For over a year this car used to make a noise that was a mix of a sound of rattling and chattering. It did this at 2 different situations. When coming to a normal stop only when almost fully stopped. If you took your foot of the brake it would go away. AND. When you started taking off from a dead stop. If you took your foot off the gas it would go away. After getting up to speeds around 5 - 10 mph it would be gone. If took off slow it would not make a noise.
It stopped doing this a couple weeks ago. Now itās making a rattling noise coming from the front of the engine. I took the belt off to check all the pulleys. They all are solid.
The exhaust is solid. A friend of mine is picking me up to do some drinking tonight. I believe he has a stethoscope. I will ask him to bring it along to do a quick listen to see if I can better pin point from where itās coming from.
It is very quite when in neutral louder when in gear. Especially is sitting still in gear.
āSolidā may not be the problemā¦ Too close might be. The exhaust moves around when the engine rocks. If the exhaust, especially a heat shield is close to something on the car a rattle can occur.
Putting the car on a lift and shifting through the gears might expose what is touching.
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When it was a couple of years old, my fatherās '63 Plymouth began emitting a strange rattling noise underneath the car when it was idling. Our mechanic found that there was insufficient clearance between the e-brake cable and the exhaust pipe, due to a slight bit of slack in the cable. A simple adjustment eliminated the noise.
Itās a 98. I originally thought exhaust. I drove up the ramps and seen nothing wrong. It was my first thought because this began the second I dropped the gas tank. Having to drop the muffler to get the pipe out of the way.
So then that noise before this was also exhaust perhaps.
As for the heat shield. That has been removed a while ago as it was practically falling off.
Some shops will give a free estimate for a quick check. Iāll have to do that.
A failing bearing if still intact will not effect charging, if you have an impact or high speed drill and you can spin the alt pulley with it somehow, you can hear what the alt sounds like while spinning fastā¦
Like already mentioned by others, spin all your pulleys, but also put some side load pressure on the pulleys while spinning them, to see if they feel roughā¦
The belt tensioner if bad is a little more involved than your normal run of the mill serp belt tensioner (coolant passages)ā¦ But yes a belt and or tensioner can make some noise, especially if the tensioner is jumpingā¦
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The brake relationship you first noted could be an important clue. When stopped in D. brakes on, that puts a significant twisting force on the engine and transmission. If the engine or transmission mounts were beginning to fail, that twisting force could cause something to interfere. Suggest to ask your shop to access the condition of the mounts.
Itās not the exhaust. I put on the ramps and blocked the back tires and put it in gear. With heavy gloves I grabbed the exhaust and nothing took the noise away.
I swapped the tensioner pulley still had the noise. I again removed the belt and the noise was gone. It does get a bit louder when I turn on the air conditioning. Im guessing either that or the alternator. The alternators are different so I canāt swap that.
As for the belt why would they design a belt that a engine mount would need to be removed to change a belt?
In gear at a idle makes it louder and the air conditioner increases it even more. And the noise is continues forever at a idle.
With time the bad pulley should start to show better.
With the rattle the tensioner pulley isnāt the issue. Iāll admit that I havenāt messed with it on a '98 LeSabre, but the rattling issue would be with a weak spring in the auto-tensioner body.