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E34 (1989 - 1995)

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  #26  
Old 08-23-2013, 09:32 AM
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This appeared after the oil change, but I believe that's only coincidence....
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  #27  
Old 08-23-2013, 10:42 AM
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Quote:
Originally Posted by Doktor Bert View Post
This appeared after the oil change, but I believe that's only coincidence....
I have to agree. Do you think you could get a video up?
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  #28  
Old 08-23-2013, 11:23 AM
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Quote:
Originally Posted by Monsignor View Post
I have to agree. Do you think you could get a video up?
I'll try....funny that a chain/tensioner would be out on a 94,000 mile car. I have seen many M50's with 100-000 to 150,000 on the original chain...
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  #29  
Old 08-23-2013, 01:07 PM
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Quote:
Originally Posted by Doktor Bert View Post
I'll try....funny that a chain/tensioner would be out on a 94,000 mile car. I have seen many M50's with 100-000 to 150,000 on the original chain...
243k here on original chain.

Chain could just be worn from not being used.
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  #30  
Old 08-23-2013, 01:24 PM
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Tomorrow we will know...
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  #31  
Old 08-23-2013, 01:33 PM
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Originally Posted by Monsignor View Post
243k here on original chain.

Chain could just be worn from not being used.
I hate you.....
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  #32  
Old 08-23-2013, 01:59 PM
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I hate you.....
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  #33  
Old 08-23-2013, 02:01 PM
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Lol!
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  #34  
Old 08-26-2013, 09:20 AM
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After doing considerable research on this topic, I have discovered this is a fairly common problem. I found numerous threads where people simply walked out and got into their car after parking it several hours before and it cranked as if the plugs were removed - compression tests revealed 0 pis. Of all the threads I read, nobody has yet repaired the problem and in almost every case, they just replaced the engine or junked the car.

I spoke to a fellow in Newport Beach Saturday that has a 95 525i with 67,000 actual miles and he and his wife went to dinner, walked out 45 minutes later and the car cranked like the plugs were out. The local BMW firm recommended a replacement engine, so we will never know the exact cause, but I suspect a relaxed chain tensioner and/or bad VANOS.

I will pull the top off the M50TUB25 on Saturday....
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  #35  
Old 08-26-2013, 10:51 AM
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Quote:
Originally Posted by Doktor Bert View Post
After doing considerable research on this topic, I have discovered this is a fairly common problem. I found numerous threads where people simply walked out and got into their car after parking it several hours before and it cranked as if the plugs were removed - compression tests revealed 0 pis. Of all the threads I read, nobody has yet repaired the problem and in almost every case, they just replaced the engine or junked the car.

I spoke to a fellow in Newport Beach Saturday that has a 95 525i with 67,000 actual miles and he and his wife went to dinner, walked out 45 minutes later and the car cranked like the plugs were out. The local BMW firm recommended a replacement engine, so we will never know the exact cause, but I suspect a relaxed chain tensioner and/or bad VANOS.

I will pull the top off the M50TUB25 on Saturday....
in for motor teardown. I cannot see how a faulty vanos would cause this.
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  #36  
Old 08-26-2013, 11:11 AM
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Quote:
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in for motor teardown. I cannot see how a faulty vanos would cause this.

I actually suspect the VANOS more than anything.

During cranking, you can hear the engine spitting through the intake, as if the compression impulses are being vented out the intake valves, and since the VANOS controls the intake camshaft, if it was stuck in the advance position, this is a definite possibility.

Found many threads about this...
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  #37  
Old 08-26-2013, 11:29 AM
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I have a VANOS unit if you'd like.

So your theory is its trying to crank/fire out of time.
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  #38  
Old 08-26-2013, 11:31 AM
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Quote:
Originally Posted by Monsignor View Post
I have a VANOS unit if you'd like.

So your theory is its trying to crank/fire out of time.
At the moment, I suspect the VANOS, but I haven't had time to open it up just yet. Could you post a cutaway of a VANOS???

