Low Compression on 1 Cylinder, Interesting Problem (in the process of checking)

[Timechg]

I recently built a 6-bolt block (stock internals) with a 2g Head. The engine has almost 3,000 miles on it now. I checked the compression at various times to make sure the piston rings were seating nicely. To my great displeasure at around 1500 miles, cylinder 2 was reading about 110 psi, while the others were about 155 psi.

When I did the compression test, I did both the wet/dry test when the engine was at operating temp. Adding oil to cylinder 2 did nothing to raise the compression, so I assumed it was a bad valve/valve seat or something.

So, Today I had time and I finally took off the cylinder and did the following:

• 
  Poured water in the bowl with spark plugs in (using the jafromobile way).
  
  Poured Oil in each cylinder on the block.

So far it seems the valves are holding water fine and the oil in each cylinder has not went down at all.


What could be causing low compression on cylinder 2?

When I reassembled the head, I didn't check the springs. There were some springs that didn't seem to be going down straight as I compressed them (cocked one way or another with low resistance).

Could bad springs be the problem?

Can a burnt valve still seal properly?

I have another set of good springs/valves that I plan on installing in the new head, but I want to make sure I didn't miss anything else that it could be.

All/any thoughts are welcome

 

[BogusSVO]

The tip height could be off holding the valve open.

No a burnt valve will not seal.

If the springs are so bad, the weight if the valve would compress the spring to allow compression by, the follower would get kicked off at idle.

 

[Timechg]

The tip height could be off holding the valve open.

No a burnt valve will not seal.

If the springs are so bad, the weight if the valve would compress the spring to allow compression by, the follower would get kicked off at idle.

Would the valves still seal if the tip heights were off (holding the valve open)?

*can you elaborate on the follower would get kicked off at idle? I was having a weird problem where my vacuum would fluctuate between 16 mmHg at times (running choppy, no vacuum leaks) and then it would smooth out at random times and would read 20 mmHg.

^Could this be a symptom of that? I plan on replacing all of the springs, but just want to make sure everything is checked before putting the head back on (don't want to be pulling it off again).

 

[BogusSVO]

No if the tip height is too tall, when the HLA pumps up, it would crack the valve from the seat = No seal

Kicking a follower means it is off the top of the spring and HLA.

If you are getting a vacuum flux from 16 to 20, then that is a valve seal issue.

Try fluid testing the head like this.
http://www.dsmtuners.com/forums/newbie-forum/420313-how-fluid-test-4g63-cylinder-head.html

What springs do you plan to install?
What springs are on there now?

 

[Timechg]

Sorry for the late response, I put some good stock springs back in (next build will have some stronger springs/retainers etc.) I just wanted to get back on the road asap.


Thanks for the fluid testing article, I used the other method where you put the water in the combustion chamber bowls and it seemed to hold. However the other method I saw some immediate seepage out of 2 exhaust valves on cylinder 2, and one exhaust valve on cylinder 1. I went ahead and lapped the valves again (with a drill this time) and redid the liquid test.

Compression is back to normal and the vacuum pressure is holding steady at 20 mmHg.