1963 Low Pitch Rattle at Front of Motor Runs rough

[Frederick H.]

I drove the car about 40 miles a month ago and it ran smoothly, exhaust clean, etc. It sat for about 4 weeks and now it runs rough with vibration after about 2,500 RPM (will drive again to better monitor). I am hearing a low pitch rattle/rumble? towards front of the motor and noticed both belts show a lot of "chatter" at idle and I can see a slight up and down movement during rotation when looking along the the top of the alternator belt. I plan to remove the belts tomorrow and run to see if I still detect the noise. I checked the points for pitting (nothing excessive) with dwell set to 30 as before - haven't checked the timing yet but nothing changed since last driven. Always something - hopefully it is just the water pump starting to go unless you all have some other thoughts like the harmonic balancer, etc.

Thanks in Advance,
Fred

[Ed S.]

Re: 1963 Low Pitch Rattle at Front of Motor Runs rough

Check your harmonic balancer - it may be coming apart.

[Tom L.]

Re: 1963 Low Pitch Rattle at Front of Motor Runs rough

Take the belts off the water pump and check the bearings. Similar complaint from my brother in law AFTER we went for a run. 50 miles from home he mentioned it. I grabbed the fan and even with the belts on it moved. On the way home, only 4-5 miles out, major failure. Fan went into the radiator. Replacing the pump, fan and radiator is not a fun job. Good luck!

[Duke W.]

Re: 1963 Low Pitch Rattle at Front of Motor Runs rough

If you can wiggle the water pump pulley, even slightly, the bearing is likely goin' south. Usually this will cause the seal to leak before the bearing disintegrates, giving you fair warning, but not always.

Water pump bearings for these vintage cars are standard SAE designs. There are two sizes - 5/8" and 3/4", and both sizes are available in two types - ball/ball and ball/roller.

The first type has two sets of balls and the second type substitutes one set of balls with rollers, and this design is more durable.

The 5/8" ball/ball type was OE on most vintage Corvettes up to the late sixties and as front end accessory loads increased it was switched to the 3/4" type.

Whenever I had a water pump rebuilt (Years ago there was a water pump rebuilder a few miles away from me.) I always specified a ball/roller type replacement bearing.

Duke

[Frederick H.]

Re: 1963 Low Pitch Rattle at Front of Motor Runs rough

Thanks all - yep, hope it's not the balancer. Thanks Duke for the info on the water pump bearings - - very helpful. Will take the belts off tomorrow and note the results. And just while ago the stinking parking light quit blinking - gees - always something with these cars. Keeps us out of the bad places at night I guess .

[Rich G.]

Re: 1963 Low Pitch Rattle at Front of Motor Runs rough

Had this on my 66 327/350. So I replaced the water pump. Then I found the cracked Harmonic Balancer. Look Closely.

Rich

[Frederick H.]

Re: 1963 Low Pitch Rattle at Front of Motor Runs rough

Will do - thanks Rich.

[Patrick H.]

Re: 1963 Low Pitch Rattle at Front of Motor Runs rough

Thankfully the balancer rebuilders have a quick turnaround, should it be that.
Water pumps can be rebuilt as well.

[Frederick H.]

Re: 1963 Low Pitch Rattle at Front of Motor Runs rough

Good to know - thanks Patrick.

[James G.]

Re: 1963 Low Pitch Rattle at Front of Motor Runs rough

Balancer is what I was going to suggest as well.
Thanks for the prompt, I need to send mine out for rebuild.

I thought there was something wrong with my snap on timing light, I couldn't pick up the timing mark on the balancer, nope the balancer had slipped 20 degrees.

[Richard M.]

Re: 1963 Low Pitch Rattle at Front of Motor Runs rough

My Wife's '63 PG 300HP PS, PB SW Coupe developed a awful rattle, rap, clunk at idle. It sounded internal near the front of the engine. No play in water pump. I then checked the harmonic balancer and pulley attachment bolts. I snugged them up a bit. Same problem. Then I decided to lossen the belts and remove the HB pulley and run the engine for a few seconds. Sound gone! Then I looked very closely at the HB pulley.

The pulley mount holes were cracked at 2 positions.

New pulley, noise gone.

Rich