ljobbins

Ok, here is my problem. I suddenly have a super loud noise coming from the engine compartment that sounds like grinding or a crazy fast vibration, like metal-on-metal, which obviously is not good at all. The car ran perfectly fine, then on one start it had this noise. It wasn't faint and grew louder, it was on at full blast. It goes on and off at random, doesn't matter if i'm at idle or moving, but it does get louder when it revs up, so rpms make a difference. To give you an idea of the magnitude of the sound, I was at a stop light next to a turbocharged diesel f-250 and he gunned it off the light and I couldn't hear him because my noise was so loud. Things I have done/checked since it started: checked oil level(good), changed belt and idle pulley, checked all pulleys(good no sound and spun well and straight), took out distributor and connected a drill to it and it spun great with no sound, changed distributor cap and rotor with cruisers distributor setting tip. I don't have an oil pressure gauge but the dummy light tests good on start up and I recently changed the oil pressure sender so it should give me a light if the pressure was no good. I've driven it several times since the noise started because it's my daily driver and it hasn't seized or noticeably dropped mpgs, or had acceleration problems. My schedule is very busy most of the time and funds are low as i'm going to college full-time so I want to narrow a possible problem down before I have to start disassembling the head or block(which I don't want to do with my time constraints but I will as a last resort). Sorry for the long post but I wanted to get as many details as possible. As always, thanks for help.

Larry's XJ

As they say around here, ya gotta do some more noggin pokin.

Is noise front, back, left, right, top, bottom side of engine?
You need to narrow it down for us.

Not flaming but spacing/paragraphs make for easier reading.

SteveMongr

harmonic balancer perhaps.

ljobbins

Well it's so loud when it happens that I can't pinpoint an area. I don't have one of the stethoscopes either. Is there anywhere that can let me borrow one like autozone or somewhere, or any ideas on how to isolate noises to only hear one area at a time?

ljobbins

Is there a way to check that? I did put the car in neutral when the belt was off and rotated the crankshaft pulley and didn't hear anything or feel any resistance like scraping or such but it may just turn to slow by hand to hear a problem.

ljobbins

So I found the problem. It was my alternator going bad.

As I was driving the battery light came on then within 5 seconds I see tons of smoke coming from under the hood which freaked me out thinking there was a fire, then 2 seconds later the power steering went out and I knew the belt broke. Parked on the side of the road and my alternator was frozen and smoking and the belt melted and broke. It was weird because the day before when I took off the belt it turned perfect with no sound.

Got a ride to get a new one, swapped it, one hour later the jeeps running perfect again and noise gone. Thank God it wasn't internal at all.