Timing chain tensioners

[Shotgun]

Hi all, I'm getting a tapping noise on startup and have been pointed in the direction of the main timing chain tensioners. Could anyone tell me if this advise is sounding about right and are the tensioners just a straight swap for a new replacement part? Cheers.

[X5Sport]

Version?

It's a swap after some fairly major surgery to get at them.  If yours is a V8 don't leave it as the repair for a broken/jumped chain is probably heading towards the value of the car!

[Shotgun]

Hi, sorry it's a 4.8 v8.

[X5Sport]

Do a quick search on here as there are a couple of very recent threads on this including one covering a broken chain following tensioner/guide failure.  The bill is well north of £5k.

[Shotgun]

Ok cheers.nice one.

[Greydog]

Morning
Don't panic just yet, you describe a tapping noise if it only occurs at cold start try letting all the lights cycle out before starting. I had a sticky Vanos solenoid this stopped it ticking at cold start. The Vanos solenoid was replaced no ticking.
The timing chain tensioner can be changed DIY quite easily have a look at www.meeknet.co.uk/scary noises, the tensioner is is a small spring assisted hydraulic ram. The spring provides pressure while the oil pressure builds (cold start) the springs can go soft if your lucky a change of tensioner will cure it about £40 plus some time. I did my own on the 4.4 I owned previously.
But as the old saying goes "Plan for war, Pray for peace" if you don't have one get a warranty. BMW V8's are good power producers but very fragile due to the internal plastics used after several heat cycles it doesn't take much for the timing chain guides to fail if they are allowed to slap around.
At Christmas my 4.6 suffered a sudden engine failure (no rattles or warnings prior to letting go) fortunately I do have a warranty. The engine was stripped for inspection and the consensus was either the oil pump failed killing the chain guides or the other way around.
As there was so much debris in the sump the warranty engineer sanctioned a complete engine clean and rebuild final bill £5250 + Vat which is just about what the car is worth without the warranty it would be a pile of scrap by now. 

[Shotgun]

Hi, I'll give the lights out aproach a try. Thanks for the advice. Cheers.