timing chain slap?

so today i changed my thermostat, coolant, and sparkplugs. when i reved the engine a little (to get the t-stat to open, so i could bleed the coolant) i started hearing a faint slapping sound. i started to up the rev's a little and the sound got a lot louder. Eventually i narrowed it town to the timing chain/ timing chain cover. when i opened the throttle, (i had my had on the cover) i was able to feel the vibrations. - not to mention the cover was friggen hot.

does anybody have any suggestions on what to change/do to combat timing chain slap?


1995 525i e34 -m50 engine
20w50 oil - just switched from 10w40

the only thing i could find is to change the tensioner. which i believe i just did about 8k miles ago.
- edit- nvm on the above statment. i believe it was the AC tensioner that i changed.

Sure it's not the VANOS unit failing? Common on the M50...

actually, it might be the vanos unit failing(aww not right now). what are the symptoms?

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Originally Posted by liquidtiger720

actually, it might be the vanos unit failing(aww not right now). what are the symptoms?

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Knocking noise. ;)

90% of the time, the tensioner piston fails. Not very familiar with this, but that's the most common form of failure.

is it okay to drive with this for a month or two?

I had the same sound especially after the engine warmed up. Got the spring, tensioner body and washer from BMA. Much quieter and an easy job. I noticed the old spring was about 1/8 " shorter than the new one. Oil the new piston before you screw it in.

how much was it gooch?

maybe just infamous VANOS noise but if you suspect more, perform what Gooch suggested. Before you replace that stuff, though remove it and inspect it...you can check the piston for wear as well...sometimes the pistons lose their prime and I am not convinced they need to be replaced....O ring may be leaky...prime the piston/pump up the tensioner with the access cap screw loose letting some oil wick out to bleed all the air out per Bentley.
In summary, getting titty slapped is much more enjoyable...something I enjoy every five minutes.
George

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Originally Posted by liquidtiger720

how much was it gooch?

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There were some earlier posts regarding a VANOS upgrade for 525s shipped prior than 3/95. It consists of about 4 parts I'm trying to source from BMA. I went to the stealer and they wanted $65 for bolts and shims. The fix is supposed to smooth the tourque on the low end and maybe reduce VANOS noise if any.