1993 3.4 TDC, ~90,000 miles on the motor, but I had the crank reground and installed new bearings right before I put it in the car (1,000 miles ago). I've been having a high idle problem lately, as well as some electrical issues (slow blinkers, lights dim) due to what I suspect is bad grounds.
On the way to school yesterday, I got stuck in traffic with the high idle, so I just shut off the engine and coasted where I could (downhill) and yelled at my motor to quiet down when I had to run it to move along. When I get to school, I find a parallel parking spot on a slight uphill slope. I go past it, start backing in, and then my idle drops to like 100 RPM (or less) according to the tach. Sure sounded like it was spinning that slow or slower. Making a BOP BOP BOP BOP BOP BOP BOP as it spun. It took me a few seconds to grasp what was happening and I noticed the oil pressure light was on (gauge was low but I dont know if it actually read zero). so I shut off the engine and waited about a minute. I tried to start it again and it started right up and tried idling at 100 RPM with negligible oil pressure. It didnt seem to want to change or idle up so I shut it off again, put my paperclip on the ALDL terminals, and turned the ignition to run so it reset the IAC. Finally I tried to start it again and it ran fine with the same oil pressure it normally does. I finished parking and went to class. I was very paranoid on the way home, thinking I messed up my brand new bearings from it idling so low without much or any oil pressure. When I shut off my engine in my driveway I noticed it was significantly louder as it spun down than it used to be. It makes a few loud sounds like "TOT" as it spins down.
Recalling that it made very little or no oil pressure as it spun slowly, I decided tonight to try just turning it over with the fuel pump fuse out to see how much pressure it made. It was out of the red zone. I went for a test drive to warm it up, came back, turned it off (now it made the loud "TOT TOT TOT" sound as it spun down; though I dont recall if it did that cold I don't think it did), and turned it over with the fuel pump fuse out again. This time it didn't make much oil pressure, but I was more concerned about the fact that it also sounded a lot louder.
There is no knocking at any RPM by the way. Oil pressure is perfectly fine. I've driven it hard since and haven't spun a bearing. Should I even be worried?
It's possible that the loud sounds after being turned off hot were there before and it was louder cranking over hot and I just didnt notice or pay attention since I had no worries. Maybe its just now that I'm afraid my bottom end is messed up that I'm really listening for it. Somehow it doesn't make sense that the bearings should suffer much damage just from idling for a few seconds without much oil pressure; its not like they were dry.. nor was it revving high.. I thought the engine doesnt have oil pressure for a few seconds at normal idle of 1000 RPM right after an oil drain and refill anyway.. So am I just crazy or what? How do your engines sound when you shut them off hot? Should I replace all my bearings? And how do I prevent this from happening again? I can't figure out how the dang thing could even idle that low.. but it was spinning by itself, in neutral, with no load. Funky stuff. I hope I'm just overreacting here. After all, the oil pump obviously didn't fail.. it was just whatever was caused by Mr. No Good Low Idle.
Thanks for the therapy, folks.

I'm not an engine specialist by any means, nor am I very familiar with the 3.4 TDC. However, I do not think that you did much (if any) damage to the bottom end. I calculated it, and if it was running at 100 RPM, then it made 1.666 (you get the idea) revolutions per second. If it was running for a few (we'll say 3) seconds at low pressure, then it only made about 5 revolutions altogether with low pressure. That is not very much time woth low pressure, so I'd say that you're probably alright, and the noise you're hearing has always been there. I do that with my car when I think I have a problem, and I magically just start hearing noises that have always been there. Like I said, I'm not an engine specialist, so I could be wrong. Good luck.
-Will

Exact same thing happened to me last month:

https://www.fiero.nl/forum/Forum2/HTML/062337.html

I've changed my plugs and did a tune-up and still have that tocking (tot) sound when turning on the car and when turning off. Note, it doesn't making any tocking sound when idling or driving through any rpm range, even redline. If you find any info, that would be cool as I'm worried.

quote Originally posted by Pontiac Boi: Exact same thing happened to me last month: https://www.fiero.nl/forum/Forum2/HTML/062337.html I've changed my plugs and did a tune-up and still have that tocking (tot) sound when turning on the car and when turning off. Note, it doesn't making any tocking sound when idling or driving through any rpm range, even redline. If you find any info, that would be cool as I'm worried.

That is so bizarre! I'm glad I'm not alone on this boat. Yeah, there's no sounds while running at any RPM under any amount of load.. just right at shutdown. Kinda weird that we'd experience something unrelated like dieseling after the same incident, eh? What I figure is if no damage was done by the low oil pressure for a bit, its just paranoia causing more awareness of engine sounds and its been happening all along. Gonna run seafoam through tomorrow to see if decarbonizing helps any...

-Steven

Weird, my noise is coming from the right side as well. When I changed the oil, I did find very very little tiny silver pieces like what you explained.

This may sound odd, but it might be worth a try. At so low RPM, I'm thinking it might be the bearings in the alternator or some other accessory. I'm going to replace the alt sometime next week and hope for the best. In the meantime, the past month I've been driving with no problems, and the noise hasn't gotten any worse and still doesn't do it while driving or idling.

