Hi all, hope this is not a stupid question. would the car continue to crank without starting if the timing chain had gone?.here's why....got up for work Friday morning and got in car at 6.15(parked in garage overnight)clicked to unlock and got in ignition came on and heard pump prime. car started on the button perfectly and ran fine, no missing.. plenty of power..no rattles.drove to work approx. 15 miles without no concerns. parked at work for app 20 mins for meeting and started fine again, drove to where im based all day app 1mile away and parked up, car was then left app 8 hrs without being started or moved, I unlocked and got in and the car just cranked without firing it wouldn't even attempt to fire and had no engine warning lights. I tried a few times then left it overnight and went back next day with the AA man, he first said timing chain but couldn't understand how it would go being parked and the fact I said it had been fine earlier. He then said maybe a stuck inlet valve or fuel pump but said as he could smell petrol fumes so it was unlikely to be that, but on locking and unlocking I could not hear it prime?. Car was then taken to where it was purchased as under warranty there and this evening was told they are taking off engine covers and things to investigate further but they suspect timing chain .I still fail to understand how can the car continuously crank without firing if the chain had gone? surely it would be making a terrible noise, valves rattling and the like? Also if it was the pump failure would I get engine management fault? Please help as im not looking forward to find out if it is chain and the cost.

I would have thought you would have heard a really bad sounding noise whist driving/starting if it was the timing chain? Could be some kind of immobiliser issue?

I would suspect it is electrical.

What I would of done is pulled a plug and tested for spark

Time chain failure; I've ran an engine with no timing chain on and the first thing you would notice is the engine spins really quickly (Less frictional force from the Cams). What does it sound like when you crank it?

I "Doubt" it's timing chain. Not impossible but unlikely considering your detailed description of the situation.

I don't think the engine is getting Spark. This is more probable. If the AA bloke smelt a strong smell of petrol, I imagine it's getting fuel. If there was a spark, you would hear Popping noises where the fuel is being pushed up onto the plug contacts by the pistons and have it blown out the open valves as it reaches TDC. Literally sounds like intermittent "Pops".

It's in the right hands now (where you got it from) so lets hope it's a nice and easy fix. "No spark" is better than timing failure¬! haha

Keep us posted

Daz

Hi guys, the problem turned out to be the timing chain slipped a tooth. the chains rarely snap on these according to bmw just stretch. this along with the fact that the tensioners and guides are made of nylon and wear down, and the lifters are hydraulic and move up or down when the car starts or stops to create tension, apparently when the car stopped they dropped as they should but when started again they did not lift and create enough tension causing the chain to slip a tooth. when I asked how this did not do any damage to valves etc. I was told that there is a difference between cars with belts and chains as if it was a belt then it would go BANG, but this set up on the beemer just cause the chain to spin without affecting the rest.....thank god. anyway £800 pound later :( and new timing chain, lifters, tensioners and guides and labour ..its now running sweet as a nut, seems to be quieter, smoother, better throttle response and more responsive :D. right for a few years now lol.

unlucky but then again lucky lol

your one of the rare uncommon causes, glad its sorted for you - -

unlucky but then again lucky lol

your one of the rare uncommon causes, glad its sorted for you - -

Yeah, pretty unusual. Yes the tensioners are of plastic/nylon construction but are very good at what they do.

the tensioner piston is indeed hydraulically operated and works on oil pressure. Did you have enough oil in her?

Yep Deffo Tensioner replacement...