When do I replace the timing chain on my Wreg SLK 200 it as only done 23000 miles from new. I do not know if it requires changing on age or the milage

I don't know of any motor that requires the head to be removed to change a timing chain or belt.

It depends on the vehicle, and the climate.
But a timing belt is expected to last for 60,000 miles and a timing chain should last the life of the engine, say 175,000 miles.
Some timing belt engines are interference engines, which means the valves can be damaged if the belt breaks while the engine is running. I recommend replacing the timing belt before 80,000 miles unless the vehicle runs in a hot climate.

I must presume you have verified that you do indeed have a timing belt and not a timing chain. (I'm reasonably certain you have a belt, I think the 2.4L engine uses a chain.) Your owner's manual should specify the replacement interval, typically 60,000 or more commonly 80,000 miles. If you're coming up on the 80,000 mile mark, change it. If you bought it used and it's over 80,000 and you don't know if it's been changed, then change it. If that's an interference motor, it will destroy itself if the belt breaks. When having the timing belt changed (or doing it yourself), it's a good time to change the water pump (even it it's fine....simply because you have access while changing the belt), all hoses and other belts. It just makes sense to do these other things while you are doing (or having done) the considerable disassembly / interference removal required for the timing belt work. Shop around and get the required parts, take everything to a mechanic you trust or take a couple days off work and do it. I don't know you or your level of expertise, so my apologies if I'm preaching to the choir.

Why do you need to? Who told you it was bad? Just because you car won't start, doesn't mean it has anything to do with the BMW chain.The timing chains are double roller chains that are probably the last thing that would ever break no matter how many miles are on it (200, 300 or more thousand). They are also incredibly complex to change (BMWs have variable hydraulic timing) and require specialized tools not available except by special order. It requires a lengthy engine dissasembly. If you have changed timing belts and chains on other cars and feel you might as well try BMW, then my advice is to sell the car now, because it will never run again.

You should replace the timing chain every 60-80,000, but if you are like me, I have 300,000 and never changed it. It is all about preventive maintenance. If I had a double overhead cam or something I would have changed it.I have seen timing chains go at 20,000. That's a choice that only you can make. Timing chains break without warning, so a new one is always nice , but personally, I think they just scare you into buying a chain every so many miles, so that you buy another one.Money grab. Good luck

If its never been done, just due to age it would be good to due it and guides before any issues developp.

It has a timing belt. Recommended to be replace every 105,000 miles, timing belt also run's your water pump good idea to also replace, your engine is also an INTERFERENCE ENGINE which will damage your cylinder head valve's if timing belt goes bad. Hope this was very helpful.

Does not require this service, as the motor has no timing belt, it is a maintenance free timing chain.

No.....you do not have to change the timing chain due to being parked....it is wise though to follow manufactuers specs on WHEN to change it.

There is nothing wrong with your timing chain.

Is it you maintenance light(service eng ) or is it your require oil chance light? If it is your change oil now light look in our manual it should tell you how to reset it. Let me know which light it is.

Cheers