Engine Rattle Noise?
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Engine Rattle Noise?
I have a mysterious "rattle" noise coming from my 302. The noise is only heard at idle (750RPM) and goes away if the engine is revved up. It sounds like it is coming from the crankshaft pulley. It's not loose and doesn't appear to be damaged. However, the A/C system has been completely removed, including the belt that goes around the pulley. Could that be causing the noise?
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From: Virginia
Take the pulley off and check the condition of the rubber and the outer ring that has the timing marks on the damper(the part the pulley bolts to). The outer ring that has the timing marks on it is only connected to the center hub by rubber. If the rubber gets old, it can loosen up.
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From: Suffolk, VA USA
You don't really need the puller if you're just taking off the pulley to check the condition of the damper. Just remove the belts and the 4 small bolts, and then give it a light tap with a rubber hammer. You will need it to pull the damper if it needs changing...
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From: Suffolk, VA USA
You have to loosen the belts up top, but with the 302 there's room to do the job from underneath without pulling anything else.
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If it's REALLY bad, it may even be visible from the top, too. I've seen some Chevy dampers where the wheel has slipped 1/4" away from the center.
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From: Virginia
I suppose it could be the timing chain rattling against the timing cover. You can take the dist cap off, and watch the rotor as you turn the engine over by hand. Turn the engine in one direction till the rotor moves, then turn the engine the other way till the rotor moves again. Take note how much the lower pulley turned before the rotor turned the other direction.
I say all this, but I am not sure how much is too much movement. Maybe someone else knows or you can find it on the web. If the chain has a lot of slop, the pulley will move an excessive amount before the rotor turns when you change direction.
I say all this, but I am not sure how much is too much movement. Maybe someone else knows or you can find it on the web. If the chain has a lot of slop, the pulley will move an excessive amount before the rotor turns when you change direction.
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The only belts I have are the alternator belt and he water pump/power steering belt. And it's neither one of those. The air conditioning belt has been removed. Would a pulley without a belt around it be making a noise like this?
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From: Sheffield, AL
Rick,
Make a mark across the face of the harmonic balancer with a crayon or chaulk, with the engine off, then drive a while. If the rubber to metal bond is failing, the line will shift such that it no longer is straight.
If your truck has a manual transmission, and the harmonic balancer is failing, the squeak or noise heard at low RPMs sometimes will change pitch as you depress the clutch.
Also, the noise is likely more pronounced when the temperature is lower [hard rubber is more likely to slide].
Make a mark across the face of the harmonic balancer with a crayon or chaulk, with the engine off, then drive a while. If the rubber to metal bond is failing, the line will shift such that it no longer is straight.
If your truck has a manual transmission, and the harmonic balancer is failing, the squeak or noise heard at low RPMs sometimes will change pitch as you depress the clutch.
Also, the noise is likely more pronounced when the temperature is lower [hard rubber is more likely to slide].
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My uncle and I (an old school mechanic) spent 4 hours checking over my whole engine yesterday. My uncle said that is doesn't sound like the top end, and although he did notice a very slight wobble, he said the harmonic balancer looks ok. We have eliminated the following:
- belts and pulleys are fine
- water pump is good
- power steering pump is good
- alternator is good
- torque converter bolts are all tight (I discovered my dust shield was missing)
- starter bolts are tight
- crank bolt is tight
- I tried turning the crank pulley, but it was too tight to turn by hand
With the engine running, I got under my truck and got a good listen, and the noise seems to be concentrated in the oil pan or where the transmission bolts to the engine. The odd thing is, when the engine has cooled off a bit and I start it again, the noise is greatly reduced. As the engine warms up, the noise gets louder and more irritating. Again, the noise is heard at idle and goes away when I give it gas.
It sounds like a hollow rattle, almost like a loose bolt or baffle was sitting inside the oil pan and was vibrating inside of it. What in the world could that be? We checked every nut and bolt in the area, but could not find anything loose.
- belts and pulleys are fine
- water pump is good
- power steering pump is good
- alternator is good
- torque converter bolts are all tight (I discovered my dust shield was missing)
- starter bolts are tight
- crank bolt is tight
- I tried turning the crank pulley, but it was too tight to turn by hand
With the engine running, I got under my truck and got a good listen, and the noise seems to be concentrated in the oil pan or where the transmission bolts to the engine. The odd thing is, when the engine has cooled off a bit and I start it again, the noise is greatly reduced. As the engine warms up, the noise gets louder and more irritating. Again, the noise is heard at idle and goes away when I give it gas.
It sounds like a hollow rattle, almost like a loose bolt or baffle was sitting inside the oil pan and was vibrating inside of it. What in the world could that be? We checked every nut and bolt in the area, but could not find anything loose.