What the H#!! is this noise? Slant six mystery engine sound...

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MN1968Valiant

MN1968Valiant

In College's Stranglehold
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Sep 26, 2009
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Location
Eden Prairie, Minnesota
My car makes this noise intermittently on start-up, and I'm not exactly sure what to make of it. Timing chain? Ideas welcomed.
Motor is stock with 66k miles on it.

I just uploaded the video to YouTube, so it might not be visible yet. Be patient with me 8)

[ame="http://www.youtube.com/watch?v=HvVCdPkpQME"]YouTube- Slant Six (/6) Mystery Engine Noise[/ame]
 
You can use the end of a long screwdriver to touch different parts of the engine while holding the plastic end to your ear to quickly pinpoint the problem.Just be careful of the moving parts.
 
I would check all your bolts to make sure they are tight, pullies, alt, fan etc. Could be a timing chain but it sounds like it runs nice, maybe just starting to go out? Does the sound change when you rev it up? Could it be your power steering pump? Dumb question but is your oil level good? Start basic and don't over look the simple/easy things.
 
Instead of something with a plastic handle, use a long extension. Plastic is an insulator and will distort and muffle the sound. The steel extension will amplify the hound out of it and you'll find it real quick. I've heard alternators make noises like that.
 
66340SEDAN said:
I would check all your bolts to make sure they are tight, pullies, alt, fan etc. Could be a timing chain but it sounds like it runs nice, maybe just starting to go out? Does the sound change when you rev it up? Could it be your power steering pump? Dumb question but is your oil level good? Start basic and don't over look the simple/easy things.
Click to expand...
The noise doesn't seem to be RPM-based to my memory.
As far as bolts go, I'll check the tightness on all the pulley, fan, etc. bolts tomorrow.
Oil level is good, too. I've run it a little low from burning oil before, so I keep better track nowadays.
BubbaCuda said:
You can use the end of a long screwdriver to touch different parts of the engine while holding the plastic end to your ear to quickly pinpoint the problem.Just be careful of the moving parts.
Click to expand...
I have a mechanic's stethoscope and I've tried listening all over the front but can't seem to pinpoint the origin.
mygwenevere66 said:
have you tried running it for a few seconds with the belts removed?
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Running without the belt is a good idea to try, the only bummer is that the noise is intermittent. If I hear it, it happens right off start up. It never suddenly comes on when driving, but it doesn't always come on, either.
StrokerScamp said:
I've heard alternators make noises like that.
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The alternator is new as of spring of this year. Had to put in a two-field after going to electronic ignition and burning my mechanical voltage regulator. So I think that is the one front accessory drive piece I can rely on.
 
I have money on the alternator as your culprit as stated earlier. Just because its new doesn't mean its any good. Take the belt off and spin the alternator with your hand and also see of there is any up and down movement that would indicate a bad bearing. The belt may just be too tight and stressing the bearings. Just my opinion.
 
for what ever reason i had my dip stick hit the crank once or twice everyonce in awhile...
 
Sounds exactly like the problem I had. The flex plate bolts came loose from the crank side, which requires droping the trans.

,Cliff
 
BadAss71 said:
I have money on the alternator as your culprit as stated earlier. Just because its new doesn't mean its any good. Take the belt off and spin the alternator with your hand and also see of there is any up and down movement that would indicate a bad bearing. The belt may just be too tight and stressing the bearings. Just my opinion.
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Well, I took the belts off and spun the alternator. There wasn't any perceivable play in the pulley, so I'm still thinking that's good.
805moparkid said:
for what ever reason i had my dip stick hit the crank once or twice everyonce in awhile...
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Were there any markings on the dipstick to indicate this? I'm not really sure what to make of that possibility since my dipstick looks good.
hellion_locdogg said:
Sounds exactly like the problem I had. The flex plate bolts came loose from the crank side, which requires droping the trans.
,Cliff
Click to expand...
805moparkid said:
oh god i forgot about that! my tq to flex plate bolts loosened up and i thought i killed something
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I'm running an 833OD that I swapped in earlier this summer (and have since rebuilt ](*,)). I torqued the flywheel and pressure plate bolts to spec and used blue loctite on all of them, but how likely would it really be that any bolts backed out? I'd like to not have to do transmission removal number three any time soon.
66aCUDA said:
Boy that REALLY sounds like an Alternator bearing. Second guess would be a piece of sheet metal.
Frank
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As far as the sheet metal comment goes, I'm not really sure what you mean? Something hitting a piece? Or what?