Ok, for the silver pieces I think I figured it out. Its NOT bearing chunks. Look at your drain plug. Stripped threads and silver? Stick your finger on the threads for the drain plug and take a look at what gets on it. All those little slivers.. but there's none suspended in the oil. I ran my engine before draining the oil; if there was metal floating around it would be suspended in the oil but none is; its just when the oil first comes out because it picks up those bits from the plug threads. Whew. Definitely gonna have to pick up a new drain plug! Still, the bearings may have been damaged so I'm letting all the remaining oil drain out overnight so I can drop the pan and take a look at the bearings tomorrow or possibly later.
As for the alternator, I did run a different alternator on my car the day before yesterday to try and fix some other problems. I can't recall whether or not in made the tocking sound with that alternator on, though. Now that I think of it, I may have heard a knock-like sound coming directly from the alternator BEFORE I had the low idle/low oil pressure incident. I can't recall for sure though. Its definitely worth checking out.
If you listen very carefully from different angles to the car, you don't hear any tapping or knocking whatsoever? I heard an obvious sound from many feet away this morning, but I couldn't hear it above the exhaust if I was behind or inside the car. It was just present at regular idle ~900-1000 RPM cold. Didn't let the car warm up enough today to see if it went away, I just parked it and drained the oil.

[This message has been edited by Steven Snyder (edited 05-28-2005).]

Steven-

I'm wondering, since that beast has a timing belt AND an accessory belt, is it possible that you have a piece of grease or something on one of your pullies that makes the "Tock" every time it hits the belt? It might only do it on shut down because the pulley tension is lessened. Something to check into...

------------------
-Rick Stewart
85GT 5.0CaddyV8/Getrag 5-spd in progress...
www.V8Fiero.com

[This message has been edited by GT (edited 05-28-2005).]

Just checked the pulleys. They're all clean and spin free.

Pontiac Boi, I noticed in your other thread you mentioned that you had an oil change less than 1000 miles ago. Did you start using a different oil? I just remembered that on Monday I switched over to Torco synthetic. Its the same weight as my old oil, but I was just using regular Chevron oil before. I don't know what the previous owner used. Certainly could be a coincidence that I switched over just a day and a half before noticing the knocking at shutdown.. but worth checking into.

Stuck with the same oil, Mobil1 synthetic. I'm thinking it might be the bearings on the alternator or some other accessory like the waterpump or AC. The RPMs went down so low, maybe the alt had a hard time charging, and the bearings are making the noise on shutdown? Just a possibility, I think that's the most logical scenario. If it was lifters or bearings, the noise would be constant even during idle and especially high RPM driving. I'll be changing the alternator next week, I hope for the best, I'll keep you updated.

#3 or #4, can't remember. Its really hard to tell in the pic due to the glare but the very middle has more shiny area than the rest.

This one's #1. There is a groove in it that I can feel with my fingernail. Note that I didnt take this pic under the same lighting conditions, thats why the whole bearing appears dull. The lighter spots are just shiny areas on the first bearing. The darker spots in the middle don't actually look like they do in the pic, they are just duller patches that can be seen at just the right angle; they aren't actually dark spots.

The uneven wear concerns me. These bearings have less than 1500 miles on them.
How do I tell if the bearing is in a cylinder that has been knocking?

What gets oiled first?

EDIT: I looked at the top side of rod bearing #1. It looks similar to the bottom but the center wear area is wider. I can't tell how much of it isn't shiny though. I didn't actually take the shell out. I'm in the process of dropping the cradle so I can put the engine on a stand for better access. Its a PITA trying to take off rod bearings under the car. I have other stuff to do while its out anyway.

[This message has been edited by Steven Snyder (edited 05-30-2005).]

Did you ever get this resolved?

Just yesterday the tocking noise isn't just on startup and turning off. It only does it at idle, when I rev it or drive it doesn't make it whatsoever. But once I go to a stop and idle, it tocks. The sound is coming from the right side where the pullies are. I set the idle to 1100 and the tocking noise is no longer there, but it's still there at startup and off.

If anyone has any clue about this, let me know please.

What you're hearing is rod or main knock.. or both.
Yeah, I pulled apart my engine and all my bearings are F*?*&). Something produced metal bits and scored everything. Some of the mains have gouges that go into the copper. I don't know if bits produced by the bearings during that small period of low idle/low pressure went through the rest of the bearings and killed stuff or if I had metal in the engine from the start, but either way its time for a rebuild.. Sorry!

[This message has been edited by Steven Snyder (edited 06-09-2005).]

One moment of low idle

Lessons learned:
-Don't lug around at low RPMs. (see Pontiac Boi's thread)
-Fix idle and other electrical issues right away. If possible do not drive except for tests while these problems are present.

Steven, BOI-

It just occurred to me when I rebuilt my TDC that the only TOC sound I ever heard during assembly was when I turned the oil pump by hand with the shaft. If I recall, by changing directions with the shaft it would make a kind of TOC sound at every change in direction, know what I mean? Is it possible you guys have a worn pump or a worn shaft or something oil pump related? I know I'm grabbing at straws but something must have caused all that metal in your oil.

-Rick

My oil pump appears to be fine, though I haven't looked inside it yet. The shaft feels right when its spinning the oil pump and all.. plus my oil pressure was fine at normal idle.
The quantity of metal was very low in my oil. I had to drain it all and carefully look at the bottom of my drain pain to see that there were some little specks. It could certainly have just been from the bearings, especially considering the deep gouges in a few of them, though that would mean that all the damage was caused in those few seconds and not from debris in the engine during assembly. I would hope a properly running motor couldn't have its bearings trashed in just a few seconds like that!