TwinTurbo.NET: Nissan 300ZX forum - No start issue, update and a thank you
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Subject No start issue, update and a thank you
     
Posted by BannonZ on June 05, 2019 at 10:17 AM
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Message Hey guys,

Just wanted to shoot out a quick post with an update for those who have helped me in depth with this issue for the last few months. Thank you especially to Bernie Bilski for allowing me to pick his brain and his help/time.

Contrary to a good warm test of the compression, we took off the valve covers with the engine out and found the passenger side had a 100% leakdown and held about 40 psi compression when cold. Drivers side had about 80. Not Good. What we found was that one of the valves was pushing the lifter up and pushing the camshaft brackets out causing the cam to gap and allow air into the intake side when the exhaust was closed. We pressed the brackets down to close the gap and had 12-130 psi compression across the board. Lower end is solid, 0% leakdown when we closed that gap. Have a new (used) set of heads at the machine shop getting cleaned and a valve job done. The set had about 10 miles on it from a buddies blown up lower end 91TT. My techs and I are relatively confident this should fix it.

Question is: what caused it? Part of me wants to believe that it has something to do with the bulletin from 92 about the valve size and mushrooming the inside of the heads leading to poor compression. The other part of me thinks that the machine shop that did the valve job of the car 16-17000 miles and 7 years ago poorly and cleared out the valve input holes too much. Weirdest part is that when the car did start, it idled poorly for about 1 minute and then ran like a top.

Sucks, but to be honest I am happy to have finally (hopefully) found a resolution to this issue. The bright side is that I have replaced every single bolt on component on the vehicle to try and compensate for the issue.

     
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