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Discussion Starter · #1 · (Edited)
hi there my bmw 840 cia sort 1998 s plate is making a tappety noise in the cam cover..i havent used it this year..but start it up now and then...last week it was fine....started it today and tappety on right side as you face engine....it did this about a year ago...was worse...then it disappeared, any suggestions, thanks jim:
 

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Could you please remember to add the vehicle details in the thread title next time as per forum rules please, they have been done for you this time. It makes it far easier for people looking up help for their own problems or conversions.

First of all, have you checked the oil level?

And how long did you run the car with it making this noise?
 

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Discussion Starter · #3 ·
oops 1998 bmw 840 tapping noise

hi ronnie...i started the car up for about 2 mins..then drove round the block,,about 5 mins...yes always check oil and coolant...never uses any of either, thanks jim....do you think it might need a long run...jim
 

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I agree with Ronnie - a common issue. You haven't stated the mileage of the car but in my experience with BMW engines tappets start to get noisy between 150-200k miles and engine efficiency tapers off above 200k due to late valve timing and piston blow-by. This statement is based on M30 and M70 engines.

It is easy to recognise tappet noise once you know how it sounds. You can locate the source of the noise using a long screwdriver, at least a foot long, by holding it against various parts of the engine and putting the handle to you ear. Be very careful if you have long hair and avoid wearing clothing that may get caught by moving parts if you do this. Also, keep a suitable distance to moving belts and pulleys - the engine will not stop if you get a finger trapped. Finally, a second person should be present. This test method is useful if you don't have a mechanical stethoscope but it is potentially dangerous because in order to put your ear to the screwdriver you need to turn your head away from it so you can't see it, and if the engine idles roughly it may push the screwdriver away from the point you are listening to. Sorry to sound like H&S but I've seen screwdrivers used in this way hitting rotating parts and being thrown out at very high speed.
 

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Discussion Starter · #6 ·
bmw 840 tappety noise

This site is FANTASTIC..I came across it as i typed in bmw mechanic on google but I never came across it before, thanks to the replies so far from ronnie and
Talyinka...i forgot to mention my car has done 256000 miles full main dealer service history and never missed a beat until now,,,,so maybe as its been laid up ..i hope its just a sticky valve ot dirt...if anyone else can help, i would be grateful, thanks again jim.;)
 

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http://www.meeknet.co.uk/E38/Tappets.htm - nice article. A good drive allowing the oil to reach operating temperature throughout will do the same job :).

Hydraulic tappets do wear out over time and lose the ability to counter the pressure of the valve springs, opening the valves in a timely fashion. 256k miles is a decent distance by any measure. I have found that the fuel economy of my 7-series cars have started to deteriorate seriously at around this mileage. I've never had an 8-series with that much on the clock.
 

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Discussion Starter · #9 ·
bmw 840 cia what tappet noise

thanks to ronnie and tally...i stared the car up last night..guess what...not a tappety noise to be heard....car drives great....fuel consumption about 20 mpg if used normally.....car has full main dealer service history...27 stamps in the service book,,was serviced 3 to 4 times every year.....i put 19 inch alloys allround with new tyres..spare x bolt is as new...interior is very good no rips or tears on seats..everything works, but hey got a fright,,,when i heard the noise..lol:hihi.i only used it as a 3rd car to get a buzz....still pulls strong...
i paid 43 grand for my old 840 cia non sport on a 1996 plate and it was 18 months old....this one cost me 5grand ..and a grand for wheels and tyres...one other thing,I have put a new battery in it..I've replaced it twice as it went flat..nothing left on..but only started it once in a week.....would the alarm do this? CHEERS jim
 

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I find that my 850s use up all the soup on their batteries if standing still for about 10-14 days, a pain in the airport car park - at home I normally plug them into a trickle charger. My 730 last longer, maybe three weeks or so.

If your car seems to use too much stand-by power stick an ammeter (or two :)) in series with the batteries and measure the consumption. I'm not sure how much it is supposed to be but that figure can undoubtedly be found.

Quoting fuel consumption, how about this: Some days ago I drove 600 miles in my 850 (A-roads, country lanes, town traffic, motorways) - average 22.7 MPG. Beat that :rofl.
 

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thanks to ronnie and tally...i stared the car up last night..guess what...not a tappety noise to be heard....car drives great....fuel consumption about 20 mpg if used normally.....car has full main dealer service history...27 stamps in the service book,,was serviced 3 to 4 times every year.....i put 19 inch alloys allround with new tyres..spare x bolt is as new...interior is very good no rips or tears on seats..everything works, but hey got a fright,,,when i heard the noise..lol:hihi.i only used it as a 3rd car to get a buzz....still pulls strong...
i paid 43 grand for my old 840 cia non sport on a 1996 plate and it was 18 months old....this one cost me 5grand ..and a grand for wheels and tyres...one other thing,I have put a new battery in it..I've replaced it twice as it went flat..nothing left on..but only started it once in a week.....would the alarm do this? CHEERS jim
Check for a parasitic drain Jim :thumbsup http://www.wikihow.com/Find-a-Parasitic-Battery-Drain
 

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Yeah, right method but the value of 20-30mA is surely obsolete - that's only around one third of a watt. With modern alarm systems and computer stand-by I would think around five to ten times that figure.

What are the batteries in an e31 - around 40Ah each? If they die in two weeks, that's 336 hours, this corresponds to a consumption of 80/336 = 0.24A = 240mA, i.e. at 12V, 2.3W. I think that sounds quite reasonable, perhaps a tad high but not out of range...?

In any event, a couple of ammeters in series with the bats is the starting point.
 
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