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Old 05-10-2015, 01:49 AM   #1
traxnox
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Question Unexplained rattle from engine bay

Hey guys so here's the story, for the past few months my 02 330xi has been making a rattling sound that appears to be coming from under the hood. I did check the DISA valve and it's Nice and tight. So it's definitely not that, I looked around for some loose heat shielding all the heat shielding seems to be fasten down nicely. There's nothing hitting the fan or anything, in that if you hold the fan down and stop it from spinning it'll keep rattling. But it is really strange, sometimes when it's idling it won't rattle, And other times it will. When you start accelerating the rattling stops until you start coasting again. Even if you set the cruise control to say 40 with the windows down you can still hear it. Just can't figure it out for the life of me. Guys have any ideas? Thanks
heres a link to a video i just took of the sound.
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Old 05-10-2015, 03:20 AM   #2
tristero
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My uneducated guess would be VANOS.

However, (manual-only) it's worth it to see if the noise comes and goes when you press down and release the clutch pedal (gearshift in neutral). Specifically, goes away with clutch pedal down, comes back with clutch pedal up. THAT noise might be a loose DMF, which is on the verge of failure (which will take your clutch out when it goes).

You can get a cheap mechanic's stethoscope for less than $10 at most auto parts stores, and that can help to pinpoint rattles like these.
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Old 05-10-2015, 03:25 AM   #3
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It's a automatic! Lol. But I'll google around to see what that vanos is. Not familiar with what that is. Then again, coming from all American cars I don't know what or why half the stuff is needed in these cars. Lol. Just like that DISA valve, I couldn't believe that even existed until I pulled it out, then just had to sit and think of why on earth it was so nesasary to put a $400 mini plastic TB in the intake manifold lol. But Thanks for the tip!
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Old 05-19-2015, 04:06 PM   #4
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Ok, so here's an update. I removed everything... Took both belts off, air intake, checked the DISA again, with no luck. Sound still is coming out the top of the engine. Any more ideas I can check?
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Old 05-19-2015, 05:06 PM   #5
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DISA is necessary; well, maybe not. It changes the length of the intake depending on engine load and RPM, which improves the engine's breathing. This improves overall power, and maybe emissions. Pretty cool idea, actually. However, what's unnecessary is the crappy hinge-pin that comes loose and falls out into the intake, destroying valves and engines.

It's sounding more and more like VANOS;
Vanos is a BMW system for altering the valve-timing. It actually does the job of EGR (Exhaust gas recycling), so no EGR is needed on these cars. (and VANOS does this job MUCH better than EGR systems on most other cars). And that's just a side-benefit of VANOS. The main benefit is that the valve-train cams are on a piston that moves axially and advances intake valve and exhaust valve timing (so that they open sooner in the stroke, at higher RPM). This also improves the engine's breathing - it's almost like a turbo charger - only the benefit is going to be somewhere less than 20 HP. It's really an amazing and ingenious technology. Only; once again, BMW has chosen poor materials. There are a set of seals on the axial pistons, (near the top and front of the motor), and these seals are notorious for wearing out - as early as 15k miles.

These seals are replaceable with a kit from "Beisan Systems" - for under $100. It's not a trivial job, but it's not huge either. The replacement seals are a higher-grade material, and are not known to wear out.

The main symptom of worn VANOS seals is that under load, usually in 3rd, 4th, gear or higher, right at 2800 RPM (accelerating) (and often, uphill), you'll feel the engine sort of "stutter". I feel it in my seat. Even passengers will feel it. A secondary symptom is (on some cars, with the m52 engine), the car will stumble and stall-out while the motor is warming up. A third, more advanced symptom (which is really a separate problem), is a rattle from the VANOS pistons. This is right at the very front of the motor, on top, below the line of the black-plastic valve cover. For this issue, you'd also need the VANOS "anti-rattle kit" from Beisan.

Another option is to contact Dr. VANOS, and buy a new unit for your car. You can send your old unit back for a core-charge refund. I think, in total, this will cost less than $150 if you do the labor yourself.

A third option is to go to the BMW dealer, and they'll charge you about $800; and their unit will have the older seals, which will wear out in 15k miles.

That said: this is all just guessing on my part, because I have limited information. But this is kind of a typical problem with this car. There are tons of threads on how to diagnose and fix this problem all over e46fanatics and bimmerfest.

There are other issues that could cause this kind of symptom. loose valve guides, bad lifters, bent valves. All of those basically mean: "new cylinder head". And it's not as common.
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Old 05-19-2015, 06:03 PM   #6
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Quote:
Originally Posted by tristero View Post
DISA is necessary; well, maybe not. It changes the length of the intake depending on engine load and RPM, which improves the engine's breathing. This improves overall power, and maybe emissions. Pretty cool idea, actually. However, what's unnecessary is the crappy hinge-pin that comes loose and falls out into the intake, destroying valves and engines.

It's sounding more and more like VANOS;
Vanos is a BMW system for altering the valve-timing. It actually does the job of EGR (Exhaust gas recycling), so no EGR is needed on these cars. (and VANOS does this job MUCH better than EGR systems on most other cars). And that's just a side-benefit of VANOS. The main benefit is that the valve-train cams are on a piston that moves axially and advances intake valve and exhaust valve timing (so that they open sooner in the stroke, at higher RPM). This also improves the engine's breathing - it's almost like a turbo charger - only the benefit is going to be somewhere less than 20 HP. It's really an amazing and ingenious technology. Only; once again, BMW has chosen poor materials. There are a set of seals on the axial pistons, (near the top and front of the motor), and these seals are notorious for wearing out - as early as 15k miles.

