190 compression to 0 overnight-all 4 cylinders

[skymx]

Here's the scenario. I just finished my rebuild on my 92 AWD Talon. Complete motor rebuild using Ross Pistons and reseated all the valves in the head. Drove it to work, got a little warm, stopped, pulled over, refilled anti-freeze, (about 3/4 gal low) and put a new clamp on the hose that was pissing. As I drove home, (60 miles on the motor at this point) I noticed there was no power, idling was rough and jumpy as well, like the timing was off. My first thought was the worst, I thought I scorched it. I continued home (temp stayed normal the whole time) and immediately did a compression test. All four plugs looked perfect, and the compression for all cylinders was between 190-200. That was all I needed to sleep well that night. The next day I did a compression test and every cylinder is at 0. I am extremely puzzled by this, what can happen when the engine cools overnight to cause this? It's like someone magically removed the pistons or opened all the valves. Any thoughts are appriciated.

 

[philipkrotch]

that is very strange. i burnt 4 valves and i lost compression instantly. it ran fine, but under boost it didnt do shit but run like hell. wow, i am really stumped.....

 

[turbohappy]

Is it possible that you broke your gauge somehow? That doesn't make much sense.

 

[skymx]

Used 2 different compression gauges. They're not broke, the engine cranks over almost effortlessly. The crank is turning because all the belts on the front of the engine are turning. I'm stumped. Just looking for a little help for something I've overlooked before I start to tear it apart.

 

[eclipse90gsxt]

How does the car run? That is kinda wierd, did you heat the car up again to do the morning compression test? Thats damn wierd dude.

 

[SpeedFreak03]

Could some of your valves be stuck open? That would cause 0 compression.

 

[boostedinaz]

As I look at it there are two pissibilties. Did you check the timming? My buddies car did the EXACT same thing yours did. Ran rough for a bit then the next morning wouldn't start and had no compression. He skipped timming and all the intake valves were bent. Check the marks and then pull the valve cover to see if any of the rockers are lose. If they are then you bent that valve and maybe more.

The other could be that the head or the head gasket are not sealing after it got hot. Aluminum and cast iron expand and contract at different rates so maybe the extra heat and then cooling is making it hard for the motor to seal. Not likely but on option.

Other than those I dont see any reason for them to not build any compression after having a shit load. Perhaps something with the rings but to go from 190 to 0 is very weird. That would usually make the reading very odd, like 140-120-190-130 not dead across the board. Same for the head gasket weird numbers not all dead.

Michael

 

[skymx]

Thanks for the thoughts guys. I did check the rocker arms tonight, bad news, intake valves are bent. The only conclusion I can figure is that the timing jumped slightly, enough for it to run like shit on the way home, when I did the compression test when I got home, it must have jumped again, this time enough to bend the valves. Well, back to the garage to tear it apart...again :thumbdown Anyone wanna sell some valves?