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weird noises driving me nuts

7K views 15 replies 7 participants last post by  Jippi 
#1 · (Edited)
car is a stock 98 c230. the car periodically makes a noise coming from the front right side of the car on the outside. it comes and goes, it mainly happens with a cool engine like when i take off in the morning or after the cars been sitting. it sounds like a blower motor going bad kind of noise coming from the front. it only occurs when im accelerating then let off the accelerator to slow down with out touching the brakes. ive already checked the calipers and they are good, pads and rotors are both new. i inspected the bearings and the such while i had the rotors off and they looked fine and there are no noises coming from it. since i got the car the PO has intermittently gotten a p0410 code for the secondary air system. could it be caused by a bad air pump? also the noise would occur whether the AC is on or off so it isnt the blower motor? i suspect the air pump but before i go buying one can someone confirm that im on the right track?

thanks
 
#2 ·
You need to describe the problem in little more detail. Is the sound coming from inside the dash or from the engine/hood. If it is coming from the engine, check the engine mounts. I had a situation where the front of the car would vibrate and strange sound when first started in the morning. Once the car was warm, it ran fine. The culprits were engine mounts. Do you get any sweet smell when you first start the car in the morning? If so, then it is for sure the engine mounts.
 
#5 ·
grinding noise from the front right side of the car sounds like wither the wheel area or that area under the hood. not from inside the cabin all on the outside. it only occurs when the engine temp is below 60deg and engine speed is round 1.5k rpm. its an 98 no super charger.
 
#6 ·
to cover all the bases while all this occurs the ac is off and windows are down, so it isnt an ac compressor issue. tried unplugging this morning before my drive to work and the connector was siezed on to the pump.
 
#7 ·
wierd noise

The noise is the Air pump "spooling up" It injects air into engine when cool to lower emissions. If it does this when warm, say when city or hiway driving and coming to a stop, then that is wrong. Cold start and until engine warms up is normal. Since Alldata does not show a P0410 code, but does have a P0411 that is for the secondary air pump, the clutch is a good place to start by disconnecting leads at front left connector behind radiator support. They are heavy gauge wires that run independently of the main harness. Lot simpler to disconnect them there than the pump. This will set a code, so be prepared. The other area is the air pump switch over valve. You can find this by following the piping from the air pump. If the pump sounds like a blower fan whistling or spinning up, that is a normal sound, if it is a grinding, grating sound.. that is not normal. Hope this helps!
 
#8 ·
The noise is the Air pump "spooling up" It injects air into engine when cool to lower emissions. If it does this when warm, say when city or hiway driving and coming to a stop, then that is wrong. Cold start and until engine warms up is normal. Since Alldata does not show a P0410 code, but does have a P0411 that is for the secondary air pump, the clutch is a good place to start by disconnecting leads at front left connector behind radiator support. They are heavy gauge wires that run independently of the main harness. Lot simpler to disconnect them there than the pump. This will set a code, so be prepared. The other area is the air pump switch over valve. You can find this by following the piping from the air pump. If the pump sounds like a blower fan whistling or spinning up, that is a normal sound, if it is a grinding, grating sound.. that is not normal. Hope this helps!
thanks this helps alot. now that i know im on the right track instead of just throwing money at parts hoping itll fix it.
 
#9 ·
I have several noises coming from under the hood and am trying to sort them out.

One of them sounds like yours.

My car , 2000 C230K, with about 100m.

This is my son's car and we have only had it a couple of years. I noticed this rattle while accelerating and decelerating but didn't pay too much attention to it until now when the car started having a real hard short rattle at cold start.

The original rattle is there with engine hot or cold. Sounds like a clutch cutting in and out. Occurs at about 1500rpm as you accelerate and if you take your foot off the gas it will do it again. A short 2 second rattle. I have traced this now to the camshaft adjuster magnet, or could be the camshaft itself. If I hold a pry bar on the adjuster and rev the the car I can feel the rattle.

With the hard rattle at start, I suspected the SC, and thought that it might be going and be responsible for both rattles. I've unplugged the SC clutch and the accelerating/decelerating rattle is still there, so it is not the SC. The hard rattle at startup sounded like it was coming from the right side of the engine so I replaced the timing chain tensioner. This required removal of the SC. the bearings of the SC seemed fine, spinning well without any noise.

I'm thinking the camshaft adjuster magnet needs replacing and hope that solves at least one of my problems.
 
#10 · (Edited)
took the air pump out yesterday and it was completely inop so i left it out. took it for a ride before work and the noise still exist the weird thing is that it happens when the engine temp is below 60 deg and engine speed is between 1-1.5k with the car decelerating. there is no noise when accelerating and when the cars in neutral. car needs to be in motion comes from the right side of the enging bay of the car. cant wrap my head around it u would think if its the wheel bearing that it would make noise all the time, if its something to do with the drive belt system it would do it when u rev the motor in neutral. its a long shot but since its temperature dependent could it be a bad duo valve or coolant pump causing it? does the duo valve operate when the hvac is off? when does the coolant pump operate?
 
#11 · (Edited)


we got a vid clip
 
#12 ·
UPDATE: new discovery it started making the noise going down hill so i cut off the motor and noise is still there. i pumped the brakes a few times to make sure nothings stuck so noise is still there. im thinking wheel bearings, but theres no other noises after the car warms up and no vibrations either so what do you guys think?
 
#14 ·
can the wheel bearings be adjusted? theres no shimmy or shake while crusing in the car, but i have noticed that theres a slight humming noise when im cruising down the road coming from the front pass side wheel. im gonna swap the wheel over and rule the tires out before i go and spend money on the wheel bearings, local indy shop quoted an hour of labor plus parts which is comes out to be a total of 400 ish.
 
#15 ·
Sometimes the source of the noise is deceiving so I would check each wheel. First, jack up each wheel and grab the tire at 9 and 3 and see if there is any play. Then remove wheel and spin the hub. It should be obvious if there is a problem.

If they are growling, they are probably damaged and should be redone.

$400 doesn't sound bad if they use quality bearings. You only do this maybe once in the lifetime of the car (assuming about 250m for life of car).

Cheap (URO) front bearings are about $20/wheel. As with any URO part, fine if you don't plan on keeping the car, a waste of money if you plan on keeping the car, cuz you'll be doing this repair again.

If you do it yourself, you face the problem of setting the correct play in the bearings. Procedure requires the use of a dial indicator, something most people don't have.

I did the bearings on my old 1991 300CE and did it just with the "thump" method and they seemed to be OK. The "thump" method is adjusting the bearing tightness and thumping the tire with your fist until you no longer have a vibration.
 
#16 ·
dropped it off at the shop the wheel bearings are fine turns out a loose heat shield got into the drivesaft. they also said the ball joints were bad so waiting to get car back now...
 
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