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Discussion Starter · #1 ·
hi there i have a 1999 735il e38 m62 3.5L and i have replaced the timing chain guides,after getting the car running it seemed to have a roughish idle and lacked power on acceleration.I set up the vanos units correctly with a multimetre also had the cams and cranked locked in to position,but thats not my real problem at the moment my prob is after moving the vehicle i turned the engine off and went to restart it moments later and now it wont start,the engine sounds like it has no compression has anyone come across an issue like this?
 

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First thing I would do is get a tool on the crank pulley bolt, and turn the motor by hand, checking to see if the pistons have hit the valves. Hopefully this is not the case. Or you could do a compression test to make sure it has not lost compression.

It may also be something small like a loose electrical connection. I'd go over everything on the top of the motor first to make sure everything is in the right place. You should also try scanning the computer to see if there is a code stored.
 

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Discussion Starter · #4 ·
hi i have done a compression test an every cylinder is down.Cylinder 1 is at 30psi and the rest are at 75psi i would have thought that if the valves had hit the pistons it would've made a noise.Is it possible that the bore has failed ive read online that they had some issues.
 

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I am just curious ...how you did the compression test? The readings are too low...30 PSI and the rest is at 75? That doesn't sound good.
I am not familiar with the 3.5 L engine but you should make sure first that your timings marks are were they supposed to be. If they are not , the valves might be slight open when the cylinder is coming up for compression and this could be a reason for your low readings. If the timing marks are right , do the compression test again and turn the engine about 12 times to make sure that you have a good reading. I turn the engine about 15 times /cylinder. Then post the readings again for all cylinders.
The rough running engine that you said you had could be from misaligned vanos. But engine should start anyway.
A good friend of mine who is a mechanic , was sitting next to a car at his shop when a timing belt broke when the car was idling. It was a 4 cylinder engine and 2 valves were hit on cylinders 1 and 4 . The sound made by the impact it was not big, almost not noticeable. Somebody thought that a tool was dropped on the floor. So I am trying to say that , if that really happen , you might not even notice the noise. If that really happen you should have low readings in at least 2 cylinders because the cylinders runs in pairs.
The issues, what I think you read , (with the failed bore) are related to the nikasil blocks running on US gas(low octane #) . The issues are in US only. You should not have this problem and this is something that becomes progressively worse. Not suddenly.
First lets clear out something :
Is the engine with the timing marks right?
Have you turned the engine as stated by balance by the hand?
If yes , have you felt something hitting in there?
What are the ,, good" readings for all cylinders?
 

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Discussion Starter · #6 ·
yes i have checked the timing it all seems to in line i locked the crankshaft and cams with the special tools.when i turn the engine the bank 1 vanos unit seems to stick for a moment like the camshaft is turning in the unit but when on tdc the cams line up with the crank,the initial problem was the timing chain guides had broke an i wonder if that has anything to do with this issue?
 

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It's good that the timing marks are straight. Initially I thought that you have installed the chain too loose and make the chain jump. Vanos units are DME controlled and if you have issues with them you should have a stored code. I don't think that Vanos units could be blamed for a non start situation.
What about the compression test?
 

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Did u bar the motor over by hand b4 running it ?
 
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