Weird engine noise at speed
03-25-2008, 07:19 PM
#1
Weird engine noise at speed
Okay, on my 91 se, I have a strange sound(like a buzzing) in my car. On a nice day, I get into my car and can drive hard (any gear)with no sounds. However, when the engine warms up a little, I get the noise from my car. In first gear, I can rev all the way up to 6k at full throttle with no problems. however in 2nd at full throttle, at about 4-4.5k the engine starts to buzz. if I let off the clutch, the rpms drop and the noise stops. If I ease off the gas(clutch engaged), the sound persists, but is much quieter. In 3rdand 4th it's the same deal, but at about 3.8-4.2k. I haven't gotten it to do it in 5th(I dont drive that fast, usually 3300 tops.) and it also does not do it in neutral. I do not know if its related, but I have a couple of exhaust studs broken, and need to replace the input shaft bearing (short on money, atm...)
What I need to know is what would cause this weird noise. It isnt the normal exhaust "tick," and the engine runs great, asside from this. It does not sound like a rattling exhaust, either. Its more... rough? almost strained. but the intake and the exhaust sound okay. the car feels good too.
also, if anyone can offer suggestions on how to diagnose it, please let me know.
What I need to know is what would cause this weird noise. It isnt the normal exhaust "tick," and the engine runs great, asside from this. It does not sound like a rattling exhaust, either. Its more... rough? almost strained. but the intake and the exhaust sound okay. the car feels good too.
also, if anyone can offer suggestions on how to diagnose it, please let me know.
03-25-2008, 07:29 PM
#5
03-25-2008, 07:35 PM
#6
03-25-2008, 07:50 PM
#8
do you guys have any suggestions on how to diagnos if that may be it?(I do need mounts, but like i said money is tight...) I am more concerned about whether this is or can be fatal to the engine/tranny than just fixing a weird sound. when i have some cash available, i can start working on the other important stuff.
03-25-2008, 09:58 PM
#9
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Well considering an exhaust rattle, or trannsmission related could be the cause, you should probably wait until you R&R the trans and exhaust before worrying about a sound that is more than likely a side effect of the major issues you have going on.
03-26-2008, 04:58 AM
#11
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Give us your noise, so we may diagnoise...
U say warming is one factor.
Q: do your engine mounts warm up?
Q2: What parts do warm up which may have affect?
U say rpm is one factor.
Q. What does change as rpm changes?
Part answers: Air/Exhaust Flow = leaks. Engine Angle = ?. Accessories, Belts...
Solution no.1 ... Start driving like granma, max 2200rpm.
U say warming is one factor.
Q: do your engine mounts warm up?
Q2: What parts do warm up which may have affect?
U say rpm is one factor.
Q. What does change as rpm changes?
Part answers: Air/Exhaust Flow = leaks. Engine Angle = ?. Accessories, Belts...
Solution no.1 ... Start driving like granma, max 2200rpm.
03-26-2008, 05:23 AM
#12
except when i get on the hi-way, i do. ****ing bastards wanna get on at 35-40 mph, while the truckers are doing 70.... i dont wanna die...
03-26-2008, 06:13 AM
#13
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Q: are there no weird sound while stationary, playing with rpm's? If not, the causes are (?) limited to engine angle -effects, horse pwr transmission -route onto asphalt
Hoses etc rubber parts characteristics do change when they become hot.
Last edited by Wiking; 03-26-2008 at 07:08 AM.
03-26-2008, 12:06 PM
#15
03-26-2008, 01:12 PM
#16
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I'd put the fault on some accessory bearing. Take accessory belts out one after another and repeat the test. Waterpump belt should not be out too long...
On the other hand, if that was true, the same sound should be manifested stationary. Hmm.
On the other hand, if that was true, the same sound should be manifested stationary. Hmm.
03-26-2008, 01:24 PM
#17
those both were my thoughts... go ahead and try anyway?
03-26-2008, 01:59 PM
#19
like when you try to start the engine when it running? no i dont think it sounds like that.
the video was about the best i could do with what i have, and aside from the volume of the noise(just a little louder), it sounds about like it does when im driving, at least on my computer speakers.
the video was about the best i could do with what i have, and aside from the volume of the noise(just a little louder), it sounds about like it does when im driving, at least on my computer speakers.
03-26-2008, 05:15 PM
#20
tuck your camera under the cables on top of the tranny and hook the armstrap into the N/R switch harness. then drive with your camera recording while it's under the hood.
and ya i'm serious about that. i did it once and the results are a lot clearer.
and ya i'm serious about that. i did it once and the results are a lot clearer.
