Hi guys,

I recently picked up an 07, that needed some TLC, I did the radiator, drive belt, brakes, oil, brake bleed, coolant flush, O2 sensor myself.

the previous owner claims the timing chain and tensioner were replaced and the owner before him put a lightweight fly wheel in. He said something about possible pilot bearing as well.

anyways, since I got the car there has been this odd grinding noise that lasts a second during the startup then disappears. I only got it to go away once after it was a warmer winter day and the engine was warm. I put Penzzoil 5W-30 in and it didn’t change the sound. I’m brand new to driving stick and when I start the car I push the clutch and brake in while the handbrake is engaged if that helps??

I attached the video below.

I’m not what is causing it?

 

Is it the starter not disengaging right away?

 

I really can't hear the grinding noise in the video. I hear the starter engage and then all exhaust once she fires.

Note: It's common to hear some chain rattle on higher mileage Zs during cold start. This is from slack in the timing chain either due to worn guides, chain wear, or tensioners needing a moment to pump up with oil pressure. What's strange is that those components were said to have been replaced. My guess, is that what you're hearing is cold start timing chain rattle. Just based on this only happening when the engine is cold. But you can test this theory using "clear flood" mode on a cold start to build oil pressure before starting.

Hold the clutch and gas pedal to the floor while turning the key to start/run. This will deactivate your fuel injectors and allow the starter to turn the engine over and build oil pressure. NOTE: You must keep both pedals depressed while holding the key in the start/run position (cranking). I like to prime/crank the engine for about 10 seconds before starting it. Simply take your foot off the gas pedal to start the engine normally and listen for that grinding noise.

Good Luck!
-Icer

 

Sorry, I couldn't play your video, but my guess is that it's the idler shaft in you gearbox and the gears are rattling because lightweight flywheels generally don't have a vibration damper or springs, as does the OEM flywheel, to smooth out the output from the engine. The rotational acceleration/deceleration that come from the cylinders firing and slowing down in the power and compression cycles, those vibrations make their way to the gearbox and this causes the gears to slap back and forth against one another. You can test this by depressing the clutch while it's making that noise. If the noise changes, then this is it. This is perfectly normal, and the heavy-duty manual gearbox in the Z is more than capable of handling it, well, up to a point. So you can either live with the noise, or switch back to an OEM flywheel.

Clutch and brake during startup is correct.

5W-30 is correct, but I would switch to synthetic on the next oil change.

 

What frenzee described is a phenomenon known as Torsional Vibration. Typically you won't get this type of noise (gearbox chatter) until you're in gear, low rpm, applying a torque load (throttle) through the gearbox, it usually clears up after going above 1500RPM. But there is a chance you could be getting some initial noise from the transmission input shaft to the countershaft during startup. A lot of Z33 owners also describe a "cement truck" like noise from the bellhousing area while the vehicle is idling in neutral. This is typically caused by a worn throw-out bearing or input shaft bearing. That noise will also change depending on clutch pedal position (pressed vs. released).

On Z33s with 6MT, you don't need to hold the brake pedal to start the engine. You don't even need the vehicle in neutral. You just need to have the clutch pressed in.

I also recommend using synthetic, but I would bump up to a 5W-40 or 0W-40 (I'm personally using Pennzoil Ultra Plat 0W-40 and have been collecting used oil samples and posting results on these forums). If you have signs of oil burning, maybe try some Valvoline "Restore & Protect", there's lots of evidence showing this new product cleans up fouled piston rings, helping to alleviate oil consumption and in some extreme cases even loss of compression. It doesn't work overnight of course, this is something that takes 10 to 15k miles worth of continued use to see the full benefits. It certainly does a fantastic job cleaning up engine internals with heavy varnish and/or sludge build up due to lack of maintenance.

Cheers!
-Icer

 

No, it isn't necessary, but I would highly recommend it on any MT since the Z only has about 3" clearance up front, so you don't run into a parking stop or god forbid into another car, if you're parked on a slope - good habit to learn regardless IMO. I've done it may times and I have no desire to repeat it. Otherwise, everything else in your post, 100% agreed.

 

Yes, I agree. It's very situational, I was just pointing out that "technically" you don't need to hold the brake pedal to start the vehicle. I know many late model cars these days make this a safety requirement for the starter to engage (usually on push-button or smart key vehicles). But, if you're on level ground or a gentle slope, the parking brake should be more than sufficient to hold the vehicle in place during startup. If your parking brake or e-brake is unreliable (easily slips), then it's out of adjustment and needs attention. I always leave my Z with the parking brake engaged. I've grown accustomed to using it over the years and now it's become a force of habit, I always set it, even on my vehicles with ATs. If I'm parking on some insane hill like you find in SF, I take the extra safety steps (turn the wheel + put in gear + parking brake).

To your point, use the brake pedal before releasing the parking brake, especially in the steep hill scenario.

Anyway, I think we've hijacked the thread now.
-Icer

 

so it’s definitely not a chain rattle, I tried clear flood mode and it didn’t help, I actually ran the car for 15 minutes last night after not starting it for 4 days and the startup sounded perfect once it was really warm and idling. I’m not sure if it’s not receiving enough power during the startup after sitting for a couple days or something is drawing too much power during the startup. But once it’s warm for a bit it sounds just fine. The sound is a bit embarrassing though.

 

here is a video closer to the bay, I started the car and let it warm up for 15 minutes at idle a week ago, turned it off then started it and it sounded like a way stronger startup and no weird noise during the crank. The video is with the noise after starting it a couple days ago, no warmup prior. I’m thinking failing starter or something draining some power

 

I listened to the video in your last post. I don't hear any abnormal noises at startup, it sounds healthy to me. If the problem is intermittent, then it could be related to the starter, perhaps the spur gear isn't retracting or disengaging the flywheel properly every time? Other things worth a look would be accessories and pulleys. Check idler pulley bearing, alternator, PS pump, and AC compressor for any signs of worn out bearings. In terms of the engine itself, it sounds good. The only other possibility that comes to my mind is the fact that you have a lightweight flywheel.

Since you have an HR, keep an eye on the oil pressure. The HRs are known for timing case oil gallery gasket failures which can lead to reduced oil pressure/feed to the cylinder heads. If the timing chains/guides were serviced, then there's a good chance that the gallery gaskets were replaced with the updated parts, but without paperwork (parts receipts or shop work order notes) to prove this, you cannot assume the work was done.

Cheers!
-Icer