My Six Cylinder out of '59 Chevy was jst recently rebuild (crankshaft been ground, new main and rod bearings, bored, new pistons and rings, head and blocks has been resurfaced, new camshaft, new valve shafts and vave seats reground, new hydraulic lifters and pushrods, new rocker arms, new oil pump, everything has been done!). It just runs perfect. However, at cold starting, there is a serious ratteling, which disappears after about 2-3miles when the engine warms up. I never experiencend it driving around down town. But after two hours doing about 75 on the Interstate, the rattel noise came back. I stopped at a gas station and it really sounded like something was broken. I cut it off, got gas, payed and fired it back up and the ratteling was gone. The engine was runnig as smooth as*****er and the noise was gone. What is going on in my engine? What causes this kind of problems?
Got an idea, could it be the harmonic balancer/pulley getting loose. Had a 235 in an old truck and the pulley got really loose and finally wore through the rivets holding the pulley to the balancer. Got another one, and the junkyard welded the rivets to the pulley and no more issues. Check it out.
You might want to take a stethascope or even use a long screwdriver (put your ear on the handle) and listen to various points on the engine to try to narrow down where the rattle is coming from, that would be a big help towards trying to come up with what the problem might be.
sounds like the balancer coming loose. this happened to mine. drill a hole in the front of the crank and tap it, and bolt the balancer to the crank and see if that does the trick
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