NoTransistors

The noise is intermittent. Been there for years. Sounds like a rod bearing, but not nearly as loud.
Never at idle. Hold the gas pedal, and you may sometimes hear it. I cannot hear it while holding the throttle from outside, but do hear it inside; seems to be coming through whatever holes are in floor around the cable grommets under the auto shift lever. Logically, a bearing noise is more constant. Weeks and months can go by w/o a peep. Oil guage is its normal wierd self. The 700-R4- if there was an issue, it also would not wait until summer. Torque converter bolts are tight.

Noise was absent ALL WINTER AND SPRING. JUST CAME BACK LAST WEEK.

I actually thought that it might be a loose something in the original mufflers. Also, just pulled the air pump. Car is quieter, but noise still there. If alternator, bearings would be dry by now. Water pump would not be seasonal. Is there a diaphram-based valve of sorts on the engine that controls something or other? There are no leaks at the top of the Y-pipe, or at the heat-riser valve and diaphram. The heat-stove door is also not a suspect. I have no more ideas.

What the heck am I hearing?

Please help. Ask questions, if necessary. Thanks.

Seth

TMX

I've had the same type of noise in my 84 since I bought it ten years ago. Similar to a rod bearing but not nearly as pronounced, comes and goes seemingly at will, and doesn't come in until about 1100-1200 rpm or so. The only difference is that mine only acts up when it's cold out, and then just until the engine warms up. Drove me nuts trying to figure out.

While researching the problem eons ago, I came upon a TSB released by Chevrolet sometime in the 80s which ascribes the noise to (working from memory here) a fuel pump pushrod that was manufactured out of tolerance. The fix was to replace it. The TSB was for 1983 model year carbureted 305s.

This may or may not be what's going on with your motor, but it sounds awful familiar....

-Bob

NoTransistors

Bob,

You still have that vehicle, and your wording indicates that you have yet to repair the issue. What gives?

If this is the solution, then I love you. (Purely in a heterosexual way).

Seth

NoTransistors

Bob,

Just to get your attention so you can answer my question, I am posting to my post , to get it back to the top of the page.

Thanks,

Seth

TMX

Hey,

Here's the short reason why I never fixed it:

I was nearing the end of an eighteen-year run as a professional mechanic at the time, and couldn't stand the sight of a wrench during my off hours anymore. Since the fuel pump pushrod wasn't critical (ie; it wouldn't leave me stranded), I decided to live with it.

Now that I've been retired from wrenching cars for a few years and am starting to get my enthusiasm back for doing this as a hobby again, the motor is coming out anyway, so there's no reason to mess with the FP pushrod at this point.

Sorry I don't have a more definitive answer for you.

-B

NoTransistors

Bob,

I'll take your initial post at face value. The catalog from Summit should be here soon. They have the rod.

Thank You

Seth