I’ll be able to get back to the motor either Sunday or Monday. Been out of town. I’ve got the rockers and valve springs off now. I’ll reassemble, add compressed air and remove the rockers. That should tell us if the rings are good or not? Is it possible for valve seats to go bad without falling into the cylinder?

 

I just want to know if you still hear air rushing back through the throttle body when you pressurize #4 cylinder with both rocker arms off.

 

So I pressurized #4 to 100 psi and air poured out of the it’s intake (circled in the pic attached). It was also coming out of the space where you can see the camshaft/lifters (not sure if that has a proper name…I included a pic with that circled too). I used a rubber tube to listen to various places, and didn’t hear any coming from the exhaust, but some noise from the dipstick tube (not nearly as pronounced as the intake). I turned the motor just to see what would happen if I pressurized it at different positions. (I know it shouldn’t matter with the rockers off, but I was curious). Seemed to me the intake leak wasn’t as bad when I turned the motor 90 degrees. Doesn’t make sense to me, but I’m already pretty confused.

Leaking enough air to easily feel with my hand.

Noticed air noise from here when I used a tube to listen for leaks elsewhere

 

OK - #4 intake valve is leaking for sure. Pull head off for inspection.

 

I figured that would be the next move. Question, moving forward…if we find a broken valve or seat, is it possible to replace/repair without replacing every single valve/seat? I’ve heard that if you replace one, you should replace them all…and that the driver’s side head is much more difficult to remove (and that maybe even piston rings should be replaced). I’m not prepared to do a complete engine overhaul. Is that going to be the only fix?

 

It may be possible to fix just one valve but need to inspect for damage to piston. Probably has a bent valve. Forget about the rings.

#4 cylinder is passenger side head which is easier, but do the same test without rockers on all cylinders before disassembly. Then you know other cylinders are ok. Yes I understand this needs to be a budget fix. Shouldn't be much more than cost of gaskets + valve and oil unless valve seat needs major work. Irregardless, the engine isn't driveable as it is.

Start soaking those exhaust pipe studs with wd40. Exhaust manifold has to come off to get at all the head bolts.

 

So the leakdown without rockers on other cylinders was not particularly good. #1 cylinder was leaking as badly as #4 from its intake. #3 and #6 leaked mildly from their intakes too (I suppose an old motor is going to leak some?)
I used my spring removal tool to work the #1 intake spring up and down a few times…then the leak was better, which means it might not be seating properly? #5 could be heard a little from the dipstick tube. There does seem to be a lot more in the way of removing the driver side head.

 

And now we are back to conflicting results between having compression (at all) vs intake valve leaks that you are hearing.

Need to get a leak down tester apparatus - dual gauge setup. This supplies 100 psi through a 0.040 orifice into the cylinder and then measures the resulting pressure in the cylinder as it leaks out. The more leakage out of the cylinder past rings or valves, the lower the test pressure. 20-25% loss is acceptable on an old used engine. I have a race engine that is between 3-4%.

 

This is the one that I have

You adjust first gauge to 100 psi with air flowing through apparatus into the cylinder and read %leakdown on the second gauge. Make sure air compressor can maintain 100 psi in.

 

Didn’t mean to leave you hanging. After discovering a second cylinder leaking badly in the other bank, I’m seriously questioning whether I want to move forward. It basically means a complete valve job (#1 was leaking out the intake too…unless it was just ‘stuck’ from me turning the motor slowly, manually many times). I’m still deciding… I’ve invested so much time and energy into it already. How much more of a job is replacing all the valves, guides, seats, etc?