Alright...I just recently did an oil change on my 94 Z28 and about 100 miles later...Im getting this serious metal on metal sound comming from the engine when its under load and at idle when i rev it up a bit i get these small metal bits comming out at my face....SH*T...I used the Castrol GTX High Mileage stuff (the car has 175k on it) just to try it out...is it the oil thats screwin me over or is my engine on its way out...please help!

Tell us about these small metal bits coming out and hitting you in the face! Coming from where?

they're comming out of the left side tailpipe.

Uh, let's see here, grinding noises and flying metal pieces? This is a real long shot, but I'd have to say that your engine is toast.

but why would it just randomly do it like this...i just had the heads and pistons re-worked about 5 months ago...and it just started doing this after this oil change...i mean i am leaning toward the engine is gone but its never exhibited this kinda stuff before...i usually always use the Quaker State high RPM or Castrol full synthetic...but with this stuff all hell has broken loose.

draw an oil sample and have it lab tested... if its the engine going out, the results will show high metal content like lead, chrome, steel, alum. etc. If that is the result of the tests, something let go inside, bummer. Id go back to who ever did the re-working on your heads and pistons and ask them what to do next.

Sounds like you burnt a valve. If it was serious such as crank\rods\bearings\cam then the metal would not be exiting through the exhaust. Pull the heads off and you should see your problem. Does the car overheat?

I seriously doubt little metal bits coming out the tailpipe are coming from the engine unless you have pulled the cat and muffler off the car. The Cat would catch anything coming from the engine and eventually plug up and if the cats are gone anything of any substantial size would settle in the muffler when the flow velocity of the exhaust stream dropped as it entered the muffler.

Uh, let's see here, grinding noises and flying metal pieces? This is a real long shot, but I'd have to say that your engine is toast.

That was useful.

Do you mean from area in the engine bay by the exhaust, or literally out the exhaust pipe?

If the latter, I would imagine the honeycomb in the converter wouldn't actually let anything through.

ok...the guy who helped me re-work everything is a friend of mine for 5 years...we were both doing them in his shop...i just took the beast out for a ride n the metal on metal sound has stopped...but there is now an AWFUL lag in 1st gear...not really sure if its engine of transmission tho...there is still "what seems to be metal" (either that or really really shiny dust) comming out the tailpipe...so im not really sure at all at this point...im actually draining the oil right now just figuring on a lucky shot that the oil i used sucked or sumthin...but i kno from expirience....life probably isnt gonna be that easy...and by the way...where could i get my oil "lab" tested?

Google usually finds everything you need.
Google oil test lab (http://www.testoil.com/)

Hmmm, Just my 2 cents, but could it be a converter rattle?? The last time I observed anything coming out of a tailpipe it was converter substrate.

That oil is fine that you used. Do you have oil pressure? I would have to agree on a plugged or bad cat converter. That would cause the lag. If your engine was shooting metal out the exhaust it wouldn't do it for long. :eek:

I have to ask: How do you rev it up with your face in front of the exhaust pipe? That is quite a trick.;)

I think you will find that one of the Cat converters has broken up inside and parts of it are coming out the tailpipe.

Check the CATS first

Check the CATS first I'm with Ed, sounds like 1 or both of the cats are done, with 175K they were done long ago, now they are just falling apart internally and coming out the pipes.

My 1st vote is for the CATS. Clogged Cats will effect vacuum so you can put a gauge on it to see how many inches its pulling.

cut that cat off! i had a car with one which got clogged up and my engine got toasted. cats are just bad news in my books.


i was going to say that metal coming out of the exhuast was carbon build up but since you reworked the heads it cant be that. i fired a engine up the other day without manifolds and it blew carbon bits at me and cut my hand!

I agree wit the cat thing...if ur using one? Kinda had the same prob with my 94 full size blazer, and it was the cat...almost the same symtoms you have. I do use the oil your talking about in the blazer and have never had a prob, and it's got 168000 on er'.

Metal on metal sound could be harmonic balancer bushing failure. I had one go on my '84 Z. Couldn't figure it out for awhile til I thought it was a little close to the timeing cover. Well it was so close it rubbed right through it...What a mess.

I have used Blackstonelabs.com for my analysis on a motorcycle. Go online to their site and they will send you a kit. It costs about $25 and you get the results with explanation in about a week emailed to you.

They also keep a record of all your analysis,,and put them on the form they return to you so you can see the trends over time.

by the way...where could i get my oil "lab" tested?

Thanks A LOT guyz...I got the car at my local high end shop right now...and yes...the cats are comming off....ive always hated them but its my daily driver so emission laws suck...but im tired of the way they make my car run anyways...the metal on metal has stopped and im deffinitely going with the cats do to the fact that the right bank has NO exhaust comming from it at all (explains the severe lack of gas mileage and performance) and the left bank is running extremely rich...so ... HOPEFULLY (crosses fingers)...nothing burned up on the way to the shop....but again...thanx a bunch

94T - The cat(s) may be the problem but removing them and not replacing them on your LT1 can result in less overall power unless you modify the computer programing. It also may set you up to fail a smog test...

Cats are not bad things on modern cars, like any part they can fail. I don't know if you have 2 cats or just one but can tell you that you don't have a true dual exhaust on that car. The exhaust runs through a "Y" pipe that send the exhaust back to the muffler through 1 pipe, then it splits it back out to 2 pipes after the muffler. It's called one in 2 out and depending on brand and design some never flow much out one side. That said you can't use what comes out the tail pipes as an indicator of balance from one set of cyls to the other...

no i understand that...but normally...both tips have if not equal a very close to same amount of exhaust comming out...but just recently it would only come out the left and none at all out the right...but im pretty sure its the cat...and i surely hope so cuz moneys tight...thanx again

Kinda sounds more like the muffler is plugged on one side. That would be less than a cat to replace. Extra back pressure might cause the problems you are having. Let us know what they find...

If you can collect some of the 'metal' coming from the exhaust with a rag over the pipe, use a magnet and see if it really is iron or steel. I agree with the faulty cats idea. I seriously doubt there is any way at all for engine metal to reach the end of a stock exhaust system. It has got to be something, muffler or cat, exhaust related.

Last year, my sons Ws6 developed a rattle in the cats, during the emission warranty,, We took it in to the dealer to check, sure nuff, cats came apart from inside and was rattling away, pieces and all. Not coverd under emission warranty said dealer , as during the earlier testing for back pressure (sic) we installed an automatic waste gate near the stock muffler. You have modified the factory exhaust, says the service man, no factory assistance is due but if you want you can have a muffler shop cut the cats off. I am thinking , the owners manual says , you are in enviromental violations if you do squat to cats within their warranty period!. An the dealer tells me this?
We cut them off and replaced with hi flow jobs,, Job done. Come get me feds, i need a new place to live. No bills, no rent and free lodging,, I ain't skeered.

Any good muffler shop can tell you in a few minutes if it is Cats or Clogged muffler and if it is Cats they can replace them with high flow ones and they are not that expensive and your computer and other related Emission controls will stay normal and working to give you the desired performance and fuel mileage. Go to F.Body.com 4th Gen site and you can get good info on this

Wow this thread is still going?

I have used Blackstonelabs.com for my analysis on a motorcycle. Go online to their site and they will send you a kit. It costs about $25 and you get the results with explanation in about a week emailed to you.

They also keep a record of all your analysis,,and put them on the form they return to you so you can see the trends over time.
I went to blackstonelabs.com and the site is gone and the name is foree sale did you typ the name in rite I could use them for my 62 3/4 chevy.
Bob

http://www.blackstone-labs.com :thumbsup: