[lowrydr310]

I own two E9Xs now (E90 330i N52 and E93 335i N54) both with around 160K miles and had a 325i N52 with 260K miles that I gave to a family member (but I still maintain it.) None of these cars ever had a belt break or mess up the crank seal.

I'm in the middle of replacing the serpentine belt on my 335i along with the tensioner and pulleys, and have lots of space to work now. I'm wondering if it's worth installing one of the billet crank pulley seal guards now since I have easy access to work on it.

One one hand I like the peace of mind in case something happens, but on the other hand I've had three of these cars with lots of miles without this protector and never had an issue.

[mecheng77]

Unless you let and ignore oil dripping on the belt, I don’t think so

[HondaRC51]

I agree with Mecheng. If you take good care of your vehicles than I wouldn't bother. I don't think its needed however it is more of a CYA type of thing. "Better safe than sorry" or "better to have it and not need it, than need it and not have it" come to mind.

[CTinline-six]

I take good care of my vehicles, always fix oil leaks quickly, and pop the hood once a week just to check everything.

With that said I added one to both my 328i and a friend's 2006 325i. Reason being is these cars are getting older, and even if you maintain them failures can still happen, and parts quality these days is garbage. I buy all OEM parts, and went through two different tensioners before I found one that didn't have a bad bearing rattle.

A friend's E91 had the belt jump off the pulleys without warning when the A/C compressor pulley just sheared off on the highway. Luckily she shut the car off right away and no damage was done, but it is one of those things where if it does get sucked behind the seal it's a huge PITA. If you can't do the work yourself it will be expensive. It is cheap insurance in my opinion, just like the aluminum mickey mouse flange upgrade.

[SWFLf10]

If you’ve got the money and currently have the access to install it, I would install it. While I also mantain my vehicles, there’s always the chance of something going wrong. Like the AC compressor failing catastrophically as mentioned above. Cheap insurance for the unknowns that life throws at you.

[Cloverdale]

What's stopping you from doing it?

[StradaRedlands]

Checking in w/ another AC compressor incident... shredded the belt but luckily nothing was ingested through the seal.

[whyzee125]

IMO it's a decent failsafe but should be used as an extra layer of protection and not the first. Keep your belt and OFHG in good condition and it's very unlikely you will ever shred a belt, but like the above said, it can happen. Some early models had a subframe that could allow the PS pulley to contact the subframe under certain extreme loads with worn engine mounts. AC compressor could lock up, etc.

[TheMidnightNarwhal]

Kind of in the same dilemma considering like others mentioned you can get failure from other sources than a poorly maintained car. But I'm still thinking if I shut off the car if it were to happen should be good but yeahh.

The other thing that also threw me off getting one was that some people companied the guard made the pulley rub or something. Has anyone had experience with a good guard and can recommend one that works fine?

[Brian86]

The guard is aluminum. Pully is steel.

If it rubs, it'll just, you know, self-clearance.

Don't really think they are necessary. I put one on because I have an original AC compressor (works great) at bonkers high milage. Some concern about it the compressor locking up or failing but can't bring myself to swap out a perfectly good AC compressor.

[bimmerfan1972]

I installed the one from Kies and it rattled so much that I ended up removing it. Messed with it first to make sure it was installed correctly but couldn't solve it.

[thatllbe2000bucks]

Why wouldn’t you add it? It’s a rather cheap part and makes you more calm knowing that out of a 100 issues you only have 99 left. Not absolutely necessary, but not a bad investment. And mine doesn’t rattle.

[StradaRedlands]

What are the no-rattle brand recomendations?

[thatllbe2000bucks]

Originally Posted by StradaRedlands

What are the no-rattle brand recomendations?

I run the ml performance one and it works fine. My friend has an aliexpress one and it works fine as well. If I would have to buy it again I would probably go with the China one. As someone above also stated that even if it rubs a little it will get sanded down.

[thatllbe2000bucks]

To follow up. I dug around aliexpress and found a few for 25€ + shipping. That’s almost 3 times cheaper than us/eu made. Reviews seem good as well. I think it’s worth checking out

[StradaRedlands]

Here's an AE one mentioned in another posting on the merits of Al vs. SS bolts: https://www.aliexpress.us/item/3256805024355514.html

Same one at Bezos' Emporium & Sundries:
https://www.amazon.com/NICECNC-Serpe.../dp/B0BB5H6LZG

[mecheng77]

Wait, AC pulleys fail catostraphically?
I didn’t know that, I’ve only heard of the PS pulley on N54 rubbing, once the engine mounts fail

[thatllbe2000bucks]

Originally Posted by mecheng77

Wait, AC pulleys fail catostraphically?
I didn’t know that, I’ve only heard of the PS pulley on N54 rubbing, once the engine mounts fail

They don’t. He probably meant the power steering pulley. Pulley meets the subframe and it’s game over. Can’t imagine how ac pulley could hit subframe.

[StradaRedlands]

The AC compressor seizes up and throws the belt. Mine made some noises but I semi-ignored them and put off figuring out the problem. I was about 200ft from the mechanic's shop when it let go :-(

[CTinline-six]

Originally Posted by thatllbe2000bucks

They don’t. He probably meant the power steering pulley. Pulley meets the subframe and it’s game over. Can’t imagine how ac pulley could hit subframe.

The PS pulley hits the subframe on the N54 cars.

On the N52/N51 at least the AC compressor can seize causing the pulley to shear off, which is what happened to my friend's E91 at about 130k miles.

*usually* there is a knocking sound from the compressor first, but there definitely was not any sound out of this one.

[oVeRdOsE.]

imo, if you are in a situation to do it ''while I'm there'' , do it, if not, just check your car periodically.


I'm getting the engine out , so I have a list ''while I'm there'' , this included a 20$ plate, 2k$ clutch and a 7k$ single turbo

[lowrydr310]

I installed one of the cheap ones, fit perfectly and seems to not have any clearance issues.

I used the included steel bolts with no loctite, now I'm second guessing myself. Is loctite really needed? Original bolts I removed were aluminum, the ones in the kit were steel.