Monkies

It appears that when I did my timing belt, I failed to bolt the driver side cam gear completely. I found this out during highway cruise at 60mph when the engine lost power and I heard engine knocking (pistons and valves).

I caught onto it pretty quickly and only lasted maybe 2 seconds. I plan on getting an inspection camera and taking a look at the valves through the intake, however, the driver cam gear has ripped the keyway off on the cam roller, and both need to be replaced.

This is an N/A to Turbo swap with only 133k on it. My main questions is would an inspection camera be able to identify if the valves have damage, and if it is possible to replace the cam roller without pulling the heads.

If I don't have to pull the heads then I don't want to, however it would be the third time I have done it to a Zcar, just the first time to deal with turbo exhaust. (I haven't had good luck with exhaust bolts.....) If I pull the heads I will most likely try to convince myself to modify the turbo and get that done for future proofing my mods.

Pics of the carnage included....


Thanks in advance!
-Mark

Numbnuts

First thing I would check is to see if the 3.0 is a non-interfering motor. Hoping the noise you heard was just the cam gear coming off & bouncing around & not the valves on the pistons.

Numbnuts

Everything Ive read so far on those motors point to it being an interference motor. Im sure others will verify this, but looks like you are going to need to pull it apart & rebuild the heads due to the damage.

NismoPick

Your main question: Yes, if your camera has a light, you'll easily be able to tell if there is damage or not.
Replacing cam question: time to open the FSM: Z31 Factory Service Manuals

Monkies

Awesome, thanks for the info. Assuming there is damage to the valves, would I be better off swapping both cylinder heads from a pair at a salvage yard? They would find their way to a machine shop first to get worked on before install.

Thanks!
-Mark

86tcoupe

There is damage to the valves 99% sure
Best to tear down and see just what happened. Depending on the rpms at the time usually tells the best route to repair

Monkies

Definitely had some valve damage. Cylinder walls appear to be ok. Only one valve broke, but it did a number to the piston head (it doesn't look like it got very deep). We used a dremel to smooth out the gouges on the top of the piston and turned the engine over a few times to look for other damage.

Have new heads on now and should finish up the rest of it this weekend. How concerned should I be about that piston? Pictures are included.