1991 240sx fastback- in need of help, so a few questions??

[alteredimage240sx]

Hey guys, I don't know if any of you will relate to this story, but I haven't been on in awhile and should probably recount it. Last June, my boyfriend was driving our 240sx when we drove over some garbage left in the road. Ensconced in said garbage was a large rock once we went back to look. Needless to say, large rock + lowered Nissan= BAD. It was a 1/4 mile from our house or so, and immediately after hitting the junk, the car started making noise and the oil light came on. We got it home and jacked her up to find a gigantic dent in the oil pan. Well, we assumed it was the pump not working back then. Tonight we decided to try a few things to see if it we could diagnose anything different. After throwing a charger on her, she started amazingly. The oil light was still on. She drove and ran decently, but had a nasty noise still. We took off the valve cover and my man did some experimenting. He checked for oil on the cams and timing chain, which it had oil on both. When he pressed on the timing chain to check the tension, the noise stopped. She quieted down right away. We're assuming that after 181,000 it will need to be changed obviously, especially since the rock incident. Our question is, is it enough oil, and is it possible to attach an external oil pressure gauge to see if it was just a sensor we damaged? Also, while he was checking the tension on the timing chain, the top gear of the lower chain seemed to have play in it. Is that supposed to have play in it, or did we possibly damage it when we hit the rock from the jar it gave the engine? Could someone help us locate the stock oil pressure sensor? Is it internal or external? Thanks for any help you can give us. I'd rather not have to pull this motor and swap it if it can be saved. I'd also like to get her back on the road as she got 33mpg, and we're driving a truck right now that gets 12, if you know what I mean

[vancouverbc]

I dont know anything about this but I checked the factory service manual. There is an oil pressure switch close to the oil filter. It has wires going to it and it will likely be covered in oil from changing oil. You can check the oil pressure by removing the oil pressure switch and attaching an oil gauge at that point. A noisy timing chain is not usually a cause for concern.

There is an oil strainer and something that picks up the oil from bottom of oil pan so if that is damaged you wont be getting proper oil circulation. the noise might be a worry if you have something loose moving around.

Anyway, there is more detail in online fsm in my signature. The fsm isnt always available for download. you have to keep checking for it to be available.

zer...age=1

[480sx]

The only thing i can think of off the top of my head is that your oil pickup was damaged when that rock came up into the pan. Damaged to the point where its barely picking up oil. Typically the oil light only comes on when there is freakishly low oil pressure, between 0-5 psi.

You could remove your stock oil pressure sending unit and stick an aftermarket gage in there and see what the deal is. Or you could pull the oil pan and see whats going on with your oil pickup. Did the rock do the most of the damage directly in the middle of the part that hangs down, about 5 inchs away from the front of the pan? Thats where your oil pickup sits.

I cant see how the oil sending unit could have gotten damaged by the rock but thats an easy thing to check, i think you can see it by jacking up your car its right next to the oil filter. Its a white(well black cuz its covered in oil) cylindrical thing with a plug coming out of the back. I guess check and see if the plug is still attached, or if the sensor itself has physical damage to it.

To be honest this is a pretty freak accident, the oil pan on the KA is actually one of the more protected oil pans iv seen on any car without a skidplate.

[alteredimage240sx]

Thanks vancouver, I will definitely take a look at that sensor and the manual. To answer both replies, the first thing we thought of was the oil pump and pickup. The damage to the pan was in the front, and we replaced the pan, hoping maybe it had just pinched the pickup. Nothing inside looked damaged, and but the same problem happened, where the light stayed on, and noise continued etc. I was thinking the pump it's self may have to be replaced because of the severity of the hit to the pan. It's about 350 bucks + tax at AutoZone. The dealership wants around 500 I think. Do you guys think it's worth it to replace it, or should I just swap in the 96 KA24DE that we bought for her just in case? I just really need the car on the road, as I'm spending 200 bucks every two weeks on gas for our truck. I'm just looking for honest opinions as the engine that is in the car ran really strong and still does, but with noise. The one we bought the 96, has about 30,000 less miles on it, but this one th 91 I know wasn't beat on. She wanted to get up and go once we got it started. So I'm conflicted. What would you guys do, in my position?

[vancouverbc]

here is oil pump inspection article

zerothread?id=161684

You might be able to rent a oil pressure gauge free from some parts places. The gauges are cheap ie 30 dollars?

[alteredimage240sx]

Thanks Vancouver, I will look into that option. I'll let you know what happens!