smokey grey 37

So I bought a used engine took to mechanic and he tested the engine by spinning the crank.

Crank spun fine no lock ups or nothing but the intake valves never opened...

I've been told that those won't open unless the vvel is being powered.

Mechanic is saying the engine is no good since the valves aren't opening/closing and that vvel has nothing to do with it.

We didn't take off the exhaust manifold to check and see if those are moving....

Is the mechanic correct in assuming the engine is toast?

Or was me playing detective on Google correct about intake valves not opening due to vvel?

SkysG37

I dId a compression check on a used engine.
Only powered the starter. NOTHING ELSE,
She was 130 across the board.
The intake valves indeed move.
Just at the lowest, default, lift.
Your next step is to pull the valve covers and watch the cams

BULL

Valves are controlled by the VVEL mechanism. Without power to the VVEL motors the Valves will be at minimum lift/closed.

It catches a few people by surprise. For $50 I can send you a video of my engine stand that runs with and without the intake manifold to show that valves do not open when motors are not powered.

Apologies if I come spicy but if your mechanic does not trust the forum advice he should not have any issues forking $50 to clear his confusion. All that confusion is time wasted and car with no engine.

SkysG37

From a Maxima forum...
"TurboS13Hatch , 03-22-2007 12:19 PMSenior MemberWell, I got some scoop on the valvetrain design.. apparently, the engine still has 4 camshafts.. but, they're not designed with lift/duration in mind.. in other words.. the camshaft is designed just as another "chain in the link" so to speak.. Between the cam lobe and the lifter bucket.. there's a jackshaft, and 2 wiper pads.. the jackshaft has a progressive profile cut onto it for each cylinder.. On one end, the profile starts at 1mm lift and something like 50-60 degrees of duration.. On the big end, the shaft has something like 11mm lift and 290-300 degrees of duration.. the shaft turns approximately 270 degrees back and forth.. So, if you set the jack shaft to the small end, at 0 degrees, you get 1mm lift and 50-60 degrees of duration.. this would be the engine at idle.. if you want to increase engine speed/power, you turn the jackshaft (operates like a worm gear) using an electric motor on the front timing cover.. as the shaft spins towards 270 degrees, the valve lift and duration increases.. eventually getting to the full 11mm lift and around 290-300 degrees of duration. The cam is still there to tell the valve to open.. but, the jackshaft is what tells it how much to open and for how long.. This eliminates the need for a throttle plate, because at 1mm lift and very little duration.. the engine barely runs.. which is interpreted as "idle".. Atomization on cold start is dramatically improved as well.. because the velocity of the fuel/air entering the cylinder goes way up as it passes through the 1mm opening between the valve/valve seat. By increasing the velocity and "squishing" the fuel.. you get much better atomization, and less unburned fuel on cold start. There is still a throttle plate in the system, but, it's only used for emissions and a failsafe, in case something fails in the VVEL system.

Travis"

https://maxima.org/forums/all-motor/...iscussion.html

BULL

the vhr uses a very similar tactic however instead of duration like the Maximus the vhr is doing so in adjustable and variable lift