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vg30dett compression testing procedure?


Mack

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I am putting a Z32 back on the road this summer.  The engine that is in it has a rod knock.  that one is shot.  I have an engine that I pullled out of car that last ran 5 years ago that I unfortunately put into a wall during a track day.  I also have another engine that was pulled from a t-boned red light runner about 6 years ago.  Obviously, neither one of these engines have run in quite a while.  

 

 

I tested the walled car, all spark plugs out, one cylinder at a time with a battery and the starter still hoooked up to the trans.  I got anywhere from 45psi to about 90psi except for one cylinder at about 150psi.  I checked and all timing marks line up, so I know it's not that. 

 

I checked the T-boned motor the same way as the walled car, and every cylinder is about 45 to 60 across the board. 

 

I KNOW for a fact the walled car ran and drove, and boosted quite well.  The other one, I bought on the guys word.  

 

So, is it possible that both these motors are Fizz-ucked? or am I dealing with hydraulic lifter bleed down? (as both have been sitting for at least 5 years)  does something need to be done with the VTC?  

 

the tests were done with just the positive and negative hooked up to the starter with a jumper button thing.  No fuel, no spark no ECU.  

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Did you try measuring them wet with a squirt of oil into the cylinders?  Turbo motors are supposed to be lower compression due to the turbos adding air, but yours sounds low to me.  What does the manual say the process is?  You have downloaded the manual right?

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Yeah, oil brought one of the engines up some, but the other was still low. I made a leak down tester and I'm certain the issue is valves now. Burnt valves, to be exact. Cylinder 1 is about at 95% sealed and the next highest is around 45%.

 

I spun the engine with a ratchet on the crank pulley with the tester in the plug hole and air never stopped coming out of the exhaust on most cylinders, some the intake too. Time for a valve job.

 

Can you post a link to the manual?

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