Odd noise(no ur typical timing chain or guide noise) look

[silpena]

specs:1993 240sx, dohc120,000 milesautocomplaint: noise at start up then goes awaywhen:started last year after oil change, car had around 90k.

hey guys i've been having this odd noise on my engine. Its like a buzzing/kinda marble in tin can noise(like timing chain and guide noise but different) It only comes on during cold start up after about 5-6 seconds then become noticeable and then dies down as my car warms up but still there. The noise will go away after 10 goo minutes of freeway/highway driving or some mild pulls. It will come back on if i leave my car for awhile..like 25-40 mins on summers and like 10 min on winter days. I've tried pin pointing it. I think it could my clutch fan because it sounds like its coming there so i got one for 9 dollar and should be at my house soon. NOt to bad, of a price. I just bought a stethoscope to pin point my noise and it comes out that its louder when i put it against my oil filter... idk why. Its odd becuase the noise started one day after an oil change. DO u think its my oil pump or pick up? another thing i have a slight dent on my oil pan. Could that be it. I think i have good oil pressure. I open the oil cap and i'm getting good mountain and some spitting to the cams so i know there is good pressure..but why the noise in the oil filter and kinda but not alot on the oil pan?? i'm just paranoid my pump is dying or something and by bearings are gonna take a dump sooner or later. Any help?? oo and sorry about the long post.

[Vegascorbin]

Far from expert but I think your oil pump idea is a good one. Can't say about the DOHC but I wouldn't think the oil pump is that hard to change and not overly pricy.

I also would recoment you add an after market oil pressure gauge so that you KNOW if you have enough pressure.

[silpena]

thast my next thing to do. I'm looking into getting one soon just to check. I just don't under why it would go out so quick and early. I change my oil regularly, properly warm up my car every morning or when cold(well excessively), i don't beat on my car. MY also guess is i used to use fram and i've hard the card board in them can get come out and clogg oil pathways. Do you think maybe its sorta clogged near the filter or inside somewhere. I can't take off my oil pan. I tried once and i gave up. My hands are too damn big. I had a mechanic do it just to take out a bolt i dropped when putting a new head gasket. HE said everything looked great and there was nothing in the strainer or near lower timing gear and near the pump so i was stumped. I would think at at least 35 k with this problem my bearings would crap out and give me a rod knock or something.

[480sx]

The fact that you could hear it through the oil filter, in conjunction with this problem starting after an oil change is bad news.

Leads me to think that its something in or around your pump. Get under the car and use the stethoscope against the bottom part of the lower timing chain cover near the crank pulley and see what you get.

Thing is, if you'v driven it for 35k already like that its most likely not going to suddenly blow up on you. I would just say drive it till it dies, then swap in another ka.

[silpena]

i did that today and i''m having hard time isolating the noise. Its very clear in the oil filter, kinda in teh oil pan but after it warms up its not that loud but close i get to the block it gets louder. I might just ride it out till dies if i keep it at this way. I get hella pissed and paranoid when other ppl drive my car and don;t warm it up. last thing i need is a rebuild but first i will test the oil pressure and if its ok then i'm stumped.

[silpena]

i also forgot to mention the noise is only at low rpms when i give it slight gas maybe 1000-2000 it goes away and i heard oil gushing and pressure through the filter. SO it goes away when i give it gas. I think a bad oil pump would limit pressure at all times?