I need to educate myself on this system....
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  #39  
Old 08-26-2013, 11:46 AM
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Last edited by Monsignor; 08-30-2013 at 08:04 AM.
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  #40  
Old 08-26-2013, 11:57 AM
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Given that information, i can see where youre coming from in that the motor is trying to fire and turn over while it is not timed.

Yes VANOS will advance timing, but thats under circumstances. A worn tensioner would show the same effects just by being old.

Also please check out Part #16 in the above diagram. The crank is attached to the exhaust cam on the main timing chain, and the exhaust cam to the intake via another, separate, chain, with its own tensioner.
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  #41  
Old 08-26-2013, 12:05 PM
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Thanks!!!!
I will keep you posted and I greatly appreciate your input!!!!!
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  #42  
Old 08-27-2013, 10:02 AM
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VANOS - Very Awkward Non-functioning Ominous System

:-)
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  #43  
Old 08-27-2013, 10:45 AM
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LOL!!!

sounds like you feel as though you may have found the problem
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  #44  
Old 08-27-2013, 11:06 AM
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Quote:
Originally Posted by Monsignor View Post
LOL!!!

sounds like you feel as though you may have found the problem
Not yet, but I think it could be a combination of a failed tensioner and a stuck VANOS.
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  #45  
Old 08-27-2013, 12:03 PM
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Finding many symptoms of this in other BMW's:

Instant compression loss BMW M3:

http://www.m3forum.net/m3forum/showthread.php?t=246935

Sudden loss of compression:

http://www.bimmerwerkz.com/forum/3-s...ion-16512.html

BMW 325 sudden compression loss:

http://www.digest.net/bmw/archive/v10/msg01054.html

BMW 318 sudden compression loss:

http://forums.bimmerforums.com/forum...of-Compression

BMW 530i sudden compression loss overnight:

http://forum.roadfly.com/threads/187...ion-on-530i-v8
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  #46  
Old 08-27-2013, 12:24 PM
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thats alot of reading LOL. dont have time at work. will read through them when i get home.

I can't wait to see how vanos would cause instant total compression loss. Anytime i've heard or seen Vanos problems is the Vanos rattle.
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  #47  
Old 08-27-2013, 12:27 PM
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Quote:
Originally Posted by Monsignor View Post
thats alot of reading LOL. dont have time at work. will read through them when i get home.

I can't wait to see how vanos would cause instant total compression loss. Anytime i've heard or seen Vanos problems is the Vanos rattle.

me too. I am no BMW expert, so this will be a learning experience for me as well and I hope to get the E34 running so I can complete the restoration and, hopefully, my findings may shed some light on this apparently common problem.pe
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  #48  
Old 08-27-2013, 12:51 PM
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unplug the vanos solenoid and try to crank it.

This will disable the unit and potentially allow the motor to "retime." It WILL throw an engine light and if car does fire, it would only mean faulty vanos, not fixed car. It should be easy to follow under the intake manifold. Removing the airbox makes it much easier.
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  #49  
Old 08-27-2013, 01:04 PM
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Hmmmm....good idea, but isn't VANOS disabled until elevated RPM????

It is interesting that once you do get it started (after lots of cranking like it has no plugs) it does run and idles velvet-smooth with good power, so if valves were indeed bent, I don't think I would have a smooth idle when warmed up.
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Last edited by Doktor Bert; 08-27-2013 at 01:06 PM.
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  #50  
Old 08-27-2013, 01:32 PM
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the solenoid may not be reacting to oil pressure via revs. It may just be stuck open? as in cranking with the timing advanced? once the car is in accessories and the oil pump is primed, the timing is advanced. Thats my theory.

Give it a shot. theres no harm in it, and you would get a quick and dirty answer, or at least a bit more information.

Your valves are not bent after sitting.
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Last edited by Monsignor; 08-27-2013 at 01:41 PM.
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