Go figure. Beautiful weather, NO ONE on the roads, and my 1971 started making a terrible banging/clanging noise. At first, from inside the car, it sounded like a loose exhaust component banging against the frame. It has gotten progressively worse in a hurry. It sounds like it is coming from the rear of the engine down towards the clutch area. It's a 350 with an replacement block, Edelbrock aluminum heads, intake, carb. 4 Speed. It has an aftermarket cam as well, all installed by the previous owner.

Some additional history...

The Made in Mexico 350 was installed 2 owners ago. The previous owner installed tall of the aftermarket parts - Heads, intake, carb, cam, MSD ignition, etc. I have had the car for several years now, and put around 4000 miles on it. There was a coolant leak into one of the rear cylinders - I believe #8. There was never any oil in the coolant or coolant in the oil, but it went through coolant and the right side exhaust would blow a little bit of white smoke and smelled like coolant. I had a friend who owns a repair shop service it last fall. They pulled the heads and determined that the leak was coming from one of the head bolts - there seemed to be no sealant on the bolts. In addition to all of the dis-assembly / re-assembly required to replace the head gaskets and seal all the bolts, they also removed the starter to install a missing flywheel shroud. I have had no cooling issues since then.

My friends' shop that did the last work is closed due to COVID, so I am appealing to the forum for help. Thanks in advance.

https://www.dropbox.com/s/336h296dhf...noise.mp4?dl=0

 

WAG 1
bad fan clutch permitting fan to hit shroud

WAG 2
bad rod bearing

 

Wag 3...
cover came once and coming off again?

 

I just now listened to youtube ... sounds bad.
Are you losing power noticeably ? If so, it's probably even worse than wag1or 2.

Is oil pressure normal ? any change ?

Water temp normal ? any change ?

 

Thanks for responding. No changes to oil pressure or temp as far as I can tell. Oil pressure was dropping to around 15-20 psi at idle - maybe a little more than usual. No loss or power with throttle. I have a little bit of downhill coming into my neighborhood - I usually put it in neutral and coast to keep the car quiet (Sidepipes with classic chambered inserts- no muffler). When coasting in neutral it was running rough, with low idle and feeling like it was going to stall. It had a bad alternator belt a few months ago, and the charging has seemed off since then. Dimmed lights at idle, brighten when engine speed picks up. I assumed it was a bad alternator or battery. Just have not had time to deal with that yet. The shop that did the head work put in a new - used battery.

 

That thing sounds like a washing machine rolling down a flight of stairs, I can't say I have ever heard an engine that sounded quite like that.
Disconnect the transmission and see if it makes any difference.

 

Funny..., but not. It DOES sound kind of like when our front load washer is out of balance and the tub smacks against the inside of the machine...

 

Well whatever you do don't drive it and don't even run it much til you get someone to listen to it.
"It's getting worse in a hurry" sounds very bad. I suspect something is coming loose and you don't want it to come completely off. Auto or stick? Loose auto flexplate?
Do you have a stethoscope or a long screwdriver to help isolate the noise?.
Dang "quarantine" I'm only 40 miles from you.......

 

Hows the timiing and vacuum look. It could be you jumped a timing gear and its all out of whack. check the basics and see if its still in spec. Drain the oil and cut the oil filter and see if theres any bearing material in there. Its a place to start

 

Yep, sounds like a wash machine out of balance.
Something is broke somewhere.
Not good at all, at least when my engine went it was done making noise in a couple of seconds, then locked up tight. Yours sounds like a gremlin is in there beating with a hammer for you to let it out.

 

That may be it. ...hope so ... if it's an auto trans ... if so, flexplate is cheap to buy & not so difficult to R&R.

 

If it's a stick ... perhaps the center (springs etc) of clutch friction disc has broken apart or (similarly) the pressure plate's spring(s)/diaphragm etc.

-add-
If it's either broken up clutch or flexplate ... regardless ... that shrapnel can (and has) busted & ruined back of block $$$.
Do Not run it.until you've either fixed it or verified it's not that.

 

Would there be a difference then in the sound with the clutch in versus out?

 

Probably

do you have a clutch? yes/no

 

I see he's got a 4spd.

How good are your mechanical skills?
Do you want to talk?
I'll PM you.

 

Thanks again for the replies. My skills are good my tools are limited Myspace even more so. I am working now, but free later on today. Scott

 

I'm thinking "clutch" area... Hope it's not internal the the engine. Check fan and other accessories that run off engine belts.

 

The sound seems to be coming from the back of the engine or down in the clutch area. Definitely not the front of the engine where the fan and all the accessories are. It also seemed to drive just fine, so I'd be surprised if clutch pieces were falling apart. There were no issues going into or out of any gears and no other unusual noises when changing gears. Based on further reading, I'm afraid it may be a connecting rod bearing.

 

rod bearing. when u hit the gas i was sure.

 

That sure sounds like rod knock to me. I would drain the oil and if you see gray or copper color in it which would be the bearing material that is missing. Don't drive it.