Club Cobra - strange sound in engine

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strange sound in engine

hi everyone
where has the time gone. here it is almost june! anyway, been real busy with tennis and cars.
got a question for the small block experts. put a rebuilt roller 302 in my daughters bronco. about 3000 miles on the engine and its developed a slight knocking noise in the engine. the sound is more like that of an exhaust header leak and seems to be coming from the right front of the engine. its not very loud. very difficult to hear when engine is in park. in drive under load the noise seems to get louder. sound doesn't seem to be coming form the valve train. drained the oil thru a filter and found no metal or debries. checked the oil and there was no trace of metal or coloring that might indicate a spun bearing. checked end play on crank and was within tolerances. checked distributor gear and it looked normal, no sharp edges. she's visiting over the weekend and i'd like to fix the problem before she has to leave. help!!!!!!!
thanks,
paul
ps several engine people have listened to the engine and agree it doesn't sound like a rod bearing or wrist pin, especially since there is no metal or color in the oil. i really don't want to pull the engine and disassemble. a

Paul,

If it is a mechanical fuel pump, I had the same noise. I thought it was a light rod knock or valve train problem. I traced it down to the arm on the fuel pump. Just a thought!

Larry

A fuel pump issue would be heard on the driver's side. It's very possible that she has an exhaust leak. I've heard some pretty nasty ones. You might wanna pull the valve covers and make sure that there's no slack in the valvetrain.

thanks brent and larry
the engine has an electric fuel pump. as much as i hate the idea of disassembling the engine i guess that will be the next step. the intake plenum covers the right side valve cover. typical. guess we'll start with removing the intake so we can look at the valve train. if anyone else has any ideas, give me a holler.
thanks,
paul

I would recommend picking up or borrowing a device I've used in the past. Basically, it is a cheap doctors stethascope (sp) with the listen end taken off and a hollow , thin copper rod braze or slipped into the single tube line in it's place , about 2 feet long, The idea is to place it on the block, near suspected areas to listen for source of noise. Bearing or wrist pin issues are easy to hear as you rev the engine. Can also be done with an old fashioned 2 plus foot long screwdriver with a wooded handle...tip on block, ear on handle.

Hey Paul, I'd check the header gasket first. If you could spring the header/exhaust manifold out far enough from the head to see if there's any signs of exhaust leaking. It will be obvious.

Harbour Freight sells the engine stethoscope pretty cheap and it works pretty good.
Also, any metal rod or bar will transmit a surprising amount of noise (touch one end to the engine where you suspect the problem and hold your ear close to the other end). Try a breaking bar or some rebar. Good luck.

lazy lifter ?

It was still there after the oil change?