clatter/rapping sound from DS header & V.C.

[Dr. Jeckel]

I started feeling my car was a little rough while driving today. Not much, just slightly different. I let it idle, opened up the hood and popped the throttle with my hand at the throttle body. If I popped it kinda quick to about 2500/3000(i'm guessing) you can hear a loud clatter/rapping noise coming from the valve cover/header area on the drivers side. It is a very quick, repititious, clattering. If I raise the rpms slowly you can't hear it that well because the noise of the engine kinda over powers the clatter. It kinda sounds like it could be a cracked header but I'm not real sure what that would sound like. You can't really hear anything outta the ordinary with it just idling, the cam makes it hard to hear an exhaust leak. The car runs good, despite the noise.
I just got through doing heads and cam. New springs, pushrods,lifters, felpro 1400 exhaust gaskets. It is a strange sound and hard to describe, it doesn't sound like metal to metal but is very fast, when the throttle is popped.
Anybody have any ideas? Thank you, James.

 

[Turbo Brian]

Very few driver's side headers did not crack over time. If it has not been repaired to your knowledge, it is more than likely cracked. If it has been repaired, there is still a potential that the job was not done properly. Pulling the driver's side header is not a particularly hard job.

You might find a vendor that repairs the headers on an exchange basis, so that you can order the part while you still are driving and then make the swap when the part arrives.

 

[Dr. Jeckel]

I did a compression test today with the engine warm, all plugs removed, I did not open the throttle blade to wot though.
I got these numbers:
#1-133 #2-140
#3-130 #4-127
#5-139 #6-133

Plugs had a little build up on a few of them and one was very slightly green at the tip.
I have had a few opinions, ranging from piston slap, knuckle pin, valves, exhaust leak, cracked flywheel.
Anybody have experience with any of these?
The sound is so general that it is hard to tell where it is from.
Need some help diagnosing my problem fellas.
Thanks, James.

 

[DR BOOST]

cracked rocker shaft or rod knock

cut your filter open and look for bearing material

 

[Dr. Jeckel]

I did cut open the filter and found alot of tiny metal flakes and the oil had a light glitter look to it. This is not good, but what I expected

 

[turbo nasty]

Did you do 4 "puffs" on each cyl for the test and use the average readings from them? 1 or 2 "puffs" is not the right way.

Could be this:
My 86 GN has a nut that is supposed to be welded to the a/c bracket where the a/c comp mounts broken off So it rattles slightly on the mount and at idle or cruise it sounds horrible, just like you discribed.

Drove me nuts till I found it.

 

[ulose2av6]

you also have a blown headgasket.

 

[Dr. Jeckel]

It was probably about 4 puffs, I did it until it stopped moving any higher. Also I doubt it is a blown head gasket. I have had no detonation and cometics don't just blow for no reason.
I took the valve covers off today and checked it all out. I started the car with the valve covers off and every rocker moved the same amount. I didn't check it with a gauge or anything so it could be wearing down. But not near enough to see with the naked eye.
Its just funny because the car still runs good. If it gets over 2,000rpm while driving then you feel a slight vibration and it sounds rough. But if you get into it a little it almost smooths out. I did about 1/3 throttle and up to 13psi boost on the highway and it spooled quick and ran smooth.
The sound doesn't sound like metal to metal but obviously somthing is shredding because of the shavings in the filter.
I am thinking about putting the stock cam back in and seeing what happens. Only problem is I don't remember which lifter went where. Is it a for sure no-no to put them back into different holes? Should I buy all new lifters when I swap it back in?
I am starting to think it didn't get any bearings because it just has a lumpy idle but there is no knocking/ticking just a rough feeling and an exhaust leak kinda sound above 2,000rpm. How likely is it that a bearing got wiped if the cam lobe wiped?
Anyone have anymore suggestions or opinions?

Thanks, James.

 

[FJM568]

Are you getting any knock retard on your Scanmaster??? My guess would be that you lost(or are losing) a lobe on the cam...Your symptoms sound really similar to mine when I wiped the #3 exh on my motor...Started to clatter real bad on the way home from work one day, parked the car at the end of the drive, left it idling while I got the mail and it was noisy...It was pulling so much timing out of it that it felt like I was running on 4 cyls or something...Before then, I would occasionally get a beep or two out of my knock detector while cruising on the highway or just everyday driving and could never find what it was...until it started clattering really bad...

But that is my guess...

On putting the old cam back in, yes, you can do that, but if you didn't keep track of what lifter went where, then you would have to put new lifters in and follow the break-in procedure again like you were putting a new cam in...

 

[ulose2av6]

you said that the tip of the spark plug is green that certainly is an indication that indeed the head gasket is blown or on the way out.

 

[blackbird]

CRANK!!!

that clanging sound might be your crankshaft getting ready to let go!! mine did that not too long ago and i thought it was a crack in the header

 

[Justaveesix]

Pull your oilpan off and check your bearings. I am in the middle of this right now. I had the same sound, which sounded like it ws from the valvecover area, turns out my #1 rod bearing is pounded. Time for new rod and main bearings.

If you want to check which rod it is, unplug your injector wires, one at a time, start the car and when you find the right cylinder there will be no knock or very little. Only unplug one injector wire at a time when doing this.

HTH