'65 200 Rod Knock?

[Eaglo]

Yea, I know it's really silly trying to diagnose engine noises on the Internet, but I'll ask anyway.

I have a '65 (7 bearing) 200 in an Econoline Pickup. Runs great, rebuilt the head last year. It's got the Loadomatic distributor with a Ford 1 bbl, three on the tree, all stock. Since it sits next to me in the Econoline, I hear everything.

Only when it warms up and is being run at about 2500 RPM under light throttle does it make a "brrrrrrr" sound. Nothing metallic, nothing scary. But kind of noisy nonetheless. Doesn't do it when it's cold and doesn't do it when accelerating or when slowing down. Give it a little gas or take your foot off and it stops.

The thing has a tailpipe that just about ends under the cab and an oil bath air cleaner, so the possibilities of here this is originating are endless. I don't think it's an exhaust leak -- the o-ring and manifold are new and tight. The oil pressure's okay. Advance and timing are fine.

Not sure if it did it with the old heads -- there was no exhaust manifold back then. No, I didn't dump antifreeze in the crankcase either.

Probably looking for someone to tell me not to worry -- but I know it's not that easy.

Any thoughts?

Eddie

 

[rbohm]

8) a rod knock will sound like someone is using a small hammer, and double tapping the crank shaft when the engine is running. it will speed up or slow down in conjunction with engine rpm. it will also sound like it is coming from the bottom end of the engine. it will be a sharp tapping sound. a main bearing knock will sound like a dull knocking sound, but not a double tap, again coming from the bottom of the engine and it will also be rpm sensitive. a lifter noise will sound like it is coming from the top of the engine, is rpm sensitive, and is a single tapping sound that happens at half engine rpm. a buzzing sound is normal for these engines, the stock six is quite buzzy sounding especially in a van.

get a stethescope, they are available at your local auto parts store, or at harbor freight for a few dollars. this way you can find out where the noise is coming from.

 

[Eaglo]

Thanks much for your reply and the education on knocks.

One distinction I note with this is that if I rev the engine when it's warmed, I can get it to produce a series of these sounds or even just one or two.

The stethoscope is a good idea. Sitting in the cab of this thing with the engine cover open, you can't hear yourself think, no less concentrate on a single sound.

Thanks again.