Timing chain guide slide rail broke at tip

cahme · 04-19-2019, 10:56 AM

My car: '11 335i (although this part is same for all E90 non-M)
Mileage: 168k mi

My Valvetronic motor is no longer working, so I pulled the VC and found the tip of the "slide rail" broken off. I'm looking to get opinions as to what could have caused it? I did struggle a bit with getting the VC off, but don't see how that could have caught on the VC and I broke it then?

My plan is to replace this top slide rail piece along with the chain tensioner and I do have the cam timing tool, so that won't be a big deal.

I've attached a pic with the broken one (left) alongside of it from 2.5 years ago (right) not broken.

Gamb1t · 04-20-2019, 01:39 PM

Guess my question is what happened to that plastic shrapnel? And what long term damage it'll cause?
Causes could be material fatigue overtime being beaten by a jump chain? How's the chain tensioner?

Boland01 · 04-21-2019, 07:11 AM

On our old E36 the plastic chain guides broke into small pieces. They then proceeded to clog up the oil pump screen. Noticed it when the oil pressure dropped. Worst case it can do some serious damage. That car had 125k back then when it happened.

cahme · 04-21-2019, 10:12 AM

I did have some small "bits" in my oil that were not silver from my last oil change. I could see them in bottom of oil drain pan, but not feel them rubbing between two fingers. My OPG was also leaking, so I dropped the pan and even checked/replaced the rod bearings (they were fine). I did find a couple of largish pieces which could have been from this broken piece.

The rest if the plastic pieces of the timing chain guide are all there.

04-19-2019, 10:56 AM	#1
cahme Second Lieutenant 114 Rep 226 Posts Drives: '11 E90 335i Sport MT Join Date: Jul 2015 Location: Texas iTrader: (0)	Timing chain guide slide rail broke at tip My car: '11 335i (although this part is same for all E90 non-M) Mileage: 168k mi My Valvetronic motor is no longer working, so I pulled the VC and found the tip of the "slide rail" broken off. I'm looking to get opinions as to what could have caused it? I did struggle a bit with getting the VC off, but don't see how that could have caught on the VC and I broke it then? My plan is to replace this top slide rail piece along with the chain tensioner and I do have the cam timing tool, so that won't be a big deal. I've attached a pic with the broken one (left) alongside of it from 2.5 years ago (right) not broken. Attached Images
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04-20-2019, 01:39 PM	#2
Gamb1t Major 598 Rep 1,343 Posts Drives: 330i,X1,Z4,Solstice GXP, RX-8 Join Date: Aug 2015 Location: Canukistan iTrader: (0)	Guess my question is what happened to that plastic shrapnel? And what long term damage it'll cause? Causes could be material fatigue overtime being beaten by a jump chain? How's the chain tensioner?
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04-21-2019, 07:11 AM	#3
Boland01 Lieutenant 149 Rep 460 Posts Drives: 2010 535ix, 2008, 2007 335i Join Date: Sep 2013 Location: Magnolia, TX iTrader: (0)	On our old E36 the plastic chain guides broke into small pieces. They then proceeded to clog up the oil pump screen. Noticed it when the oil pressure dropped. Worst case it can do some serious damage. That car had 125k back then when it happened.
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04-21-2019, 10:12 AM	#4
cahme Second Lieutenant 114 Rep 226 Posts Drives: '11 E90 335i Sport MT Join Date: Jul 2015 Location: Texas iTrader: (0)	I did have some small "bits" in my oil that were not silver from my last oil change. I could see them in bottom of oil drain pan, but not feel them rubbing between two fingers. My OPG was also leaking, so I dropped the pan and even checked/replaced the rod bearings (they were fine). I did find a couple of largish pieces which could have been from this broken piece. The rest if the plastic pieces of the timing chain guide are all there.
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