Not sure what just happened...

[Zooted_plus]

Just put on an edelbrock carb and fired up the engine. Fast idle was on so it was idling around 3k, I shut it off, fire it back up and now it sounds like there's something bouncing around in my engine. It increases when I rev the engine.

I'm almost positive nothing fell in the intake. I hope this isn't a bottom end or a bearing problem. Looks as though I might have to drop the oil pan.

 

[Demonic]

Eeek, that doesn't sound good. It's never a good idea to have a engine running at high RPM while the tranny is not engaged.

How long did you have it running at this high rpm? It sounds to me like a similar sympton I had in my old 72 firebird.

Basically it was a clicking/knocking type sound that ended up being a thrown rod bearing in the first cylinder. Course the engine was very old as it was, so I rebuilt the entire thing rather than just replace the piston rod bearings.

Others call it the "death knock".

 

[65 A Code]

Does it sound like someone is in the engine hitting it with a hammer? IF so you just might have thrown a rod bearing like Demonic said. Before taking the oil pan off, drain the oil and strain it somehow (through something like screen material or something of the sort) and look for metal shavings. When I threw a rod bearing in a 4 cyl that I had, oil had a good bit of peaces of chewed up metal from the bearing in it.
Just a thought.

 

[Zooted_plus]

hopefully its something not too bad but now I am afraid to start it up again.
The fast idle was on, probably about 2500 or so... but I revved it to maybe 3, 3.5 only because I wanted to see throttle response.. I heard no noise then.

I shut it down after running maybe a minute. When I re-started I heard the noise... which sounds like a nut or bolt rattling around inside the engine.

I hope its not the 'death knock'...


Oh well, the engine made about 40 years and 110K miles. The last 30K of which were pretty hard miles as well. Thats pretty commendable in my book.

 

[Demonic]

Hum, it doesn't seem like its a rod bearing then. It doesn't sound like a bolt rattleing around, its a destinctive knock that goes off everytime the piston makes a rotation.

Did you look under the valve covers? It could be something to do with the rocker arms.

At any rate, 110k miles is alot on a engine that prolly had it's fair share of high stress.

 

[D.Hearne]

Sounds to me like a bolt fell into the intake, whether you think so or not.

 

[pabear89]

Check your front balancer, sometimes the rubber comes out from between the inner and outer rings, it will make some starnge noises.


Pb

 

[Zooted_plus]

Ok, just took off the driver's side valve cover, put each cyl to tdc, pulled the plugs and fished around inside the cylinders with a magnet.... Nothing.

All of the valves were there, no broken springs or dropped valves...

Also checked the balancer, the rubber ring is intact.

To be more specific on the sound it's making-- yeah it could be compared to a hammering noise coming from inside the engine. It's a metallic knocking noise, which is echoing through my tri y headers. Its pretty loud.

One thing I did notice when turning the motor over by hand it was very tight in a few spots, almost felt like it was seized... I have a bad feeling it is bearings. Normally it turns very easily.

So what does everyone think.. should I pull the 289, re-ring it, all new bearings, maybe have the crank turned, maybe have the machine shop balance the assembly, valve job, etc, etc... or should I get a 5.0 or a 5.8 shortblock and some aluminum heads?

 

[D.Hearne]

I'd at least pull the heads and intake and see if there's any "extra" parts on the piston tops before pulling the motor. If somethings binding, I'll bet money on a loose bolt on a piston top, before I'd say it's a bearing problem. If it's a bearing, then the binding would be there all the time. You may think you've done a thorough job of "fishing" for stray bolts thru the spark plug hole, but it's damn near impossible to reach to all the corners of the cylinder thru that tiny hole. More likely, the bolt was jammed between the piston top and the bottom side of the head when you fished for it. If anything roll the crank to TDC on each cylinder, then back it off TDC a little ways, then fish for the bolt. Good luck.

 

[Zooted_plus]

I kind of figured that I was only getting a certain radius of the cyl/ combustion chamber...on the #3 cyl I could barely get the magnet tool in the spark plug hole, let alone move it around much. Its hard to pinpoint the noise to a certain cyl.

Honestly I've been kind of waiting for something to happen to the stock engine so I'd have an excuse to get a 5.0, crate engine or shortblock. If I do pull the heads I need new valves, seats, etc... and I might as well pull the whole motor and freshen everything up. Or replace with a known good part.