Author Topic: weird whirling sound (Read 4778 times)

AL GReeNeRy · « **on:** November 15, 2006, 06:58:18 AM »

i recently took out my rear seats to do a subwoofer installation. ive been driving around without the seats for a few days now and ive been hearing some loud sounds when im accelerating and when i let off the throttle.. the first sound is most noticeable when i am doin 80+ and i try to accelerate. it sounds like a loud whirling/whistling sound. ive narrowed it down and i think it can be:

a) exhaust leak- i am SURE i have an exhaust leak, sputters when i accelerate and i have a broken bolt that connects to the center section (another set of headers is on the way)
b) differential- changing out to redline fluid by this week regardless so it might quiet it down a bit
or
c) fuel pump.

the next sound is when i let off the throttle.. its like a humming sound that changes with pitch (comes from the rear of the car), sounds similar to the noise when a person is on a dyno and they let off the gas; however, the sound varies with engine speed. any help would be appreciated. thanks.

biljak · « **Reply #1 on:** November 15, 2006, 07:25:50 AM »

have you properly grounded your amplifier? is it increasing or decreasing pitch with the engine revs? is this sound present when the amps are turned off?

Alpine003 · « **Reply #2 on:** November 15, 2006, 12:49:48 PM »

The first sounds like a fuel pump. The second could be a few things but also double check your wheel bearings.

johna · « **Reply #3 on:** November 15, 2006, 04:24:17 PM »

If you can hear it all the time (over the engine) at a constant speed then it's probably the fuel pump. If it changes with engine speed it's probably your differential.

AL GReeNeRy · « **Reply #4 on:** November 16, 2006, 05:52:30 AM »

the sound occurred before i put the subwoofer/amp in and i know EXACTLY which sound youre talkin bout, and its not that type. i was studying the sound again, and when i am exactly at 80, everything sounds normal. but once i try to accelerate past 80, i hear the whining sound. as for the second part where i let off the throttle, lets say i am in second accelerating between 20-25 and i let off the gas; the engine sorta bogs down kinda like a mixture between the afm and clutch and the sound happens simultaeously with the bog down, but it comes from the rear.

AL GReeNeRy · « **Reply #5 on:** November 17, 2006, 07:48:48 AM »

UPDATE: so the first sound turned out to be the fuel pump. i felt the vibrations where the cover for the fuel pump is and its definitely it. so the question is now, should i juss replace it with a stock replacement or is there something i can upgrade to?

johna · « **Reply #6 on:** November 17, 2006, 06:13:29 PM »

It is normal that they are noisy but if it is unusually noisy it may be a sign that it is close to the end of its life. Personally I would run it until it fails. When it does fail it will usually stop the car from starting but you can encourage the fuel pump to work by hitting the fuel tank hard whilst starting the engine (either from underneath the car below where the pump is; or, lift the rear seat and hit the edges of the top of the fuel pump cover; or, hit the are below the rear seat foam near the fuel pump area).

AL GReeNeRy · « **Reply #7 on:** November 18, 2006, 12:12:38 AM »

well that is what i am trying to avoid, i commute daily from san francisco to fremont and i cannot risk gettin stranded. the pump is unusually loud and it happens on and off. one day itll be loud, the next it wont be AS loud but it will be noticeable. my question still stands, should i replace it with an OEM one? at autohausaz.com a new fuel pump costs about $200 is there any other one cheaper? mayeb a 255lph? got a future swap in mind so a 255 wont be so outragous

individualist · « **Reply #8 on:** November 18, 2006, 07:36:38 AM »

May want to pick one up before it fails. Mine went out on my way home from work as I was pulling into town at the first stop light. Worst traffic of the day and the light turns green and I push the go pedal and the car lanches 10 feet and dies. Now I'm in the intersection with what seemed like a thousand cars zipping all around me. I'm lucky I have a good battery and starter cuz that's what I used to propell me to safety, up hill about a hundred yards to a gas station. Called my son and we towed home from there. Not very fun at the time.

AL GReeNeRy · « **Reply #9 on:** November 18, 2006, 08:42:23 AM »

Quote from: individualist;14019

May want to pick one up before it fails. Mine went out on my way home from work as I was pulling into town at the first stop light. Worst traffic of the day and the light turns green and I push the go pedal and the car lanches 10 feet and dies. Now I'm in the intersection with what seemed like a thousand cars zipping all around me. I'm lucky I have a good battery and starter cuz that's what I used to propell me to safety, up hill about a hundred yards to a gas station. Called my son and we towed home from there. Not very fun at the time.

thanks for the info, thats exactly what i dont need. now any know what to get thats cheaper than an OEM for $200+shipping?

individualist · « **Reply #10 on:** November 18, 2006, 06:46:11 PM »

I bought one out of a salvage yard for $40. It has worked great for the past 6months, real quiet compared to the previous pump. I had sticker shock when I priced new ones so I just got the used and bought a new fuel filter and changed them both out and was back on the road in about 45 minutes.

AL GReeNeRy · « **Reply #11 on:** November 18, 2006, 07:22:42 PM »

Quote from: individualist;14038

I bought one out of a salvage yard for $40. It has worked great for the past 6months, real quiet compared to the previous pump. I had sticker shock when I priced new ones so I just got the used and bought a new fuel filter and changed them both out and was back on the road in about 45 minutes.

know EXACTLY where i can get a used one, would the 325e/i pumps work the same?

individualist · « **Reply #12 on:** November 18, 2006, 09:54:56 PM »

Not sure on the 325e/i pump? What year is the 325? I can do a search for corresponding part numbers. Mine came out of a 91 318i.

AL GReeNeRy · « **Reply #13 on:** November 19, 2006, 12:31:16 AM »

ive seen many aluminum bumpered e30s so 85-87

individualist · « **Reply #14 on:** November 19, 2006, 10:37:08 AM »

Don't think a pump from those cars will work. Part numbers are different and I don't believe the 325's put out the same pressure from the pump. The tank numbers are the same so it would probably fit correctly but might be a fuel pressure problem with that pump. See if you can locate a 318 series in your area that's being parted or a salvage yard may have one.