Buzzing noise from front of motor.

[shawn w]

I have been noticing lately that i get a noticeable buzzing sound from the front of my motor. Does it when cold but does it more when warmed up. It does not do it at idle, but starts at about 1500 RPM's. If i put my hand on the valve cover i can feel a little vibration when it starts buzzing. The car still seems to run and drive fine though. Could anyone please tell me what is wrong with it. At first i thought it might be some of the tensioner pulley going bad, since it has kind of a bad bearing sound but now i am not so sure. The belts never squeak. It just this buzzing whirring noise. I am thinking it may be somethinb timming chain/vanos related.

Thanks,
Shawn

[cheddafob]

does it do it more prominently when the revs drop through around 1500-2000 rpm? or even when u are holding at that rpm in gear? Mine does it too...I think it might be the fan blades slightly hitting something. Is it coming from inside the motor or from outside?

[shawn w]

Yeah it does kind of make it a little bit lounder when revving the rpms are coming down. Yeah and it starts at around 1500-2000 rpm's

Thanks,
Shawn

[zcasavant]

I'm getting EXACTLY the same noise.

[JamesM3M5]

Could be the idler and tensioner pullies rattling due to dry bearings. I replaced both tensioners and all 3 idler pullies last weekend, and the noise is all gone. Sounded like a buzz or fast rattle when revving up or down. The bearings in all of them were shot, and the tensioners didn't have the fluid-damping effect the new ones do. Have all the parts needed if you're interested, too.

[ChewToy]

I would like to purchase the parts mentioned above. Could you check and see if you can extend the "free shipping" to a board buddy?

[////\/\ark]

This may be a stupid question... but what are the idler pulleys and where are they located?

I may be interested in purchasing a secondary chain tensioner along with the 3 idler pulleys from you (I have already replaced the primary tensioner). My car has had this buzzing/whirring for quite some time now, and I'm tired of it.

Also, how long would this job take a mechanic? I'm not so sure that I'm confident in doing this sort of engine work, so I want to see if it would be fiscally realistic for me to take it to an independent shop.

[shawn w]

so you guys think it is more the idler pullies than timming components? I too figured it was probably the idler pullies at first but now i am not so sure. It soo hard to tell where it is coming from.

Thanks,
Shawn

[Mantic]

so you guys think it is more the idler pullies than timming components? I too figured it was probably the idler pullies at first but now i am not so sure. It soo hard to tell where it is coming from.

Thanks,
Shawn

If you're feeling a vibration on the front of you valve cover when the noise starts i don't think it has anything to do with your pulleys. Sounds more like a vanos problem to me.

[rfc2307]

Time to head on over to Home Depot for a 3 foot piece of hose, the old engine stethescope.

If the noise can be isolated from the metal front cap on the top of the E36 valve cover, it is most likewise a VANOS issue.

You should be able to isolate the noise to the exact part with the garden hose trick.


Then open the Bently Manual

[aweather]

Time to head on over to Home Depot for a 3 foot piece of hose, the old engine stethescope.

If the noise can be isolated from the metal front cap on the top of the E36 valve cover, it is most likewise a VANOS issue.

You should be able to isolate the noise to the exact part with the garden hose trick.


Then open the Bently Manual

Yes rfc2307 had the right idea, start there. I have a similar noise that is being described and I diagnosed it as the secondary timing chain slapping around. When I get some money I am going to replace the secondary timing chain, tensioner, guide rail, and both cam gears. I am still undecided on whether or not I'm going to screw with the VANOS as I don't think it's the problem but it does have 100K miles on it so I might just do it for preventative maintinence. Oh and I might replace the primary tensioner as well. There are several good threads on this subject that I read through of different peoples experiences, what worked and what didn't so do a search.

Hope that helps
Alex

[////\/\ark]

My buzzing is definitely coming from the timing chain cover. Not only can you feel a sort of tapping on it when you rev the engine, but it also gets unbelievably hot after the engine runs for a while. This may be normal for all I know, but man... it gets *hot*.

So I'm assuming that since these idler pulleys aren't in that area (are they??), I probably need to change out my secondary tensioner. Perhaps I need to go as far as changing the actual chains and chain guides. Does anyone know how long it would take a mechanic to replace these parts?

[ChewToy]

Well I have my own thread running but I'll repost the contents here because it seems like we're all dealing with the same issue...

Ok guys I need your help because the search feature isn 't enough info and I'm leaving for vacation soon and need to have the car fixed before then... I'm pressed for time.

I have a 95 M3 with 79k miles on it. It's an autox / weekend car and I've recently developed a noise from idle to roughly 2k rpm. It's going to sound familiar to some of those on the board... facing the motor with it running it's coming from the top of the motor closest to you near the vanos unit. Giving it some gas you can feel and hear what I describe as the chain hitting up on the cover. This is just my guess. I had something similar to this happen 4 years ago and they replaced the Timing chain tensioner, exhaust cam gear and crank gear. I thought I would have to do that again. Well I just took it to an independent BMW mechanic and he tells me he thinks it's the VANOS unit. I told him what they repaired last time and he still thinks it's the VANOS. He clearly saw on my face that I didn't agree with him so he says, "I tell you what I'll put a new VANOS unit on the car and if it doesn't fix it I'll take it back off." So I say whatelse can you ask for and agreed to go that route. What do you guys think about this? Does this sound like a VANOS issue to you?

