Hello,

Any idea on where to check for a grinding sound on start up or idle? I will be idling at a light and I will hear a grinding. If I could tell it sounds like it is metal on metal but I do not know where to start. I will hear it when I am at low speeds or turning too. I would like to add that when I am driving on the freeway I do not hear the grinding.

We can try to help but you'll need to elaborate on this noise. Does the noise get louder and/or correspond with how fast the engine is revving? Is it a ticking noise or does it constantly sound like metal is grinding?

Does it make this noise no matter what gear you are in? How does the truck run, any other issues that may be related?

What year and mileage too.

Truck runs great. It’s a 97’ with about 280k on it. I was only able to hear it this morning when I was in the drive thru and accelerating at low speeds. I got a sound clip of it that I will post soon but I was able to hear it from the drivers side pretty clear. It sounds like metal on metal, kind of like when you run a spoon at the bottom of a pan.

Check to see if the fly wheel is grinding against anything. Had this happen to me and it turned out to be a loose bolt grinding on the fly wheel.

Is it a manual or automatic? Could be a throw out bearing, alternator bearing, water pump bearing, A/C compressor drive pulley bearing, A/C belt tensioner pulley bearing. Could also be power steering pump, or timing belt idler or tensioner rollers, but I doubt it. Get a mechanics stethoscope from Amazon or the local parts store and use it to isolate the noise.

stethoscope is one of my goto tools for issues like you might have. I have listened to my 4runner a lot, just to learn its normal "heart beat"...its kind of fun. Most come with about a 1 foot or more longer "needle" to pin point tight areas. Harbor freight sells them too.
just be careful putting near rotating parts and belts

you can also use a long hose, even a long ratchet extension to "listen" too, but the stethoscope works better

I like to pull the needle part out of the stethoscope and just use the hose part to find small exhaust leaks (like a cracked manifold under a heat shield) or which pulley is causing a belt chirp. You know, stuff that you can't really touch anything to.

I will go and source a stethoscope for poking around. One thing I did notice is that when I am idling at a light (foot on brake) and after a 10 or so seconds the grinding will begin but it is at random times. I noticed when I place the car into Park the grinding sound comes to a halt the moment I do so.

Edit: Will upload sound soon.

I would like to add that it is a 1997 2WD Automatic.

Quick update:

The issue has been resolved. Broken Catalytic Converter. Even at worse the shop I was at pointed out that I had a 2" 1/4" and not a 2" 1/2". My previous mileage was about 16/17 MPG, now its up to 19/20 MPG (this is with combined city/highway, 60 -70 MPH speeds.

I noticed that the sound would be at it's worst when I was a slight incline or going up hills. I noticed the sound would go away when I was at a slight decline or going downhill. I proved this while driving around Pasadena on that weekend. It was only until I pulled into the driveway (which has a small slope typical with California homes) that I noticed the sound started up again. I placed the car into park, parking break, jumped out, grabbed my extendable magnet and looked under the car. I told my girlfriend to put the car into drive with the parking break on and behold, the exhaust was rattling and shaking around. I placed my magnet on the cat and it was shaking my magnet.

Must have cracked it or something? I hit a massive pot hole in January that jacked up my suspension.