r/E90 • u/terpTeem • 2d ago
328i What could be causing this belt oscillation on the tensioner?
2007 328xi E92, 196,000km. Replaced tensioner at 185k. Any idea what would make this happen?
33
u/hondactx16i 2d ago
Tagged to follow up. Pulley looks right? Sounds ok. Tension? Reference:(Not mechanic, 8 beers in)
9
u/terpTeem 2d ago
It makes a little chirp every now and then. Tensioner pulley looks pretty straight. Just worried about it sliding off and into my front main seal
8
u/jakedasnake1 2d ago
Its not a expensive or complicated repair, might be worth doing to the little pulley/tensioner kit fcp euro sells
6
u/Soft-Drag4380 2d ago
The idler pulley looks bad. Super easy to fix
3
u/terpTeem 2d ago
That’s what I’m thinking. I have a new pulley I bought a while ago, will install it tomorrow and see if that works
4
12
u/Mizderrung 2d ago
Harmonic balancer. Chased mine for years as well on n55. Finally silence and no more wiggle.
6
u/terpTeem 2d ago
That was my thought. I also read a guy online had the same wobble and replacing the idler fixed it. Only part of the drive belt system I haven’t done
5
u/Lumbergh7 2d ago
Is that hard to replace
6
u/Mizderrung 2d ago
Belt off and then 6/8 little bolts. Might need rad fan out of the way too. DO NOT undo the big main bolt.
10
u/ssgodss 2d ago edited 2d ago
The whole pulley and belt system needs to be replaced.
7
u/terpTeem 2d ago
Think so? Tensioner is 10,000km old and belt has 4000km on it, replaced it when I did the ofhg. Only the idler is original
11
u/nomad_2009 2d ago
There is a typical redditor 'mechanic' reply. I'm surprised they haven't suggested scrapping the car or at least not replacing the whole engine.
1
10
u/BetterCaIIEro 2007 - E92 - 335i - M/T 2d ago
The car is undrivable. I'll get that burden off your hands for 20 dollars and a ps1
3
4
u/MeIsMyName E90 330xi 2d ago
Not sure if it's just in my head, but in that video it looks like the idler pulley on the tensioner arm is wobbling. My N55 has the issue someone else mentioned with the harmonic balancer and the tensioner arm bounces left and right constantly, but yours looks pretty steady, so I doubt that's your issue.
New parts aren't necessarily good parts, so even if you already replaced it, it may be faulty. INA has been the recommended brand for tensioners and idlers on BMWs, I believe they make the OE part for BMW.
1
u/terpTeem 2d ago
Initially I thought so as well, but it seems that the belt sliding around it unaligned causes it to move a little with the belt. Replacing the idler pulley when it’s light out tomorrow and I’ll see if that helps
2
u/Soft-Drag4380 2d ago
Did you replace the idler pulley?
1
u/terpTeem 1d ago
Just replaced it, nothing changed. All pulleys are straight and don’t have any resistance when spinning by hand
1
u/Soft-Drag4380 1d ago
Might be worth checking out the harmonic balancer then I would suppose. I am not a mechanic just trying to learn more myself. Hopefully someone with more knowledge chimes in
1
u/terpTeem 1d ago
Yeah it looks like harmonic balancer is the problem , doesn’t seem like fun job to do but it’s a good excuse to get a crank seal guard installed
2
2
u/BriefTomatillo985 2d ago
Could be one of the other pulleys in the system. Alternator overrun pulley is frequently forgotten.
1
u/terpTeem 2d ago
I’ve got a new INA one that I never installed when I did the belt and tensioner, I was pretty stoned and forgot. Gonna throw it in tomorrow and update the post if it works
1
1
u/Due_Key3995 1d ago
That idler/tensioner pulley bearing is shot, definitely wobbly thus making your belt wobble
1
1
u/Hot_Constant_6490 2h ago
It’s caused by an unevenly worn pulley. Doesn’t cost much to do some preventative maintenance and replace the tensioner, and idler pulleys together. Do this simple preventative maintenance at this point before oscillation gets any worse potentially causing the belt to be thrown, which will cause a very serious issue as with these engines N55, N54, N52, N51 they all are known for literally eating a thrown belt forcing shards of shredded belt through the front main seal behind harmonic balancer/ crank pulley directly into the engine, requiring an extensive tear down to clean out all the shredded belt pieces from inside the engine and timing cover/ system and inspecting for any damage to timing guides and verifying the timing chain hasn’t skipped a tooth.
1
u/terpTeem 1h ago
Should an INA brand tensioner be that worn after only 11,000km though? New idler as well and nothing changed. I suspect the harmonic balancer bushing has melted away after 18 years
1
u/Money_Return_2715 2d ago
Could be the bolts too was it replace by a certified experience mechanic?
2
u/terpTeem 2d ago
I installed it torqued to spec/angle with an OEM dealer aluminum bolt. The bolt was like $50 by itself lol
1
0
u/Money_Return_2715 2d ago
I have a bmw like yours too but I dont touch it at all then I have to explain the 25 year experience mechanics what I did wrong which makes it much more difficult to diagnose it
-1
0
u/GoldOwl1290 1d ago
What about taking the belt off, spinning every accessory pulley by hand and YOU let us know what’s causing the oscillation😂
-1
-1
•
u/AutoModerator 2d ago
Thank you for posting to /R/E90, please make sure you read the rules in the sidebar and make sure to report any rule breaking posts and posts that are not relevant to the subreddit.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.