Engine Rattle Noise?
Posting Guru
Joined: Jun 2009
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From: Wagener, SC
This would be helpful info
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.
I wonder if anyone has more info on this? It would be a great diagnostics tool, and I could use that info myself right away.
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From: Virginia
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.
What you could also do is take all the sparkplug wires loose one at a time on the dist cap, and put them back on loosely. Get the engine running with the noise, and with a glove and some pliers, lift each sparkplug wire off the dist. The engine should start missing and running rough, but what you want to listen for is the noise. If the noise suddenly goes away with one of the cylinders miss-firing, you know it's related to that cylinder. But a noise related to the cylinder will usually have a steady sound to it, not a random type sound.
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I forgot to mention that oil pressure was good. When I thought the rattle was coming from the oil pan I took the dipstick out but the noise didn't change.
I finally got this engine like I wanted. The carburetor is tuned perfect. Oil pressure is good. Cooling is good. The engine starts right up at any temperature with no leaks. The engine runs smooth as glass with no skips or hesitations at all.
Just the irritating rattle at warm idle I can't figure out...
I finally got this engine like I wanted. The carburetor is tuned perfect. Oil pressure is good. Cooling is good. The engine starts right up at any temperature with no leaks. The engine runs smooth as glass with no skips or hesitations at all.
Just the irritating rattle at warm idle I can't figure out...
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From: Denver Metro Area, CO
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I am pretty sure the flexplate is the problem. My uncle mentioned that he thought the starter seemed too loud, like the gears were not engaging correctly, even though it started right up. I thought the noise was coming from the crankshaft; my uncle thought it was in the oil pan, and the starter is very loud. He even mentioned the noise sounded like sheet metal vibrating on something. It all makes sense now.
Is my starter now damaged if the flexplate is damaged? If I replace the flexplate, will I need to replace the starter at the same time?
Is my starter now damaged if the flexplate is damaged? If I replace the flexplate, will I need to replace the starter at the same time?
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Joined: Nov 2007
Posts: 22,415
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From: Denver Metro Area, CO
In general, a rattle will generally come from outside the engine, not inside. Problems
inside generally manifest themselves as some sort of knocking sound, there is really not
much inside of an engine that could make a rattling-sheet-metal sound.
I would take the starter motor to an auto parts store and have it bench tested, see how it
sounds there.
inside generally manifest themselves as some sort of knocking sound, there is really not
much inside of an engine that could make a rattling-sheet-metal sound.
I would take the starter motor to an auto parts store and have it bench tested, see how it
sounds there.
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Joined: May 2010
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From: Richmond, VA
Tagging along with great interest as I'm having a similar problem, though I can't hear mine at idle. Mine starts as soon as the throttle is cracked open, and goes away abruptly if I give it a little more gas. Definitely sounds like a rattle or vibration though as opposed to a knock.
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Joined: Sep 2009
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In general, a rattle will generally come from outside the engine, not inside. Problems
inside generally manifest themselves as some sort of knocking sound, there is really not
much inside of an engine that could make a rattling-sheet-metal sound.
I would take the starter motor to an auto parts store and have it bench tested, see how it
sounds there.
inside generally manifest themselves as some sort of knocking sound, there is really not
much inside of an engine that could make a rattling-sheet-metal sound.
I would take the starter motor to an auto parts store and have it bench tested, see how it
sounds there.
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Joined: Nov 2007
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From: Denver Metro Area, CO
Most likely yes, but I'm suggesting he remove it and take it to a place that tests a lot of
these things, I'm hoping that somewhere along the way something will jump out at
somebody as being the obvious cause of the problem. Simply saying "the motor turns or
doesn't turn" when power is applied isn't really enough IMHO as there is the Bendix stuff
also, the mechanical linkage that connects the electric motor to the flexplate but that
doesn't let the flexplate turn the motor when the engine starts.
these things, I'm hoping that somewhere along the way something will jump out at
somebody as being the obvious cause of the problem. Simply saying "the motor turns or
doesn't turn" when power is applied isn't really enough IMHO as there is the Bendix stuff
also, the mechanical linkage that connects the electric motor to the flexplate but that
doesn't let the flexplate turn the motor when the engine starts.
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From: Harrisburg, PA.
You say the belts and pulleys are fine but did you take the belts off and start the motor? I had a noise that sounded like a rod going. We used the stethoscope, had several people look at it and it sounded like it was coming from the back of the oil pan.
Before tearing into things I thought to take the belts off and start the truck. Turned out while taking the belts off I discovered the water pump shaft had a lot of play. It seemed tight when the belt was on but with the belt off, it was wobbly. You couldn't even tell it with the scope and you couldn't see it when the motor was running.
Before tearing into things I thought to take the belts off and start the truck. Turned out while taking the belts off I discovered the water pump shaft had a lot of play. It seemed tight when the belt was on but with the belt off, it was wobbly. You couldn't even tell it with the scope and you couldn't see it when the motor was running.
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The sound does sound like it is coming from the back of the oil pan.
I started the truck with the belts off, and the "rattle" is still there, ONLY AT IDLE. Give it gas, its goes away. I tried the truck with the belts off, and the rattle is still there.
Since they were old anyway, the water pump was replaced, and the alternator was replaced. I don't have a smog pump or A/C. Still have the rattle.
I started the truck with the belts off, and the "rattle" is still there, ONLY AT IDLE. Give it gas, its goes away. I tried the truck with the belts off, and the rattle is still there.
Since they were old anyway, the water pump was replaced, and the alternator was replaced. I don't have a smog pump or A/C. Still have the rattle.
Posting Guru
Joined: Jun 2009
Posts: 1,509
Likes: 1
From: Wagener, SC
The sound does sound like it is coming from the back of the oil pan.
I started the truck with the belts off, and the "rattle" is still there, ONLY AT IDLE. Give it gas, its goes away. I tried the truck with the belts off, and the rattle is still there.
Since they were old anyway, the water pump was replaced, and the alternator was replaced. I don't have a smog pump or A/C. Still have the rattle.
I started the truck with the belts off, and the "rattle" is still there, ONLY AT IDLE. Give it gas, its goes away. I tried the truck with the belts off, and the rattle is still there.
Since they were old anyway, the water pump was replaced, and the alternator was replaced. I don't have a smog pump or A/C. Still have the rattle.
