e38 - Engine tick / tappet problem??

Hi I have a 2000 740.
I have owned 2 previous 740s, and a 745Li.
None of my previous cars have had this behaviour that my latest 740 has developed.
At idle the car seems to 'tap / tick'. This is noticable up until about 2,500 rpm, where the noise gets drowned out. I had the car at my local dealership last week, and they said that they couldn't hear anything wrong. However, I am now convinced that the 'tick' shouldn't be there. A friend of mine is a mechanic for SAAB, and thinks it may be one of the hydraulic tappets... (?)
I can particularly hear the noise when the climate unit is off (ie. no other fans blocking the noise), and sat in the drivers seat with the window down. I've listened with my head under the bonnet, and it definately seems like there is a tap from the left hand bank of 4 cylinders (although it may be something else). However, the noise is definately from the left hand side of the car when facing it (ie. the right hand side, when sat in it).
Something which may (or may not) be linked, is that there is an 'oil spot' on one of the cylinder head bolts, on the left hand bank (ie. the noisy side)
Has anyone else had this problem?? Can you suggest what it is?? My BMW warranty expires on Sunday!!! but the car is booked back in to the dealership tomorrow, so I am going to insist they look again (as they said that nothing was wrong when the car was there last week).
Any help / advice appreciated.
Thanks
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Paul Aspinall wrote:

Yeah, a ticking at idle that goes away at higher rpm usually signifies a bad hydraulic lifter. Get the noise documented while under warranty so that you can get it addressed if it gets worse later.
What sort of oil are you using in this engine? Have you been religious with the changes?
-Fred W
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Thanks for the reply to this one.
I'm going to push the dealer to fix it. I'll also report it to BMW warranty also.
How much do you think this would normally cost to fix, if I had to pay for it??
Thanks

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Paul Aspinall wrote:

No idea, sorry. I do all of my own wrnech turning so I have nary a clue what they'd charge you, but the labor charges would be sizeable.
-Fred W
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Hi Paul.
I've just recently placed my car in to fix this problem.
I own a 1993 BMW 318i E36.
I had to replace:
Camshaft
Rockers
Tappets
The job cost me $1800 including labour!
I, as the owner, was most likely the cause i.e. infrequent oil changes. My mechanic (who I do trust, and has done very good maintenance on this car) advises that on BMW cars, every 6 months, or 10000 kilometers, whichever somes first, is the interval for oil changes. Also, the spraybar must be cleaned at every oil change. In the BMW, there is a tendency for the holes in the spraybar to clog up; thus causing the expensive problem that I had.
I envy you if you can get this repair on warranty.
I had exactly the same symptoms as you.
I used to leave the air-conditioner on high and the windows up to drown out the noise. Of course, it started to anny me when drivers passing by would start laughing at me and the car ;-(
Kind Regards,
-- Jason Tepoorten @HOME +61 433 176 821 (mobile telephone) snipped-for-privacy@tepoorten.com 8MP Australia

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Not to toss goo into the ointment here, but a serpentine belt can make a clicking noise that sounds just like a tappet. The problem may not be anywhere near as serious as you are thinking.
I can't imagine your car having sticky lifters at this early age. If it does in fact have lifter problems, the odds are very good that a chemcial treatment will fix it. When I was a kid, it was common practice to used a pint or so of automatic transmission fluid in the crankcase to free sticky lifters. The problem in those days is largely gone from the picture, but tarnish from the oil would clog the passages inside the lifter, and prevent the moving parts from moving freely. The ATF is highly detergent, and would clean the tarnish, allowing the lifters to operate freely again.
Today, they use stuff like Marvel Mystery Oil to accomplish the same goal.
Usually the sticky lifter will free itself as the motor warms up. If yours continue ticking, then I'd be looking at the belts before the lifters. There is Belt Dressing that can be applied, but the belts should probably be replaced.

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J Strickland wrote:

He could just run the engine for a *short* time with the serpentine belt off to see if the ticking is gone.
I assume (ass-u-me) that he (or anyone for that matter) could tell the difference between a ticking sound coming from outside the engine and one from inside. They do sound quite different...
-Fred W
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Thanks again.
The car has gone in again today. This time, I had the head service tech come with me and listen to the engine. He could hear it this week.... despite the other guy claiming he couldn't hear it last week.
He said they should be able to take care of it, under BMW extended warranty...... lets hope so!!!

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I would have thunk that too, but when I asked my mechanic to take a look at the noisy valves, he put some belt dressing on. It sounded just like a valve lifter to me, and I have a pretty good ear for this sort of stuff. Surely if one had a lesser ear than I, they would have thought the valves were making noise.
I agree thought that this is probably not the case, and the valves really are noisy. But, before dumping the check book into the valve train, it might be worth a shot of belt dressing. Just a thought.
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