Otherwise, the fan, alternator bolts, etc. are all tight. This is the only other thing I came across...
[ame="http://www.youtube.com/watch?v=_fwXyewlEHw"]http://www.youtube.com/watch?v=_fwXyewlEHw[/ame]
 
Kyle, did you run the car with the belts off? My car made that noise and it WAS the alternator. It had that kind of crackle noise that would not go away. I changed the alternator and its gone. You have three bearings to deal with the water pump, alternator, and p/s. With the belts off you could run a car a few moments without hurting anything and eliminate three possible issues!!
Chas.
 
Kyle
Yes that could cause your noise. Good job on trouble shooting the problem. I may have a good pump if you need one. PM me and I will check.
Frank
 
ChazRam said:
Kyle, did you run the car with the belts off? My car made that noise and it WAS the alternator. It had that kind of crackle noise that would not go away. I changed the alternator and its gone. You have three bearings to deal with the water pump, alternator, and p/s. With the belts off you could run a car a few moments without hurting anything and eliminate three possible issues!!
Chas.
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Chas-I forgot to mention that I did start the car with the belts off. I didn't hear the noise, but I'm not entirely surprised since it is intermittent. While I did have the belts off, though, I hand spun the alternator and found no play in the bearing.
VDART said:
water pump?? Lawrence
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Same as the alternator, Lawrence, I found no play in the pump's bearing when I had the belts removed.
66aCUDA said:
Yes that could cause your noise. Good job on trouble shooting the problem. I may have a good pump if you need one. PM me and I will check.
Frank
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Frank-I'm marinating on what to do about this. I've been debating about going to manual steering, and a bad pump might give me an excuse to start looking for the parts for the swap. If I don't swap, though, a PM will go your way.
Out of curiosity, do you know, by chance, if /6 PS pumps are different from V8 pumps?
 
it looks as if theres a bare metal spot on the pass side inner fender..like the alternater was hitting it and transmitting the then louder alternator.

it does have the typical alternator grind noise, but check for contact at the inner fender.

get a shorter belt.jmo
 
Kyle
Either pump will work. I cant remember if the belt length changes or not. I know you can put a slant pully on the V8 pump. Sometimes the mounts are not the same.
Frank
 
MN1968Valiant said:
Well, I took the belts off and spun the alternator. There wasn't any perceivable play in the pulley, so I'm still thinking that's good.

Were there any markings on the dipstick to indicate this? I'm not really sure what to make of that possibility since my dipstick looks good.


I'm running an 833OD that I swapped in earlier this summer (and have since rebuilt ](*,)). I torqued the flywheel and pressure plate bolts to spec and used blue loctite on all of them, but how likely would it really be that any bolts backed out? I'd like to not have to do transmission removal number three any time soon.

As far as the sheet metal comment goes, I'm not really sure what you mean? Something hitting a piece? Or what?

Otherwise, the fan, alternator bolts, etc. are all tight. This is the only other thing I came across...
http://www.youtube.com/watch?v=_fwXyewlEHw
Click to expand...

That looks to be your problem, I'd say that is it, change it and see what happens.

1wild&crazyguy said:
it looks as if theres a bare metal spot on the pass side inner fender..like the alternater was hitting it and transmitting the then louder alternator.

it does have the typical alternator grind noise, but check for contact at the inner fender.

get a shorter belt.jmo
Click to expand...


I too, noticed that your alternator is way out there and you have little room for belt adjustment, a shorter belt is probably a good idea.
 
StrokerScamp said:
Oh yeah, that just eliminates it from ANY and ALL possibility. LMAO
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Well, all jokes and sarcasm aside, your asinine comment tells me you apparently overlooked my other notable comment about the alternator. I did spin it by hand while I had the belts off, and while it isn't the same as the mechanical load provided by the belt from the crankshaft, I found no perceptible play in the bearing--thus lowering its priority on my list of possible noise sources.

Don't think I'm too stupid to recognize the possibility of a part being broken out of the box. Rather, I used common sense to downplay its likeliness as the noise source since it's the only new pulley on an otherwise-original 40+ year old accessory drive. Thanks A TON for the constructive comment, though.
 
MN1968Valiant said:
Well, all jokes and sarcasm aside, your asinine comment tells me you apparently overlooked my other notable comment about the alternator. I did spin it by hand while I had the belts off, and while it isn't the same as the mechanical load provided by the belt from the crankshaft, I found no perceptible play in the bearing--thus lowering its priority on my list of possible noise sources.

Don't think I'm too stupid to recognize the possibility of a part being broken out of the box. Rather, I used common sense to downplay its likeliness as the noise source since it's the only new pulley on an otherwise-original 40+ year old accessory drive. Thanks A TON for the constructive comment, though.
Click to expand...

why are you taking his light hearted comment personal???

let it go, YOU are the one asking for help...
 
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