What could make this knocking noise

[Mayday0017]

Ok this will prob be semi long but please read and help I'm looking for answers and can't find any.

I bought a 1995 240sx that has been sitting for a year. I have replaced, Radiator, fuel pump, fuel lines, fuel filter, plugs, wires, distributor cap, rotar, battery, all belts, front main seal, headgasket, had the head worked over by a machine shop, Replaced oil pan gasket.


I drove the car about 2 hours to houston the day before I did any of the work below. With out any problems other then the oil leak I was driving there to fix. Also had been driving the car around town just for fun at night and stuff and to work afew times.


The last two things I have done was I replaced the oil pan gasket, and the car was still leaking oil so I then realized it wasn't the front of the oil pan it was the Front Main seal. So I replaced it as well even drove the car to the store to get the seal. After replacing it, no more oil leak. I drove the car to the car wash let it idle the whole time no problems no leaks noises or anything drove it back with no problems car ran perfect, had the car in the garage idleing while I vacumed it out, still nothing. Then the car died all the sudden, so I told my friend to crank it back up and it started right up idled just fine. Then I went to show my dad how smooth then engine was running now since he had last seen the car and I reved it a little and at 2k you hear a loud knocking noise and anything past 2k. What could be causing this, I don't think it is a bent rod cause you don't hear anything at idle. I also don't see a rod getting bent at idle. It sounds to loud to be a valve and I don't see how a valve could be having problems now all of the sudden. Also the car hasn't ran hot any. Does anyone have any suggestions thoughts or anythign on any of this, any input would be greatly appricated

[Autofreefindersguy]

I wonder how your oil pressure is?
Maybe when you rev it, its not getting the oil pressure it should and your hearing noise that you normally shouldn't?
Have you checked your oil level as well?
(Just a guess without hearing it myself)

[Mayday0017]

I dont' know what the oil pressure is or how to check it exactly (would be nice if nissan would of takent the time to put a gauge in) And yes plenty of oil since I was checking oil leaks it's full of nice new oil.

[Mayday0017]

bump

[R.W.240]

Prolly Ran Low on oil on the way to get it fixed and spun a rod bearing

[sidewayzdrivin]

yeah check your oil level. oh and is it a clanking sound like something sounds loose inside???? and does it only happen when you rev it up a little ??? oh and check to see if you can hear it at idle by putting one end of a cresent wrench to the valve cover and the other to your ear. if you can hear it(it might be faint) and your oil level was low the i would assume it was your timing chain guide thast broke free. the tension of your timing chain is controled by your oil press/level when it gets to low the chain will rub on the guides when it gets really low it will break them(just plastic) but it no big deal if thats the prob just pull off your vavle cover and clean out your timing chain area you dont have to replace it but some people think it is nessesary(but its not). if its not that then maybe something else is loose maybe near your exhaust like one of the heat sheilds. keep me posted on what you find

[Mayday0017]

The only time the oil has been low in the car it showed 1/2 full when I got to houston the day before I worked on the car. At that point there were no noises. I dropped the oil pan replaced the gasket, then filled the car full of nice new oil. The car was full of oil when the problem occured. I'm curious could I have over torqued the Hermonic balencer when I changed the Main seal later on that day? The noise didn't start until about 1 hour after the engine running. Also the engine did die and would not start while we were trying to find the knocking noise, after the car cooled down over night it started right back up but still knocks. Anymore ideas?

[Mayday0017]

bump

[nissanfanatic]

Check timing. Sounds like it spun a bearing if it died and then started knocking though. Good luck.

[monooxide]

Man...that sucks I have a problem on the Exhaust "Flanges" that cover the exhaust near the Manifold it rattles at like 2000-2500 depending on gear but there should be a WAY big difference in sound...I say if you have a second car just start taking her apart...make sure you have a Manual for it and not the one that came with it so you know the Ft-Lbage" for all the bolts on the actual engine