buzzing engine noise. Help!
 

Hello, I started to hear a buzzing sound, I think was the belt tensioner or any accesory (water pump, alternator,..) bearing of the belt, I checked all of them and the belt and is OK. I haven't discovered where side the noise come, I only hear inside the engine.

What do you think is?

you can see a video I've recorded:

http://www.youtube.com/watch?v=p85bzy-3Mjg

remove the belt then start the motor for a short time while listening. if noise is gone shut motor off and feel all the pulleys for play

^--- what he said. Definitely sounds like an accessory -- my bet is alt. Don't run the engine for more than 30 sec without the belt... But you probably knew that already.

I started the motor without the belt, but the noise still go on.

try unscrewing oil fill cap while engine is making noise

Why should I try this? if I remove the oil fill cap, the noise dissapear and why?

Unfortunately at the moment is impossible to try this, because I have doing the IMS upgrade, and the gear box and clutch is out of the engine. But I want to take advantage of this dissasembly to give a solution to this noise.

some of te sounds people report from the AOS going bad are ...well a little odd

so, if the problem came from de AOS when I try to unscrew oil fill cap, what happend with it? it's hard to remove or what? thanks.

have you talked this noise over with the people that are working on your motor ?

No, I'm doing by myself. I've got mechanical title :)

I'will check the AOS.

Do a search ....
 

Search using the word AOS then find the post called " Is my AOS going?" Scroll down and read the posting by 944boy. His post sounds very much like what you describe.

Good luck,

J T

Sorry I don't know how to copy the link to someone else's posting for you.

This sound he described is a vacuum sound, it's different that mine.

When a AOS goes bad or starts to go bad you may have a different warning sounds. The most common is smoke coming out of the engine when running. Mine made a whistle like screetch when the engine warmed up. The vacuum that is being pulled can suck air around the crankshaft seal. So, if you cannot remove the oil filler cap when the engine is running then the AOS is going bad. Was this noise there before you started doing the engine maintenance, if so, then you did not cause the problem. Not sure if you are suppose to run a flat 6 with the flywheel off.

i wanna see him start it with the flywheel off...does yours have a pull start

this noise appeared, 2 das before I start to do the maintenance.

Is possible this noise come from the start engine?

Get a stethoscope from the auto store, remove the belt and listen for the sound around the crankshaft seal and listen to the timing chains. How many miles the Box.

it has got around 90000 miles.
Now I'm changin the IMS bearing, so the chain are loose, how can I check it? should I check the chain tensioner, too?

pull the oil sump and cut open your oil filter....tell us what colors you find and the size of the stuff

sorry I don't undestand very well you what you want to tell me. can you explain me? do you want to open de oil filter to see what color is? I emptied the oil, but I've got the old oil keep in a bottle.

Sorry but my english sometimes is not perfect. thanks.

do you know anyone in your area that knows engines made by PO that can help you ?

I usually posted in my country porsche forum, but nobody know what the noise come from. I posted in this forum because I know there is a lot of boxster experts.

I guess I need to open the oil sump to see what colour is inside, it's ok?

I will try to open the sump an take a photo.

heiwaz,
extanker was refering to opening up your old oil filter (cut the ends off), unfolding the paper element and inspecting to see if there are any metal or plastic particles lodged in the element.
Metal could = IMS bearing wearing.
Black plastic could = IMS bearing plastic shield breaking up.
Red / brown plastic could = chain tensioner guide wear.
If you do find any of the above, the next sensible step is to remove the bottom of the sump to see just how much debris is in there. These results will give you some idea on how to procede next...
Hope this helps - your English is far better than my Spanish too....

thank you very much Steve Tinker, this help me a lot. Now, I've got the IMS bearing cover removed, so I can see the bearing plastic shield and it's in perfect condition. I will open the oil filter to see any plastic or metal particles. Thanks!

Today I remove the oil filter an inspect the paper and I only found in the exterior side this smalls particles of plastic, but is a Soft plastic. The only particle hard is the one of the bottom right, the others are soft.

http://img217.imageshack.us/img217/280/imgp1408.jpg

Looks something like soft gasket material, at least there are no metal specks, but.....
If it was me, the next step would be to remove the sump (oil pan) and inspect the debris laying in the bottom. Not a difficult job +/- 16/18 bolts.

Ok, I will do it tomorrow, but do you know if the sump has got gasket, and if it need to be replaced once is open?. thanks

Your IMS bearing may not look bad from under the cover but the inside seal could have failed allowing oil to wash out the grease in the bearing. Was there any kind of oil leaking from the bearing?

I have removed the IMS bearing to install the LNE, and the old bearing was in good condition.

I've removed the oil sump and the only things I found is the same gasket particles. This particles came from the sump gasket.


http://img405.imageshack.us/img405/4520/imgp1429d.jpg




Otherwise, I discovered that one chain tensioner is harder than the other when you push it. I start a new post whith this issue:

http://986forum.com/forums/showthread.php?t=26941





.

I think, finally find the problem of the buzzing noise.

I removed the spark plugs, and found in the spark tube (1) ans stranger particle non metallic, I hit with a hammer and it broke in 3 pieces. I believe is a little stone and it done a vibration doing the noise. Do you think is it possible?
In this spark tube had an oil leak inside, too.

http://img148.imageshack.us/img148/9752/imgp1436a.jpg