celtsean

iTrader: (1)

Mostly stock 2000 trans am 96xxx miles, magnaflow cat back, egr block off. Tapping light knock at idle that traces rpm but is inaudible at 1500 rpms and up. I'm terrified its rod knock. Any way I took it to a mechanic he said he couldn't figure out exactly what or where it's coming from. Neither could I ,because I can hear it with a stethascope in different spots all over top to bottom. Oil pressure is good, no silver in oil. Anybody have any ideas? I mean , should I just ignore unless it gets worse? I don't think my ocd will let me lol.

Mercier

iTrader: (15)

Sure it's not the start of an exhaust leak? Lifter hopefully if something internal. Can try a flush with Seafoam or similar or $100 gets you a new set of LS7 lifters. I had a plug wire going bad and the spark jumping out of it made a scary lifter knock/tap sound.

What led up to this?

celtsean

iTrader: (1)

It has made a little of this sound for awhile . It just seems to have gotten a little louder now. I have run the seafoam through it , the three part cleaning. I'm sure it cleaned it out a bit but no effect on the sound. And I won't run the seafoam more than every year or year and a half. It seems like lifter noise would be a little faster. I may end up having to do my first lifter job. Right when I'm getting ready to put new koni strt shocks and some lowering springs. And my budget is at maximum overload.I can't take the stock de carbons any more ,it's way overdue. Now this noise just makes me nervous. What led up to this is a long story. This car sat for three years after I got a dui here in ca. I got it back on the road and since then I've learned all I know about cars and ls1s in general. It got all new plugs, wires, all new fluids tranny,dif, coolant. Various other stuff pcv replacement, I had a vacuum leak.Otherwise nothing major leading up to this. This noise is seeming louder , seems like it would get quiter when warm before. I don't know if I am confusing sounds though. On cold start up its hard to tell what is piston slap and what is that noise.

Mercier

iTrader: (15)

What kind/weight of oil are you running? How does the engine run otherwise?

celtsean

iTrader: (1)

Penzoil platinum 5w 30. Actually I think it liked the 0w 30 Belgium castrol better. I used to run mobil 1 but it seems to burn and she consumes more. Really seems to run pretty good, no power loss. Only thing I notice is it seems like it has a slight misfire at idle. Never throws a code for it and doesn't do it at high rpm. People tell me that I'm overly concerned when I point it out to them.

celtsean

iTrader: (1)

And it doesn't make the noise on cold start till it gets a little warmer. Like about 130 or so Id have to put in on the scanner on cold start to see the real temp. But it doesn't start doing it for a few min.

lynx853

iTrader: (8)

Lifter, they are known for issues on these engines. Mine did it only sometimes when cold, but most the time it when it was warming up but not yet hot.

there's some you tube vids on how to clean them in car, which is your first option. After that you would pull the head and clean them, or I would just throw in a new set.

lynx853

iTrader: (8)

re-reading and seeing you are on a budget,

here ya go!

Mercier

iTrader: (15)

Sounds like you have your answer.. If you want to hear something interesting, pull a plug wire off a coil and listen to the tick..scary similar to a lifter tick.

Mercier

iTrader: (15)

Guy did a nice vid. I wouldn't have thought to just clean the individual lifters like that. Great idea.

But I have to LOL at "DIESELGAS!!!!"

celtsean

iTrader: (1)

The only thing is it's way louder under the car. Its not near as audible on the top of the engine. I thought lifter noise would be more up top. Yeah, I've pulled wires trying to isolate one cylander to see if it would quiet the noise. It ticks pretty loud. 37 psi at hot idle isn't bad oil pressure is it?

Mercier

iTrader: (15)

That's good hot idle pressure. Some would be envious.

Noises reflect off the ground and can fool you with a quickness. Same reason dumps are so damn loud. Nothing to stop the sound waves from dissipating out of the top of the engine. How sure are you that it isn't an exhaust leak?

celtsean

iTrader: (1)

I wouldn't say I'm sure by any means. But I can't find it if it is. And I see no evidence of one. Can you hear an exhaust leak with a stethascope from different parts of the engine? Because I can hear it in the metal of the valve covers , top of exhsust manifold, and the oil pan and bell housing.

Mercier

iTrader: (15)

Huh. Shouldn't hear it in a valve cover. But even listening to that on some good speakers I'd bet my lunch money that's not a rod. From my listening, that's a tick/tap, not a /knock./ Any time I've heard real knock it's obvious there is something bad wrong. But there is still the possibility that it is the start of something worse. I don't think so though but I can't check it out in person.

M6 or A4? If the former, does it change at all when you press the clutch? I've had plenty of throwout bearings sound JUST like that. Also a pilot bearing. A4 would be interesting to see if it is different in park vs. drive, reverse.

celtsean

iTrader: (1)

M6,and no it doesn't change at all with the clutch pushed in. I'm gonna take off the belts and run it and see if it could be somewhere in there. The belts are new , and I greased most of the pulleys but i am getting some non squeek non chirp sound from there as well. Allmost like a chirp without the squeek part of the sound. It sounds like bad bearings. A shhk shk without a rhythm. So maybe the light tapping is coming from there as well.

Mercier

iTrader: (15)

Air seeping past the oil fill cap due to PCV vacuum has caused some funny noises. Try taking it off while running and see if the noise changes. Trying without belt is a good idea too.

lynx853

iTrader: (8)

keep it simple,

address one issue and move to the next. The lifter cleaning fix is where I would start. If it doesn't work, move to the next possible culprit.

celtsean

iTrader: (1)

Yeah, you're probably right. I'll try and get on that this weekend. Thanks a bunch for all your help. You and Mercier have made it a lot easier. I really appreciate this forum. I've learned most of what I know about f- bodies on here.

lynx853

iTrader: (8)

just keep reading man, I've been lurking since 2005! Also an ASE and ford master certified mechanic.

comes down to patience, not overthinking things and, creating a process and following it.

hope everything goes well! F bodies can be a pain to work on with the cowl... I've took more of a liking to my truck! but they are relatively simple, and fun.

Mercier

iTrader: (15)

The cowl is what always kept me in Mustangs.. You can pop the hood and see the whole engine!! Now with a swap project though I am so glad I'm not fumbling around with 4 fricken cams.