Gerbil

My worst nightmare has happened! I started my car after swapping all of my spark plugs to fix a misfiring problem and heard a rattling sound. I immediately shut the car down to (hopefully) prevent any damage.

What can I do?! I just got the thing on the road, I can't afford to have this happen!

I'm just freaking out right now! I have no clue what I could have dropped in there or how to get it out.

Please help.

PredatorZ

If there is any chance you have dropped something down a spark plug hole, you were correct in reacting fast, but some damage may be done. Double check, make sure nothing is rattling around in the fan. At some point, you will need to pull the head and see what is in there. best case situation it costs you a few gaskets and time, if you bent a valve or 2 most likely it is localized to one cylinder, so getting the head repaired won't be to expensive, unless you trashed your piston. I hope it is something simple, because you are right, this is every Z owners nightmare (short of totaling your car like I did), good Luck. I would pull some plugs, us a magnetic extension pickup tool and fish around in the cylinders you suspect and see if you can pull it out. Kind of like those arcade games where you pick up a plush toy, trick is you are doing it blind, so be patient.

zxguy1986

Please give Z31 model, year, turbo/na, year, transmission, mileage.

As best you can, describe the rattle sound in detail and where it seems to be coming from. Good info in = good answers out.

Gerbil

It's a 1989 NA2t car running an infiniti m30 ecu. The engine only has about 75k on the clock. It is running an na 5 speed.

I am also at school. I live on campus and am nowhere near home. I wish I could just shake the thing and find out which cylinder it is.

50SEVEN

You could try doing that, just pick the car up and turn it upside down and shake! If you're lucky you'll get it's lunch money too!

Alright, joke aside, as was said before, you're best bet is to take a look in. It's possible that one of the plugs snapped. It's unlikely, but I've seen it happen when people use old plugs or aren't careful with what they are doing. And by, "I've seen it happen" I mean I saw it once.

Gerbil

Unless I find something soon, I may have to sell the car, is anyone interested? I am in Marietta, GA.

Pics of the car are under my profile. If I don't find anything soon, I will post a video of the engine running under this thread.

The chassis has about 200k on it with NO RUST, and a sweet red paint job. It has a history of hating its owners and draining my wallet.

And the engine... well, its explained in the thread.

Just make an offer...

Stay tuned for more news at a later time.

Gerbil

1989 Z31 Engine Rattling:
Well, here's a video of it running, please let me know what you think.

zxguy1986

Not sure. Sounds like not running on all six. But I definitely would not dump the car so fast without having a real Z pro take a look/hear at it first. The magnet tool suggested above isn't that expensive and you could remove the plugs one at a time and check for loose stuff in the cylinders. Looks like the camera guy thinks it's on the driver's side. And nothing inside the cylinder is magnetized so a loose piece will come out without trouble if you have some patience.

The plug hole is small so it would have to be a bolt, nut or small socket head. Or a broken plug piece, like PredatorZ said.

It could also be something simple that doesn't involve a piece banging around inside. Car looks well-maintained and clean!

Don't give up so easy. Find a real Z pro in Marietta and get him over to it. Offer him a small cash bribe, donuts & coffee, and a date with a hot Georgia co-ed. You may be happy with what he says.

Gerbil

Before I made the video, I spent the day with one of those magnet tools in each cylinder and got nothing. My camera guy was going around the engine to see where the noise is loudest, it seems to be coming from the drivers side center cylinder.

With what I know now, I may try and REALLY look into that cylinder.

Thanks.

Gerbil

So I spent all day probing the cylinders of my car and found nothing. An hour ago, I finished, got in my car, and started it.

The noise in the video was still there, but being out of options I gave the car a little gas and the noise disappeared. I left the car running until a few minutes ago. No smoke from the exhaust, no noise (other than the usual valve ticking) and no misfires.

So, is this thing just going to grenade on the highway or am I good?

zxguy1986

Mysterious. How about a blocked oil feed to a valve? Would that produce a knock that disappears when the feed suddenly opens? Anyway, think sticky valve, noise coming from under valve cover.

Get a pro oil change done with a new filter. Correct oil is 10W30? Keep checking the oil level regularly, see how much you're burning or leaking. Keep oil level right, not under or over the dipstick range. If valves are noisy, try one of the oil additives that promises to clean your valves. Mystery, Marvel, stuff like that. I heard they work.

If there is still something down in the cylinder, your problem isn't over. But drive it around town for a while, see what happens. Listen for the knock to return. I think it's a bad idea to think about selling it when it has a repairable problem (it's only a machine needing the right maintenance by a human). The car looks great and owes you more fun than you've gotten so far. The owner before you cared about it the right way, as we see. Hang onto it. It's an amazing creation when you realize that it's a only an assembly of used car parts, some of them really old and really used.

You can join AAA there. For a basic membership you get a bunch of free tows, free or very cheap. It saves major bucks when your car has repeated breakdowns on the road and you haven't located the cause yet - to do the permanent fix. AAA is a must for old car enthusiasts. Saved me thousands over the past 5 or 6 years - and lotsa worry from leaving it wherever it died.

Keep up the good work and keep in touch here.