I can really hear the noise during take off's.. and then after 2k rpm the noise goes away.. either that or it's getting drowned out by exhaust noise and I can't hear it anymore.

What would you guys do in my shoes? Let him replace the VANOS and see what happens? He says once he has the valve cover off he can check the tension on the chain etc... I'm guessing this will give him more clues as to what is going on ... right??

How many of you have had similar problems with the S50 M3 motor and what did you have to replace to get it fixed?

Lastly what is a reasonable cost to have the VANOS unit installed?

Thanks everyone for reading... any input appreciated.

[Seeker]

This is getting interesting.

Tonight I noticed the same sound you guys are talking about. I have a 1993 E36 w/2.5L engine 164Kmiles. Has a clunking sound coming from the top of the top timing cover that is in front of the valve cover.

Be interesting what you guys find.

[r6jon]

I have a '97 M3 with 114k miles and it makes the same noise when the engine is decelerating freely through 2k rpm. It sounds from inside the car like a card in the spokes of a bycycle sound : I'd almost like to say that it does sound like something rubbing the fan shroud - but the clutch fan makes me think not because it's too "connected" to rpms. Anyway, I'm sure there's someone out there who has solved this problem if it's so darn common. I just hope they stumble onto this thread! I have yet to listen under the hood, hopefully when I do my waterpump this week I'll have time to hunt for the strange noise.

[Bav///Man]

Let him replace it and see what happens. If you don't need a new unit, the noise will persist, but if you do you will isolate it.

My question is, is this a normal symptom of a little bit of an older VANOS unit, or is it really bad?

Well I have my own thread running but I'll repost the contents here because it seems like we're all dealing with the same issue...

Ok guys I need your help because the search feature isn 't enough info and I'm leaving for vacation soon and need to have the car fixed before then... I'm pressed for time.

I have a 95 M3 with 79k miles on it. It's an autox / weekend car and I've recently developed a noise from idle to roughly 2k rpm. It's going to sound familiar to some of those on the board... facing the motor with it running it's coming from the top of the motor closest to you near the vanos unit. Giving it some gas you can feel and hear what I describe as the chain hitting up on the cover. This is just my guess. I had something similar to this happen 4 years ago and they replaced the Timing chain tensioner, exhaust cam gear and crank gear. I thought I would have to do that again. Well I just took it to an independent BMW mechanic and he tells me he thinks it's the VANOS unit. I told him what they repaired last time and he still thinks it's the VANOS. He clearly saw on my face that I didn't agree with him so he says, "I tell you what I'll put a new VANOS unit on the car and if it doesn't fix it I'll take it back off." So I say whatelse can you ask for and agreed to go that route. What do you guys think about this? Does this sound like a VANOS issue to you?

I can really hear the noise during take off's.. and then after 2k rpm the noise goes away.. either that or it's getting drowned out by exhaust noise and I can't hear it anymore.

What would you guys do in my shoes? Let him replace the VANOS and see what happens? He says once he has the valve cover off he can check the tension on the chain etc... I'm guessing this will give him more clues as to what is going on ... right??

How many of you have had similar problems with the S50 M3 motor and what did you have to replace to get it fixed?

Lastly what is a reasonable cost to have the VANOS unit installed?

Thanks everyone for reading... any input appreciated.

[a_slew_of_mice]

I was cleaning my engine earlier and noticed that I'm getting the same noise coming from the VANOS area. It sounds like something is rubbing underneath the silver part of the valve cover. I would be interested to know if ChewToy has any updates on his situations.

[a_slew_of_mice]

bump for more information

[blown330]

so , what was the result of this discussion? anybody figure out the problem

[Stuntman]

Any new information on this? I have the same problem

[////\/\ark]

My particular noise was pretty much fixed (though the engine still isn't perfectly quiet). The following thread discusses what I did to get it fixed:

http://forums.bimmerforums.com/forum...36#post3172936

Mine are posts #8 and #10. Hope this helps a bit.

[RagnarDanskjold]

Likewise, in other threads I've been contending that the issue is related to the primary timing chain elongating over time.


I've replaced everything up top except the actual camshafts, and I've also replaced the primary tensioner, and I still get that buzzing louder than ever from the front of the engine.

It sounds and feels like it's coming from the VANOS unit, but I beleive most assumptions about bad/noisy VANOS units are erroneous. Once you've pulled one apart and seen how it all fits together, you'll see that it's a fairly simple piston which wouldn't make the buzzsaw noise.

If I put my ear right by the front of the valve cover, Id've sworn it was the VANOS unit. HOWEVER, just this morning, I did the same but listened to the area just below it behind the lower timing cover, and I could trace its source to that point. This is precisely where the primary timing chain runs past the guides and would flop.

I had the front of the car apart and *almost* had the lower timing cover off, but I was thwarted by the 22mm bolt that holds the balancer and main pulley on the front of the crankshaft. That must come off for the lower cover to be removed.

I'm regrouping, and in 2 weeks will be going back in and showing no mercy until I've put the new chain in and retimed the cams.

I'll be photographing the entire procedure (film, alas. no digital) and doing a writeup of the procedure to complement the one I did for camshafts and VANOS. I will photograph and measure the new chain and the old side by side for comparison, and obviously report on whether or not it resolves the noise issue.

Anyone in the KC area is welcome to bring lawn chairs and beer, and to cheer or jeer as they deem fit.