What do you think it is? When I park it and rev the engine (hard or easy) it does not happen. It's only under a slight load that I can hear it, like taking off and when the auto trans is changin gears.

I tightened down the tail pipes and moved them away from the body of the car. It doesn't sound like an exhaust leak to me.

It's jsut annoying right now...

Thanks in advance for the help. Have a listen:

Well, I hate to say this but it sure sounds like a rod knock to me. But I cant say for sure unless I could see the car in person.

It sounds to me like the exhaust is smacking the cradle.

The engine tends to pull the exhaust upward when accelerating, and it sounds to me like the exhaust pipe is getting lifted till it starts to vibrate against the hump on the cradle under light load, under heavy load it will be in full contact with the cradle so it will stop smacking the cradle making that noise.

Just a guess, but it seems to fit the sound and description well, even though mensioned that you have pulled the exhaust from the body.

Try pushing the pipe up by hand (when its cool, duh) and see if it makes the sound.

Sorry to say it but I also think it sounds like a rod knock.

Dead-on rod knock sound right there. I had an engine with rod knock sounded just like that, not horribly loud, but very solid.

Try the exhaust thing first though just in case.

Thats rod knock, also look at the oil pressure in the video....lots of clearance in that motor.

quote Originally posted by pontiacking: Thats rod knock, also look at the oil pressure in the video....lots of clearance in that motor.

Good point, your oil pressure is really low for those RPMs.

I would say it's rod knock. Pontiacking is also right, the oil pressure is very low. my oil pressure is around 40PSI at idle.

Of course, I'm hoping that Fieroobsessed is right.

I omly tightened the tail pipes. I remember the lower-front pipe that holds the cat seemed off center. The passenger side seemed closer to the cradle than the other side.

I'll get under there tomorrow and see what I can do.

Thanks for the input!

Could be a rod knock, but also check your harmonic damper as well. When the outer ring starts to move it can bang on the timing cover pretty good.

What is the RPM for that noise ? If it's between 2,500 and 3,500 It's a rod knock ( if you shift and it goes away until you reach those RPM again , that is )
Happened to me last summer . Had to rebuild the engine .
Wish it's not after all the work you put in it .

EDIT
I just looked at the video and it sure look in that range on the Tach

[This message has been edited by Robert 2 (edited 04-02-2008).]

Thanks for noticing the oil pressure. It is close to 40 when at idle, so I assumed it was good when I was accelerating.

I'll check some other things underneath first. I was told this engine was rebuilt just 5,000 miles (and 4 years) ago.

I may be in search of a Camaro 3.4 in the near future...

quote Originally posted by Saxman: Thanks for noticing the oil pressure. It is close to 40 when at idle, so I assumed it was good when I was accelerating.

In your vid it looks to barely leave the Red when you accelerated away. When I first start mine its near pegged, fully warm idle its a bit over 1/4 of the gauge, and cruising its around 40.

Could be a rod knock. Drop your pan and check the rod bearings. If you're LUCKY, you can get away with just replacing the bearing. Examine and mike the journal, and check the rod also. I was lucky with a duke. I had a spun rod bearing. The journal and rod were still good, so I just replaced the bearing. Actually, I replaced all of the rod bearings. The knock went away, the oil pressure went up, and I've put a few thousand miles on it since with no engine problems.

It looks as if you have a bunch of good mechanics giving you their best shot at the sound on the video. I have to add my two cents to the rod knock. It is a classic rod knock sound. If you haven't dropped the pan yet I would soon. It can only progress each time it is run. Good luck.

Rod knock. Been there, done that. Sorry, man.

------------------
1986 SE 350 V8

Time for a rebuild. Sorry dude, even if the oil pressure showed 'normal' it would make the
same sound. Just for sh#t's and giggles, try 50W oil and see if the sound fades. It probably will,
but not for long.

Cordially,
Kevin

Could your exhaust manifolds be leaking?


Scratch that... I just noticed that your oil pressure is pretty low. My '88 GT did that back in '96 on the highway. It was a small tick at 70mph that turned into a loud jackhammer like sound by the time I pulled over and my oil pressue was extremely low. Turned out I had a bearing knock. Good luck, hate to see a sick Formula.

=-Eric the Dread

[This message has been edited by 88 Dread GT (edited 04-02-2008).]

Well, I went ahead and sealed a deal on a 1,000-mile Jasper 3.4 engine. The engine was installed on the guy's Camaro, then he turned around and put it in a ditch. I have to take the whole car. It's a salvage title. He is giving me receipts for the engine install.

He says it only has 1,000 miles since the dealer installed it. The car has been sitting for two years and still starts up.

I imagine I can sell some of the Camaro parts since just the front bumper appears to be ruined - and the bent radiator support brace is part of the reason for the salvage title. Repairs would have cost $6k. I think the tires/wheels are new, too.

Did I mention that I got the whole car for $500? Now to go buy a starter relocation kit at the Fiero Store!

My 85 has that same knock but has been running longer like that then yours so it its become much louder. The previous owner told me he thought it was a collasped lifter lol. My fault for not waiting to charge and start it before i bought it though. Good luck.

quote Originally posted by Saxman: Well, I went ahead and sealed a deal on a 1,000-mile Jasper 3.4 engine. The engine was installed on the guy's Camaro, then he turned around and put it in a ditch. I have to take the whole car. It's a salvage title. He is giving me receipts for the engine install. He says it only has 1,000 miles since the dealer installed it. The car has been sitting for two years and still starts up. I imagine I can sell some of the Camaro parts since just the front bumper appears to be ruined - and the bent radiator support brace is part of the reason for the salvage title. Repairs would have cost $6k. I think the tires/wheels are new, too. Did I mention that I got the whole car for $500? Now to go buy a starter relocation kit at the Fiero Store!

Some corrections since I actually got the Camaro home:

It's a 1,500-mile Jasper remanufactured 3.4- and I just pulled it out tonight. The car has a regular Virginia title - not a salvage. The kid just never made an insurance claim to keep his rates from skyrocketing.

My neighbor is buying the rest of the Camaro for whay I paid for all of it - and he still got a great deal for all the parts he is taking off it. T-tops, tires/wheels and interior are very nice - plus the junk yard will pay him for what's left of the car.

I got the starter relocation jig, too, so that comes next!

The registration should be here Tuesday, so I will drive the car much more to see if the knock gets worse. I also have new plugs and I am going to check the EGR to see if it is clogged. I'm still holding out hope! (But I also have the starter relocation jig on the 3.4 block just in case see https://www.fiero.nl/forum/Forum2/HTML/092962.html )