Your opinion is greatly appreciated

[fabio420]

Alright here's the deal. A while back this KAT blew. We didn't know what was wrong, so we rana compression test. The compresion started at 140 in cylinder 1 and decresed as we went back ending with 30 on the last cylinder. We ran another compression test after putting in some oil to check for the status of the piston rings. No change. So we took the head off figuring its a blown head gasket. the gasket had oil in it as did the spark plugs, and looked a little shredded around cylinder 4. So we rebuild a new head for performance( it was gonna get done anyway later) and swapped all the components in it. Finnally got everything in and put it back together. I used platinum spark plugs pre-gapped for temporary use(could get NGK right away). So after averyting was reassembled, we turned the engine over and got nothing. It turned and made the sound you'd expect, but almost with an uneven timed firing sound. Checked the compression and got 160,55,125,0. So I figure the rings or ring lands are gone. But I'd like to hear from people to make sure we're not overlooking anything. Please, we could really use the help. P.S. I really don't want to, but I'm afraid I might put dynamite up the exhaust if I don't fix this car soon.

[Import_Ant]

that #4 reading is odd.. I'd say blown ringlands/rings too.

how much boost were you running when it gave up the ghost?

[WDRacing]

Wow, I've never seen a 0 before. There's always some compression. You had the head off and didn't notice any damage? Were the old plugs completely eroded at the ground strap? Are you sure a valve isn't stuck open?

WD

[fabio420]

12 psi, and had just left the dyno. The a/f was at 11.7, but the safc had the low throttle set at 30% and In third gear I hit 12 psi at 17% throttle( so no correction). Plus the timing might have been off(not at 15 or so)

[fabio420]

If my cams are TDC on the first cylined and so is the block, then shouldn't all the other allign accordingly? If that's the case, then what would hold the valves open?

[Import_Ant]

if one of the valves is bent it could be leaking...

[fabio420]

When I turn the engine over, I thing i hear a shhhhhhhh coming from the head near the 4th cylinder. BTW does anyone know what kind of clearance the shims are supposed to have when the lobes are up. I'm trying to see if I have a shim issue.

[WDRacing]

Both my low and high throttle maps have correction mapping the same on boost. Since I'm almost always on boost at the same given RPM. Better to have bad fuel eco then a blown motor.

[fabio420]

So what's my prblem?Valves open or rings? I can't reason the 0 compression

[Jookmasta]

my vote was for the valve stuck open when we talked. bump for more exposure.

[:: orion ::]

Like I said here:

zerothread?id=124988

I'll bet it's ringlands...really dead pistons will show no compression.

- Brian

[WDRacing]

I just figured he would have noticed some damage when he had the head off Bri. Like the plugs being all ****ed up...lol.

[Structure240sx]

he said there was oil on the plugs

you cant see cracked ring lands until you take the piston out of the cylinder, unless the piston is cracked in half

[:: orion ::]

That was my experience as well...I pulled my head expecting a dead HG, and saw nothing wrong with the piston.

When the HG was obviosly good, we dropped the pan an removed the rod/piston in #4...the broken part was still in place between the rings, and compression was ~40psi.

I have seen 0 from a "more dead" piston than mine...similar breakage, just worse (and broke the ring in one spot, too).

- Brian

[WDRacing]

When I blew all my motors due to detonation I had sparkplug chunks welded to the piston. Thats what I meant. I know you can't see the ring land with the piston in Tony...Don't get all swoll on me *****.