No compression...need help please!11!1!! - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

turbo98 · 09-24-2008, 02:43 PM

Ok, ran the car pretty hard last night, after a race I decided to coast from 120 so I put the car in neutral and it dies, won't start back up...got it towed, pulled the plugs and cylinder 1 spark plug prong was smashed onto the electrode, not melted, smashed. Next, I decided to do a compression test and I have zero compression in all cylinders. The rest had no problems with spark plugs. I'm think maybe bent valve(s)....someone please chime in!

Car: 1997 240sx KA-T
Motor: supertech pistons, eagle rods, cometic gaskets, arp studs...tested the compression the week before, ran 160 across the board...

*fliprayzin240sx* · 09-24-2008, 03:35 PM

Hmm...how is it even possible to get no compression in all 4 cylinders? You sure you're gauge isnt fucked up?

japslapsilvia · 09-24-2008, 03:40 PM

+1 on the fucked up gauge

did u have ur t/b open when you did the test?

turbo98 · 09-24-2008, 03:44 PM

yeah sure did...no doubt at all. I'm leaning towards jumped timing, that would explain no compression in all cylinders. Exhaust cam could be out of time just enought to be open and let the compression out...

neilsan · 09-24-2008, 03:59 PM

That wouldnt explain why your plug got smushed, though.

If the motor is still interference when using dished / low compression pistons, then if you jumped a tooth you might have munched some valves. A piece of valve bouncing around would explain the damaged spark plug.

When rebuilding the motor, did you use new OEM parts for the timing chain set? like 5 years ago I rebuilt my first KA with an InnerFireGear timing kit, aka TOPLINE, from ebay. I some how didnt notice when installing it but the lower tension side arm wasn't machined right and was being sandwiched against the block, unable to pivot at the bottom like it's supposed to. The excessive chain slack destroyed the opposite lower guide, and subsequently almost took my motor with it.

turbo98 · 09-25-2008, 08:18 AM

The motor was built before I got it...so I have no idea. I think I'm just gonna go ahead and pull the head off and see what's up and hope it's just valves!

09-24-2008, 02:43 PM	#1
turbo98 Zilvia Member Join Date: Feb 2006 Location: Mobile, Alabama Posts: 292 Trader Rating: (1) Feedback Score: 1 reviews	No compression...need help please!11!1!! Ok, ran the car pretty hard last night, after a race I decided to coast from 120 so I put the car in neutral and it dies, won't start back up...got it towed, pulled the plugs and cylinder 1 spark plug prong was smashed onto the electrode, not melted, smashed. Next, I decided to do a compression test and I have zero compression in all cylinders. The rest had no problems with spark plugs. I'm think maybe bent valve(s)....someone please chime in! Car: 1997 240sx KA-T Motor: supertech pistons, eagle rods, cometic gaskets, arp studs...tested the compression the week before, ran 160 across the board...

09-24-2008, 03:35 PM	#2
fliprayzin240sx Man w/ CTSV & a Car Seat Join Date: Aug 2002 Location: Tampa Posts: 17,998 Trader Rating: (19) Rides Gallery: fliprayzin240sx Feedback Score: 19 reviews	Hmm...how is it even possible to get no compression in all 4 cylinders? You sure you're gauge isnt fucked up? __________________ If you think Zilvia has too many assholes... CLICK HERE!!!

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09-24-2008, 03:44 PM	#4
turbo98 Zilvia Member Join Date: Feb 2006 Location: Mobile, Alabama Posts: 292 Trader Rating: (1) Feedback Score: 1 reviews	yeah sure did...no doubt at all. I'm leaning towards jumped timing, that would explain no compression in all cylinders. Exhaust cam could be out of time just enought to be open and let the compression out...

09-24-2008, 03:59 PM	#5
neilsan Zilvia Junkie Join Date: Sep 2004 Location: east coast Age: 40 Posts: 333 Trader Rating: (0) Feedback Score: 0 reviews	That wouldnt explain why your plug got smushed, though. If the motor is still interference when using dished / low compression pistons, then if you jumped a tooth you might have munched some valves. A piece of valve bouncing around would explain the damaged spark plug. When rebuilding the motor, did you use new OEM parts for the timing chain set? like 5 years ago I rebuilt my first KA with an InnerFireGear timing kit, aka TOPLINE, from ebay. I some how didnt notice when installing it but the lower tension side arm wasn't machined right and was being sandwiched against the block, unable to pivot at the bottom like it's supposed to. The excessive chain slack destroyed the opposite lower guide, and subsequently almost took my motor with it.

09-25-2008, 08:18 AM	#6
turbo98 Zilvia Member Join Date: Feb 2006 Location: Mobile, Alabama Posts: 292 Trader Rating: (1) Feedback Score: 1 reviews	The motor was built before I got it...so I have no idea. I think I'm just gonna go ahead and pull the head off and see what's up and hope it's just valves!