Any BMW sleuths that can figure this out

Thanks to Stone-IslandV8 & Bigian for your replies.

I wonder if anyone can tell me if you need to dismantle any engine components to replace the lambda sensors. Camshaft position sensor looks straightforward and you can see it at the front of the engine.

Just wondered if the garage has forgotten to replace or tighten something up.

Also wondered if anyone else has suffered such a catastrophic failure after replacing sensors.

Thanks for all your reponses.

RAC transported the car back to the BMW specialist on Monday morning. I felt that I had to give the guy the chance to reflect back on his work. My main problem here is that the car has been reliable (albeit sluggish) but that the engine failure occured just fifty miles after it had been in his garage.

All I can deal with is facts and not guesswork.

The engine judder that was apparent under braking was NOT there when I took the vehicle in, only when I picked it up. I called him at the time  to tell him about this. He told me that he had replaced two tie rods (which he had ) and that this was causing the judder and would eventually go away. The judder was not from the brakes it was from the engine. There was also a slight tapping noise but I discovered one of his screwdrivers under the bonnet which was causing this noise.

The guy called me this morning to tell me that he needed to "dismantle" the engine for further investigation. He said that the timing chain may have slipped as a possible cause. That the hydraulic bit for this could have failed. Or it could be something completely different. (nothing like covering all your options!!!!!!).

He said that he does not know what causes the engine to make an extremely loud screech at 8-10mph and for the car to pull up as if the brakes had been applied hard, but that this could be the transmission?

He further said that it was going to be a big job and that I would be without the car for weeks.

If you read the first bit of my post you will see what the original local jobbing mechanic told me. "that the timing chain had slipped and that it would cost thousands to fix". This is the reason that I took it to a BMW specialist. The BMW specialist told me that he had never come accross a failed BMW engine and that if I spent the £700 on sensors the car would be fine.

Now it would appear that the original mechanic (local guy who does bits and bobs) could have been correct. If this is the case I have spent £700 for nothing (on the advice of a specialist). And, still have to fork out for a new engine, and may have ended up with a knackered transmission for good measure.

This would end up costing more than the car is worth!!!!!!

Does anyone want to buy a knackered BMW 523i SE?

my faith in BMW specialists is starting to erode.

Does anyone out there have any suggestions how to get myself out of this mess. (no high cliffs or buildings where I live so jumping off is not an option)

I agree with Stone Island.

There is little to be gained from throwing lots of money at a car with 145k on the clock.  

I don't want to be unfair so I won't name him but he adveritises on the web as being a BMW specialist with over 10 years experience.

Logic also tells me that a catastrophic engine failure can happen at ANY time. What I can't get my head around is how soon after he had done work on the engine that it failed. Have I just been very unlucky?

The engine judder under braking I think is significant. It was apparent at once after I picked up the car and I told him so. It was NOT there when I took the vehicle in.

His comments that the cylinder head gasket had been replaced VERY recently is also puzzling. The head as never been off as long as I have had the car for sure. The other mechanic only had the car for two or three hours and he swears blind he never touched it.

Obviously the BMW specialist is now covering his corner and will eventually tell me that whatever has happened was unfortunate and was not down to him, although how he will "front" this to me will be worthy of an oscar for sure.

Can anyone tell me precisely what would happen if the timing chain were to jump a tooth or so. Would the pistons and valves collide and what would be the resulting damage? The engine was still running when the RAC man started it but it was missing on a couple of cylinders and the timing chain was slightly noisy. The car even drove forward out of the drive at about 5mph but any attempt to go over this speed and the horrible noise and engine braking occurs.

Thanks for all your help/comments so far

Sorry to hear about your troubles but just to add my 2 pennorth. In my experience, a timing chain would only jump if either the chain tensioner had failed or if the chain had stretched badly, the latter of the two would happen over a very long period of time and would be noticable long before failure. If it has slipped, the head would have to come off to see if there is any damage to the valves or pistons (if they have come together)

What grounds has this BMW specialist got to think the head has been off recently, I'm sure the only way to tell is to take the head off and inspect the gasket so how can he tell?

Not discounting what you are saying but for an engine to judder under breaking is strange. The braked being applied has no effect on the actul running of the engine at all. The brakes use the vacuum (which is created by the engine) from the servo to assist the braking but this should not affect the actual engine running at all. The judder under braking can be caused by either warped brake discs, uneven pad wear or worn track arm bushes on the front suspension.

Has the car been regularly serviced and the oil checked. Has it ever run low on oil?

As mentioned before, it may be a good idea to speak to trading standards though they may advise you to take to a BMW dealer and get a full diagnostics done but then if the BMW specialist is found to be at fault, he would be liable for all costs incurred but you'd have to shell out more first.

Citizens advice may also be of use but I think trading standards is best, see here  http://www.tradingstandards.gov.uk/index.cfm

I hope you get it sorted soon. Unfortunatley there are a lot of bad garages out there and finding a good one is a lottery, usually word of mouth by happy customers is the best way.

Mike

Just picking up on a comment from Mike (540 V8)

if it is right to assume that the way to tell if a head gasket has been replaced is to take the head off again then I should be prudent.

In the back of my mind I think he has been messing with the car. Problem is that this is anecdotal thinking on my part with no substance.

Maybe the clean(er) engine oil is a pointer to this. Do you think it would help if I told the specialist to keep any parts/gaskets he takes off for me to have inspected. Could I then determine if the gasket was recently fitted? (if it has then he must have done it)

I don't think I am being unreasonable here. The car was running fine (albeit sluggish) before I took it in. It has also been very reliable.

Just heard from the BMW Specialist.

He reports that the situation is not as bad as thought.

He says that he thinks that the valve gear has jammed and that he will sort it out. No mention of any costs so far.

The Trading Standards Office think there is a clear cut case for him to rectify the problem at no cost to me.

So far I have not run this by him. I think that I should allow the opportunity for people to behave reasonably. My wife disagrees with this. She thinks I should go round and launch him around his garage. The logic of women always amazes me!!!!!!!!!!!!!!

To date, my faith in human nature remains intact. But stay tuned!!!

Thanks for your comments UweM3

Just been up to the garage to collect another shed (little peugot hire car) from him.

He seems to have BMW's all over the place from customers so must do a good trade. There is something wrong about this situation but can't put my finger on it. I need to let this play out a little longer before going in to him about the fifty miles, trading standards etc etc.

He needs to talk to me quite quickly and I am suprised he has not so far. I am quite prepared to be reasonable about the whole episode eg, if he sorts the car out properly and professionally I will meet some of the costs. As it stands he is a bit of a BMW renegade and drives round in a very big/new/expensive Audi so I don't feel too sorry for him.

I will keep you posted.

PS: Very good forum here. I am a webmaster/site designer. If I can help with links etc can someone let me know