Turbo_Tay

Cold someone who is knowledgable is rebuilding a vq35de answer or help me diagnose where I went wrong. So I rebuilt my 350z new rods Pistons bearing head studs head gasket ect. And after putting it all back together I found that it won't turn over. Before doing the timing I was able to spin the crank and hear each piston push air out the hole for the spark plugs. After doing the timing I was unable to spin it over. I put it in the car to see if the starter could spin it over. I get a single click and nothing moves when I turn the key. I later realized I over tightened the cam bearing caps to 20lb pounds in stead of the 105in pounds they are supposed to be at. Is it possible that I squashed the bearings and therefore the clearance is no longer there which is causing the cams to lock up? If anyone could give me some advice or knowledge that would be very helpful!

GreyZ

iTrader: (2)

I haven't done a vq35de specifically, but overtorqueing bearing caps will most definitely lock stuff up. That's more than double the torque required.

CK_32

iTrader: (1)

That would probably be a start.


Torque them properly and see if that helps. Also hope there isn't tolerance stacking and you lubed and oiled all necessary parts properly during the install.

Conway_160

iTrader: (1)

I would pull your timing chain and see if you can move your crank back and forth. Once thats done remove your cams see if they are messed up. Then reinstall then and and torque them correctly set your timing and see if you can spin it.

Turbo_Tay

I have taken the timing chain off and was able to spin the crank freely. I also torqued the cam bearing caps to the proper spec however it still will not turn over. I called a machine shop to see if they could check/fix the tolerance between the cam and caps and he suggested I am better off getting new heads and cam. I found a set of used oem heads with cams for 500$. Anymore suggestions or help would be greatly appreciated. Thank you everyone definitely very helpful!

Turbo_Tay

I'm curious what you all would suggest. Spend the money on a set of new heads or should I attempt to have them machines to work again.

Conway_160

iTrader: (1)

I would see if you can move each cam by themselves with a crescent wrench. Then see if you can do each bank with their timing chains on. That will determine what Is going wrong. I'm betting you have the timing off and a valve is hitting the piston.

Turbo_Tay

I lined up all the tick marks on my crank cams and chains. I will take pictures of where I have the marks tomorrow and post them. Thanks for all the help!

Conway_160

iTrader: (1)

Undo the timing to find out what's binding up. It's the only way to figure out whats going on.

bealljk

iTrader: (13)

I agree with conway...take your primary and secondary timing chains off and rotate each independent of system as a whole.

But before you do that take 30minutes and inspect the valves ... make sure there is nothing jammed or mis-aligned in your valve seats/springs/retainers...


If it was me I wouldnt buy new heads/cams - that's the 'throw parts/money at it' approach and it may work but you'll replace alot more...and find a different machinist...

CK_32

iTrader: (1)

I personally would just figure out wtf is the problem and fix it.


But my Z is a project back up, to the back up car. So I have time. If your tight on time sure go grab the cam. But I would just figure it out and fill my excuse to tear it apart and get wrenching if you got the time.


Do you have any of the old OEM parts you replaced? Process of elimination rebuild it back to OEM stock and add one at a time and see whats snagging you. Rather than play the guessing money game and buy parts that might not even fix it.