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-   -   Weird problem, new one for me (http://www.genmay.com/showthread.php?t=825005)

[H]ard|On 01-07-2010 02:26 PM

Weird problem, new one for me
 
I pulled in the garage, the other day and left the car running while i went to grab something. Heard a weird noise. Popped the hood, it sounded like an exhaust leak and it was on the side where the exhaust is. Thump thump thump thump... I played around with the throttle, listened real well... "Please don't be a rod bearing or something!"

Went online and found a couple youtube videos on random m3/e36 forums with that same noise. People's guesses ranged from rods to VANOS to everything else. In each case, there was at least one guy who would ask if the plugs had been done recently and suggested one or two being loose. In each case the OP eventually updated the thread saying it was indeed a loose plug (or two in one cae)

I checked mine, bingo. #5 cylinder turned freely by hand and the plug well coil pack tube smelled like gas/oil/exhaust... Tightened it up, voila noise is gone. Turns out this is a common problem on certain BMWs. Mostly because, I'm guessing here, people like me change their plugs and having no torque spec just go real gingerly and carefully not to strip the soft aluminum threads. Then the expansion properties of aluminum and the high-RPM nature of these motors do the rest.

I didn't know this could happen. I've changed plugs many times and never had one come loose. I always thought if it does it'll eventually back itself out enough to strip the remaining few threads and fire out of there like a small rocket or something :o Turns out all that happens is some extra noise and the car runs rough a little bit. So, there ya go. Next time you have a friend with a strange exhaust leak noise it could be a plug that's come out!

Dongboy 01-07-2010 02:28 PM

if only my noisy throwout bearing noise was that :(

Bluesultan 01-07-2010 02:29 PM

[QUOTE='[H]ard|On;24111191']I didn't know this could happen. I've changed plugs many times and never had one come loose. I always thought if it does it'll eventually back itself out enough to strip the remaining few threads and fire out of there like a small rocket or something :o Turns out all that happens is some extra noise and the car runs rough a little bit. So, there ya go. Next time you have a friend with a strange exhaust leak noise it could be a plug that's come out![/QUOTE]

on some engines, like the 5.4L supercharged Lightning motors, they do shoot out a plug :(

glad to hear that didn't happen to you.

[H]ard|On 01-07-2010 02:33 PM

I don't know how long it's been like that. I'm pretty anal and notice most small things but that day I did some serious automotoring and wondered why the engine isn't flawlessly smooth :D

I didn't check all the plugs because i was in a hurry after I found my loose one, so I packed up some sockets to take with me if it happens again on another one and I need to make a quick repair at a gas station or something :)

[H]ard|On 01-07-2010 02:39 PM

ps. tong, does it stop when you put the clutch in?

Probably time for a new clutch anyway NBD :)

Dongboy 01-07-2010 03:07 PM

[QUOTE='[H]ard|On;24111210']ps. tong, does it stop when you put the clutch in?

Probably time for a new clutch anyway NBD :)[/QUOTE]

yea, it goes away when the clutch is in and is only intermittent, sometimes it's pretty soft sometimes it's pretty loud, I just don't want to drop the tranny :lol:

[H]ard|On 01-07-2010 03:11 PM

TO in my integra rattled, it was weird.. normally they whine

I take it out of gear at stoplights and generally whenever i can, this spares the TO bearing the extra revolutions.

Thermo1223 01-07-2010 03:15 PM

The Saturn had 3/4 plugs loose from the previous owner. Now considering he had receipts for all maintenance done I think it was a shops fault.

I always chalked up the super strong gas smell on a cold start to being TBI and old. I finally figured it out when the idle really went to hell one day and I could see one plug twitch on the power stroke. It basically looked like someone was tapping at it.

:lol: Still got 35mpg though

Rancidpunk666 01-07-2010 03:53 PM

torque to 30nm. it's on the spark plug box.

also change your valve cover gasket.

if you can afford a bmw you can afford a touqre wrench.

[H]ard|On 01-07-2010 04:18 PM

[QUOTE=Rancidpunk666;24111431]torque to 30nm. it's on the spark plug box.

also change your valve cover gasket.

if you can afford a bmw you can afford a touqre wrench.[/QUOTE]

keekles. vcg, I'll get that when I do the vanos. it isn't leaking right now so what's the point?

torque ratchets - I have two.. at my parents house. :(

Also the last part isn't true. What if I spent all my money on the BMW and pieces for it? See, didn't think of that did ya. :lol:

[H]ard|On 01-07-2010 04:20 PM

ps. damn thermo. did you get the feeling that the rubber boots were holding them in?

and what do you mean TBI :wtf: I thought all saturns were dohc mpfi etc and it was GM's Honda Killa

Typhoon43 01-07-2010 04:50 PM

That's better than ford Did in the 99-2001 heads on the 5.4's where the plug holes only had 4 threads. People in F150's and Expeditions would be driving and it would literally SHOOT the plug into the hood , taking the coil pack with it. The Lightnings, cince they were boosted, were even worse. Guys ont he Lightning boards are constantly launchingthem unless they tighten them every oil change. Ford got smart in mid 01' and did 8-thread heads. Those stay put :D

[H]ard|On 01-07-2010 05:37 PM

FOUR threads?

:wtf: :confused:

Did they take a special, stumpy spark plug or something?

grjr 01-08-2010 02:38 AM

Depending on what type of seat the plug has you can just tighten it a certain fraction of a turn after it bottoms out (sort of like oil filters). Easy to do if you don't have a torque wrench. (I am too lazy to google it right now, I'll let someone else do it)

zoopnazi 01-08-2010 05:51 AM

My old dirtbike was kind of like that. If it started to run a little funky, sometimes it meant the spark plug was coming loose :lol:


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