cn_mckinney

VG30E, 156k miles, she doesn't burn a drop of oil. Oil always changed every three thousand miles. But I think she's knocking.

When taking off from a standstill, I hear a knocking noise. I only hear it about half way through 1st gear. Not sure if the noise stops after that or if road noise drowns it out. I think this started last fall. My dad said it was probably an accessory or something. I thought nothing more about it until the other day. I got my dad to listen to it again and he said to check the crankshaft pulley to see if it was loose, nope it wasn't. This morning I took it to a mechanic that lives on my road to let him hear it. The best way to duplicate the noise is to put the tranny in gear and rev the motor to 900-1200 rpm against the brakes. It won't make the noise in neatral. Its very faint like no one would notice it without being asked to listen for it. The mechanic said it sounded like the main bearings to him. Its very faint and its been doing this for maybe 10,000 miles; can't hear it with the radio or even just the air on.

I don't beleive its the exhuast manifold studs(again), those made a tick, tick, tick noise, this is a rattle like nock-no-nock-nock-pop-nock

Anyone experienced this? I'm not driving the car for now.

Thanks for any info at all,
Nolan

Czar

In my opinion it isn't your lower end. Crank main bearings rarely go unless there was an interupted oil supply and the other thing that would knock is a rod bearing. I lost an engine to a rod knock, but it would not knock until 2500 no load and it wouldn't knock under load. Check your oil when you change it next. How dirty is it? is there metal particles coming out? If you think it may be a rod bearing, try this. Have somebody rev the motor to duplicate the noise, and one at a time (Careful you may get shocked unless you insulate yourself) remove the spark plug wires one cylinder at a time and see if or which one will cause the knocking to stop. Rev it up to 5000 and see if you can duplicate your knock anywhere (no load). If you can't hear a knock or engine abnormality then chances are it is something else. It sounds from your post that it is minor and I would contiinue to drive it unless it gets worse if you have driven it for months like this. Watch your oil condition and consumption..... good luck.....

Ryan93SE

iTrader: (1)

i hope thats not the situation your in....

Agamemnon

Hi!

Sorry to resurrect this old and long-dead thread, but my 92 Maxima SE (VE) had the same noise. Just happened like yesterday. Only when I accelerate from stop/very low speed in 1st or 2nd gear, and only at lower RPM (under 3000 or so). It's different than the VTC noise. My VTC is making noise too, but the VTC noise sounded just like a diesel engine and I had to strain to hear it from the inside (truthfully I don't mind that at all, it just adds character! ) THis other noise is different. It's like a rapid knocking. Best way to describe it is like a fan blade hitting something, like when you stick a paper or something into a fan as it was turning. It's not that loud from the inside, but louder than the VTC noise. I'm going to take it back to my mechanic soon, but it would be great if I have some idea of what might be the cause. BTW I put 92 Octane gas on mine, though I suspect the car had 87 octane previously when I got it. I put the gas with about 1/4 tank of the old gas left. Could this 'blend' be low octane enough to cause knocking? It doesn't sound like the typical engine knocking (detonation) either, which is more like rapid "tock, tock, tock..." noise. Though I've never heard a Maxima engine knocking. My old one (VG engine) never knocked!

BTW, the fact that I'm ressurecting this old thread proves that I did a search first!

male

If you get stumped, try adding a thickener to the motor oil. If it quiets down, you probably have a rod or main bearing crapping out. This will only work if it is a slight rod knock. Also, if it continues, not changing with the added viscosity, get the engine nice and hot and drain that stuff out, and continue troubleshooting.