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  1. #1
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    Tight or Sticky Valves?

    My M5 has a miss and I am trying to figure it out. One of the cylinders is not firing at idle but as the rpms increase it smooths out. However, at idle it sounds like a 350 ss Camaro. My valves have not be adjusted since the head was reconditioned at 120ish. I now have 157k on the car.

    Given this about a year or two ago I ran over a pre hung door in the middle of the pa turnpike and destroyed my exhaust system. I had to replace a header pipe and about two weeks later my cat disloged in side turned side ways and my car would not rev over 4500 rpm. I drove her easy home took off the pipe and gutted the cat.

    Is it more likely that a good valve adjustment will solve the problem or do I have bent valves? I guess the only real way to find out is to take her apart. The down side is I have enough to perform the adjustment but not the valve job.

    The car drives great and still gets good mpg. However, she is running very rich smelling because the fuel in that cylinder is not burning off all the way.

    I did a compressioin test (25 psi in that cylinder) but not a leak down test. has anyone ever had sticky valve/s?


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    Re: Tight or Sticky Valves?

    More then likely a burnt valve. A leak down will confirm it for sure. You will probably hear air passing through the exhaust valve. If you have the header ports take the cap off and you'll hear it.

    Definately do the valve adjustment and I'll bet you find that the cylinder in question has tight exhaust valve clearence. You can try to set the proper clearance, then test the compression for that cylinder again..., but if you don't have an improvement the head must come off.

    Sounds like a valve job is in need. Take a look at my previous post with pics of my split/burnt valves. If you can't find the link let me know.

    Philo.
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    Re: Tight or Sticky Valves?

    Thanks Philo. I am really upset and perplexed by this. I have really taken good care of the car since purchasing it 5 years ago. I was saving to get the body work done and this happened and my insurance will not cover it. I miss driving her soo much nothing sounds and drives quite like a well tuned s38 in my eyes. If it is the valves that need the work I might just take her off the road all together and just start saving, becuase no one will want to buy a e28 m5 with a down cylinder. My 325es is fun to drive but has no balls compared to the m5. I really want to get to the track this year, but again it looks like a no go. Third year in a row. I do not know what is worse, not having the M5 or having it broken and off the road to look at everytime I exit my house.
    Maybe I will sell them all and buy a Prius and a pocket protector.

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    Sorry to hear

    Let me know if I can help

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