03-27-2008, 01:32 AM
#22
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Yes but as the last resort. Easiest tests first. (What are they?)
If it was my car, I would loose sleep until the source was found... (I love company leasing cars as daily drive - sigh. nowhere in sight)
Anyways, like a bearing failure, intermittently resonating...
If you keep pedal steady, will the sound be the same? Or is it limited only into acceleration? How does it respond to accel/decel -'pumping'?
If it was my car, I would loose sleep until the source was found... (I love company leasing cars as daily drive - sigh. nowhere in sight)
Anyways, like a bearing failure, intermittently resonating...
If you keep pedal steady, will the sound be the same? Or is it limited only into acceleration? How does it respond to accel/decel -'pumping'?
03-27-2008, 06:23 AM
#24
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Can you get external microphone (5$ at radioshack), clamp it on tranny etc so that engine noises will be transmitted mechanically directly into it. Then changing mic positions, seeking the source...
03-27-2008, 06:36 AM
#25
if its a bearing, i wonder if a stethascope would reveal this at idle....
brb
edit:
damn, i don't know where my dad's is at, and a screw driver wasnt long enough for water pump and ps pump.
ill swing by autozone later and see if they have one...
brb
edit:
damn, i don't know where my dad's is at, and a screw driver wasnt long enough for water pump and ps pump.
ill swing by autozone later and see if they have one...
Last edited by BenStoked; 03-27-2008 at 06:45 AM.
04-03-2008, 12:23 PM
#27
okay, its been a few days, and i have done some looking at the engine. first, as wiking sugested, and asside from a few busted manifold bolts, everything seems okay.
next, i checked the belt tension on my wp/ps belt, and it seemed a little tight. i loosened it a little, and now i can get the "noise" w/out load. Video here:
it seems to be coming out of the intake (
), which is weird, because there seemed to be a direct link to my loosening of the belt, and the change(is that the right word?) in the sound.(I could be wrong about this, but im pretty sure.and the entire engine is loud at wot...)
next, i checked the belt tension on my wp/ps belt, and it seemed a little tight. i loosened it a little, and now i can get the "noise" w/out load. Video here:
it seems to be coming out of the intake (
), which is weird, because there seemed to be a direct link to my loosening of the belt, and the change(is that the right word?) in the sound.(I could be wrong about this, but im pretty sure.and the entire engine is loud at wot...)
04-03-2008, 05:01 PM
#28
okay, its been a few days, and i have done some looking at the engine. first, as wiking sugested, and asside from a few busted manifold bolts, everything seems okay.
next, i checked the belt tension on my wp/ps belt, and it seemed a little tight. i loosened it a little, and now i can get the "noise" w/out load. Video here:
it seems to be coming out of the intake (), which is weird, because there seemed to be a direct link to my loosening of the belt, and the change(is that the right word?) in the sound.(I could be wrong about this, but im pretty sure.and the entire engine is loud at wot...)
next, i checked the belt tension on my wp/ps belt, and it seemed a little tight. i loosened it a little, and now i can get the "noise" w/out load. Video here:
it seems to be coming out of the intake (
), which is weird, because there seemed to be a direct link to my loosening of the belt, and the change(is that the right word?) in the sound.(I could be wrong about this, but im pretty sure.and the entire engine is loud at wot...)
04-03-2008, 08:39 PM
#30
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Id take off the belts completely just to test out the sound. IE warm the engine up, take off the belts, start and test and then put them back on and test again.
There isn't any power loss is there? Oh and the VG has those butterflys in the intake, I wonder if they are causing something weird. Maybe take off the vac fitting for it and see if that was causing any thing.
I really couldn't think of what it could be to change the intake note so much. I would think its a bad injector failing but its semi predictable so IDK. Id vote for fix the known issues asap and trouble shoot after.
~Alex
There isn't any power loss is there? Oh and the VG has those butterflys in the intake, I wonder if they are causing something weird. Maybe take off the vac fitting for it and see if that was causing any thing.
I really couldn't think of what it could be to change the intake note so much. I would think its a bad injector failing but its semi predictable so IDK. Id vote for fix the known issues asap and trouble shoot after.
~Alex
04-03-2008, 09:03 PM
#31
no, there is no noticeable power loss.
as a side note, the tube between the headlight and filter box had been removed, allowing for a little better sound and a little oomph(butt dyno says "slight power gain") but that is not the cause of the sound, it probably makes it more noticeable
as a side note, the tube between the headlight and filter box had been removed, allowing for a little better sound and a little oomph(butt dyno says "slight power gain") but that is not the cause of the sound, it probably makes it more noticeable
04-04-2008, 01:07 AM
#32
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