Nasty rattle from front of engine on cold start up.

Post Thu Sep 14, 2017 11:23 am

Hi, As all good problems this is intermittent but becoming more repetitive! First noticed after a week or so of non use. Started up and an almighty rattle coming from the front of the engine, cam chain/vanos cover, that could be felt and heard coupled with erratic idle that eased to normal idle/sound after a minute or so. Oil and filter changed about 1.5k ago; 5W 40 Shell Helix + OEM filter. Regular oil/filter changes every 6k max; never cheap oil/filter. After a longish run with no repeat I started it up 2 days later when it was fine until a stop after a couple of miles had the rattle and erratic idle back again resulting in a stall. Started up again and all was well! 2000 model, E46 323ci 145000 miles. Any thoughts would be welcome. Thanks.

Post Thu Sep 14, 2017 1:09 pm

my first thoughts are timing chain tensioner, i,m not familiar with this lump, but many car have a hydraulic tensioner which relies on the engine oil . i would get it inspected asap. or pull the covers off camchain cover.
and have a butchers

Post Mon Sep 18, 2017 3:07 pm

Thanks for your advice. Looking on the interweb; it could also be the Vanos bearings. But looking on the interweb usually makes me think I've got something incurable! Not always a good idea...

Post Mon Sep 18, 2017 4:10 pm

whats the vanos bearings ?

Post Tue Sep 19, 2017 9:31 pm

The camshafts move position according to engine requirements. BMW call it VANOS. The front bearings on the camshafts can wear in their casings apparently.

Post Tue Sep 19, 2017 10:03 pm

Vanos rattle its common repair kits are available on eBay

Post Sun Feb 18, 2018 10:26 pm

Most likely the vanos seals - they tend to go hard with heat and age being made of a variant of NBR rubber.
You'll want to get a upgrade kit to Vitron rubber seals, as this resolves the rattling issue.

The VANOS unit is bolted onto the front of the engine, needs the cooling fan removing to give enough clearance to get the unit off. Of note, you will need plenty of blue workshop cloth as there's an oil pressure line that needs to come off and can leak all over the place.

There's a number of guides online that will walk you through the process if you feel confident to do the job. or it's a half day for a mechanic to do the job.