These seals are replaceable with a kit from "Beisan Systems" - for under $100. It's not a trivial job, but it's not huge either. The replacement seals are a higher-grade material, and are not known to wear out.

The main symptom of worn VANOS seals is that under load, usually in 3rd, 4th, gear or higher, right at 2800 RPM (accelerating) (and often, uphill), you'll feel the engine sort of "stutter". I feel it in my seat. Even passengers will feel it. A secondary symptom is (on some cars, with the m52 engine), the car will stumble and stall-out while the motor is warming up. A third, more advanced symptom (which is really a separate problem), is a rattle from the VANOS pistons. This is right at the very front of the motor, on top, below the line of the black-plastic valve cover. For this issue, you'd also need the VANOS "anti-rattle kit" from Beisan.

Another option is to contact Dr. VANOS, and buy a new unit for your car. You can send your old unit back for a core-charge refund. I think, in total, this will cost less than $150 if you do the labor yourself.

A third option is to go to the BMW dealer, and they'll charge you about $800; and their unit will have the older seals, which will wear out in 15k miles.

That said: this is all just guessing on my part, because I have limited information. But this is kind of a typical problem with this car. There are tons of threads on how to diagnose and fix this problem all over e46fanatics and bimmerfest.

There are other issues that could cause this kind of symptom. loose valve guides, bad lifters, bent valves. All of those basically mean: "new cylinder head". And it's not as common.
Well I can get you any information you really need if you like. The rattling is coming from the top of the engine for sure. I used a listening tool and if you put it on the intake manifold you can hear the sound clearly. in fact, if you put your ear on the intake manifold you can hear it just resonating through from the engine somewhere. what part of the engine should I put the probe on to hear the vanos?
It rattles at 700-800 rpm, not usually under 700. And then stops u till about 1200 and rattles until 1400. Regardless if idling or driving. And regardless of what gear your in. (I have a auto, saying in manual mode)
The car has about 208k on it. There are no heat shields or exhaust shields rattling at all. Nothing up front it lose. It's coming out of that engine. Just can't figure out from where.
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Old 05-19-2015, 06:07 PM   #7
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Sorry guys, I fixed the link to the video on the first post
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Old 06-08-2015, 02:48 PM   #8
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I've got the same thing in my 325ci
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Old 06-08-2015, 08:19 PM   #9
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+1 big time on VANOS and trying Besian seals. This rattle definitely sounds like that.
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Old 06-08-2015, 08:32 PM   #10
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Yeah if it is the vanos do the seals and the bearings. The bearings come in what's called the "anti rattle" kit and a rattle in the vanos, from what I know, makes a very similar sound to this.

Amazing the things I have learned on this forum in the past 2 months about the e46. The first thing I did when I got the car and found this site was engross myself in reading and learning every single thing I could. Multiple times at that. I suggest that everyone should do the same. It's why you see me answering more questions than asking.
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Old 06-08-2015, 09:00 PM   #11
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There might be a few threads where the VANOS was the problem. Other than that, most "mysterious noise" threads go unanswered/no solution given. I'm doing a limited overhaul over the next couple months, (already one month and $1000 into it) and I'll be doing my VANOS regardless. BTW I'm getting the same noise on my '04 325Ci.
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Old 06-08-2015, 11:26 PM   #12
e46addictseba
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The noise doesn't seem to come from the location of the VANOS. It seems to come from the intake manifold
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Old 06-09-2015, 01:07 AM   #13
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Rattlesnake maybe? Okay, just kidding there.

The stethoscope should allow you to pinpoint exactly the source of the noise. You probe around listening for where it is louder and fainter. Start pulling off covers and stuff until you find it.

Make sure the DISA pin didn't fall off into your IM.
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Old 07-18-2015, 09:33 PM   #14
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If it's not too late to comment, it could be a water pump bearing
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Old 07-18-2015, 10:53 PM   #15
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Originally Posted by Platipuss08 View Post
If it's not too late to comment, it could be a water pump bearing

Just replaced mine 2 weeks ago thinking the same thing. Didn't get rid of the ticking/rattling.
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Old 07-18-2015, 11:07 PM   #16
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Just go to Harbor Freight Tools and get this cheapo mechanics stethoscope for $4. It works very well to track down the source of engine noises. I use mine a lot.
http://t.harborfreight.com/mechanics...ope-69913.html
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Old 07-18-2015, 11:55 PM   #17
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Have a similar noise, haven't checked to see if it has gone anyway as I just did my VANOS seals last week. Didn't see much improvement in performance after installing new VANOS seals. And the seals kit is nowhere near $100 lol.
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Old 07-29-2015, 12:34 PM   #18
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Well after much time tinkering with it, I finally fixed it. The timing chain tensioners were shot. Put new ones in and no more rattle. Thanks everyone for the ideas
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Old 07-29-2015, 01:03 PM   #19
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Good stuff!! How did you determine the tensioners were the problem
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Old 07-29-2015, 03:22 PM   #20
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Well, after using a $200 stethoscope for about half hour I got absolutely nowhere. The sound was coming straight out of the intake manifold but no luck finding it. So I said screw fancy crap and just used my ear, opened up the oil cap and listened, sounded familiar, Almost like a lose chain on a bike hitting the frame. So I pulled the valve cover off and pushed on the top tensioner, very very lose, like maybe 2 lbs of resistance. And the lower one was way worse. The piston was just fried like no other.
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