Alright guys, here’s the deal. Sorry for what might be considered a long post. I have two separate issues and I doubt they’re related.

2000 4Runner Limited, 4x4, 208,000 miles

The first, potentially more pressing issue:
On Friday, I was leaving my office and went to start the 4Runner. It did start, but it started a tad bit slowly and immediately there was a pretty nasty grinding noise that seemed to be coming from the bottom end. I took a video and sent it to my mechanically inclined friend (I don’t know jack squat about working on cars) and he said it sounded like a belt that was about to snap. Checked all visible belts, they were fine. He also said it could be a pulley. Unlike other grinding issues I found on this forum, it makes the noise no matter what – in park, in neutral, in reverse, and driving. I got it up to about 45 in the parking lot and it drove COMPLETELY normally with the exception of the noise. The noise did not get LOUDER as the speed increased, but the frequency of the noise increased under load if that makes sense - think about how supercharger whine increases w/revs - same concept. No CEL’s, no bad smells. I know it can’t be the driveshaft/driveline because it did it whether I was in gear or not. Additionally, MPG has been down a bit for the past couple tanks’ worth of gas (maybe just by 1mpg, nothing drastic) but it's probably unrelated. Just want to get all info out there.

Anyway, I decided to try and get it home – not only did I make it home, but about ¾ of the way through my 20 minute commute, the sound went away completely and hasn’t been back. The video I took is below and is fairly representative of the sound. The best representation of the sound is at the end when I put the camera under the car. It was louder and more pronounced in person, but the camera did a pretty good job of capturing it. I’m primarily concerned because I have a two hour road trip this weekend and don’t want to have to deal with a breakdown/tow/getting it fixed 2 hours from home nor to I want to cause any more damage if continuing to drive it will do so.

Any idea what this could have been, and should I do anything about it or leave well enough alone? Any suggestions will be heeded as soon as my mechanically-inclined friend becomes available. I know myself and I know I'll make it worse if I dive in myself.

Video is here: https://youtu.be/hE9gear9xoM
As mentioned above, the best representation of the noise is at the end when I'm under the car with the camera.

The next issue:
Very intermittently, it will not start the first time. Sometimes it’ll start up the second time, and sometimes it’ll take up to 5 times. When it doesn’t start, there’s no clicking…the motor just stops attempting to crank until I turn the key and try again. I know that starter contacts are a fairly common problem, and I know starters seem to go out fairly commonly on these too. Any way to tell if it’s the starter itself going bad, the contacts going bad, or both? I have a friend who owns a 2000 Solara and his did something similar - he ignored it and it eventually started a small fire in his engine bay that narrowly missed the ECU. I would obviously like to avoid that.

Thank you in advance for your input - you guys are the best on the internet when it comes to this stuff.

Sounds like something is chewing up the flex plate. Maybe a sticking starter gear?
I wouldn't run the engine again until I checked otherwise to minimize the damage.
Only way to rule out the starter is to get underneath and remove the starter and check it's teeth.

Hey Steve, I had an issue with my starter where the starter stayed engaged even when I turned the motor off. When I took the starter solenoid apart, I noticed one copper contact gets more worn down than the other side. Because of this, I believe the plunger can get cocked crooked and get stuck. When this happened to me, luckily I was at home and I quickly grabbed a pair of channel locks and removed the negative battery cable to stop the starter from trying to turn over the engine.

Since you are having starting issues, I suspect you had a similar thing happen. I'd pull the starter and look at the gear. I'm suspecting with the extended grinding you had going on, your starter is probably toast. If the starter gear is indeed damaged, I'd inspect your flex plate next. There's an access cover on the bottom of the bell housing that's held on with (4) 12mm bolts. When you have the cover off, you can get a good look at the flex plate gear teeth. To see the whole circumference, get a 1/2" ratchet of breaker bar with a 19mm socket and turn your crank bolt clockwise to rotate the engine and see more of the flex plate. Hopefully you didn't eat up any of the teeth on the flex plate.

But, I may be completely wrong and the source of the noise is something else entirely. Good luck!

Edit: @HiLife beat me to it.

Thanks for the replies, guys.

Since I'm about as ignorant as they come, that leads to a few more questions:

1) Assuming you guys are correct about what's causing this, and assuming the flex plate is NOT damaged, will a new starter solve this problem? The intermittent starting issue has been going on for several months, so I have a feeling the starter probably needs replaced one way or another.

2) Assuming you guys are correct what's causing this and the flex plate IS damaged, where does that leave me? I don't even know what a flex plate is, but searching around the internet for flex plate repair bills made me gasp in horror (~2,000) and it looks like a lot of labor with equipment I don't have if I were to try it myself. Is it ok to drive with a flex plate that's missing a few teeth if it has a brand new starter?

A new starter could fix the problem. But, if the starter gear grinding on the flex plate gear caused damage to the flex plate, you might need a new flex plate which is a ton of labor to replace because the transmission has to come out. The flex plate gear teeth are pretty beefy so there's a chance there isn't any significant damage.

To start, pull the starter and inspect the teeth on the starter gear. I'm suspecting it will be chewed up. If the the gear is still intact, maybe a fresh set of solenoid contacts and plunger will fix the starter.

Here's a video you can use to pull the starter:



To learn how to remove the bell housing inspection plate so you can inspect the flex plate, check out this video. Go to play time 17:03 and I describe what you need to do.