So I've tested the compression and had values as low as 10psi. Not sure what factory numbers are but I know this is definitely too low anyway.

Unless I find a well priced engine soon I will go ahead and changed the head gasket, straighten and plane the heads if needed and so on. Before I can see how far the damage is gone I need to remove the heads.

Since searching I haven't found a definitive write up for head gasket replacement. It all appears straight forward but my main concern is with the timing chain, setting the timing correct and working with those moving exhaust cam sprockets. If anyone can provide advice or any tips I should know before starting that would be great.

Thanks again
Brad

 

Slow down.

First, what makes you think this is a HG problem? Low compression is due to bad piston rings, and yes, 10psi is waaaaay too low.

Also, HG on the VQ are extremely involved and should only be attempted if you are well experienced and/or familiar with the process. There is a thread here somewhere with a decent writeup.

 

Jeez. At 10psi your gas MPG must be great. Unfortunately your oil MPQ must be tragic since that is what you are using for fuel.

 

I figured it is a headgasket problem because it over heated, the compression is bad and the coolant system is pressurizing.

I was actually driving the car one day when it overheated and seized/stalled out.
After it cooled off it would crank fine but wouldn't start and the coolant system was being pressurized whilst cranking the engine over.....

 

The timing chain is very easy to do. I don't think it would be a wise decision to start any major repair on a modern engine without some sort of technical guide. Even if you know what you are doing, you still need to reference torque values and sequence. In short, get yourself a manual of some sort. ie chilton or haynes.

 

here is a link to the fsm http://www.nicoclub.com/FSM/350Z/

 

Thanks, I managed to find one for the 2004 g35 Coupe.
I just need to find the part for the timing and head removal

 

Does anyone know how much I'd be looking at to have both cylinder heads planed?
How much would it cost to check for cracks?

 

It would cost more than just replacing the engine with a nice low-mileage junker/replacement.

 

salvage yards charge around 1200 for good engines and the oem gasket kit goes for less than $400. So there is plenty of room between the two. Plus you don't know what you are getting with a used engine.

the fsm says the cylinder heads aren't machinable so if there is any warping, the head is likely no good anyway. I would invest in a good straight edge and check them yourself. As far as cracks, you should do a cylinder leak test prior to removing the heads and take note of any problems founds. Inspect on removal and try to pinpoint the cause. If you suspect a crack, take it to a machine shop.

 

I've actually found an engine in a running car for around $500.
The engine is still in a G35 so I can hear it running and I remove it myself.

The leak down test will show air escaping into the coolant system. I am sure of this as when the engine is cranked by the starter, I can feel the upper rad hose pulsing and getting harder. Then, when I open the rad cover water shoots out......all that from just cranking the engine over....