300zx smoked out

  • #1

    300zx smoked out

    Alright been scannin the site for a while and finally had a reason to post.I picked up a 87 300zx about 3 weeks ago got it for 350 so wasnt complaining about much.The thing is the car has been sitting for 2 years, reason being the last owner had snapped the timing belt leaving a stop sign.I was told that they replaced the belt and distributor and checked to make sure the valves still freely moved up and down i dont really know what this accomplished but o well.They tried starting it again but it wouldnt start and they burned the starter trying.So now that your up to speed here is where im at now.I was pretty sure getting into this that i would have to replace the valves and seals but thought i might as well try starting it to see whats goin on.I did a basic tuneup replaced all the plugs,wires,egr,oil,oil filter,coolant,and air filter.Also picked up a new starter.Since the car had been sitting i poured some oil down the cylinders to lube them up.Also i fixed the timing since they were off a tooth.After playing with the distributor for a bit the car fired up.This is where my problem starts to keep the car running i have to keep the throttle wide open and it bounces between 2 and 3 grand on the tach.Also the car is smoking extremely bad like when u spray seafoam in the motor except this smoke never ends.I also noticed some smoke from the drivers side of the motor figured this may just be a leak.Also the water temp gauge is not working but all other gauges are this might just be a faulty sensor.So pretty much im asking from your guys experience is this for sure the valves or something else?All my experience is in hondas new to nissans any help much appreciated.And sorry for the long column but wanted to make sher all the info was here.
  • #2
    To test a Honda for bent valves, you do a compression test.
    To test a Nissan for bent valves, you do a compression test.
  • #3
    I hate to be the one to tell you, but you probably are going to have to pull the heads to see what's going on with the valves and pistons. Bent valves and perforated pistons are common after a broken timing belt.



    1988 300ZX Turbo, Shiro Special #760
    1988 300ZX Turbo Automatic (wife's car)
    1991 Hard-body 2WD

    http://zccw.org/zccw/?page_id=1215
  • #4
    Careless wrote: To test a Honda for bent valves, you do a compression test.
    To test a Nissan for bent valves, you do a compression test.
    Yea haha figured that just waiting on a friend to bring his over tomorrow just wondered if there might be another cause
  • #5
    reddzx wrote: I hate to be the one to tell you, but you probably are going to have to pull the heads to see what's going on with the valves and pistons. Bent valves and perforated pistons are common after a broken timing belt.
    Dam im hoping the pistons are still fine do snapped belts in these usually leave valve indents in the pistons?And yea lookin forward to taking these heads off somethin new for a change and depending on how bad things are im probally gonna just use these heads for messin around probally just practice porting.So after tomorrows compression reads ill probally be lookin for heads anyone in california sellin some hahaha.
  • #6
    z31kidd wrote: Dam im hoping the pistons are still fine do snapped belts in these usually leave valve indents in the pistons?And yea lookin forward to taking these heads off somethin new for a change and depending on how bad things are im probally gonna just use these heads for messin around probally just practice porting.So after tomorrows compression reads ill probally be lookin for heads anyone in california sellin some hahaha.
    I've had standard valves destroy forged pistons - when two pieces of metal move in opposite directions at a high velocity, and then touch, bad shit happens. As you've scanned the site for a while you know we really urge people to do the job ASAP if they don't know when it was done last, because it gets expensive if it breaks.

    BTW, the sensor for the water temp gauge is like $5 at Autozone.
    Feedback- viewtopic.php?f=18&t=19840
  • #7
    Any basic knowledge about a reciprocating engine should have told you to do a compression test, or even more accurate a cylinder leak down test.
    - VG30DET (HE341) 86 300ZX - 1982 280ZX Turbo - Headered NA 1986 300ZX 2+2 - 2000 Xterra -