have been worked such as towing, so I would expect you to hear it blowing out the tailpipe, but you won't know without 1st testing things.

 

Sorry it took so long to reply, but I want to do a leak down test. I just haven't had the time. I know that a leak down will pinpoint the problem. I just don't understand how valves wouldn't seal or rings would be bad when neither were touched when the engine wasn't apart. My best guess is the I'm gasket is leaking compression as it's leaking antifreeE through the gasket at those two cylinders or bad valve adjustment. I'm off again Tuesday so I'll let you all know after the leakdown