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1995 BMW 525i replaced head now won't start

Tiny
BIGKOF61
  • MEMBER
  • 1995 BMW 525I
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
1 month ago car overheated and shut down. Tore it down and found a cracked head. Put new head and new knock sensors on it. Now motor cranks but will not start. Fuel pump is good, coils are good. Just can't figure this out. Please help.
Thursday, May 14th, 2009 AT 4:38 PM

9 Replies

Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
I have forwarded your question to our BMW tech. He will be with you shortly, thank you for your patience
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Saturday, May 16th, 2009 AT 8:50 AM
Tiny
DOCHAGERTY
  • MECHANIC
  • 9,601 POSTS
When you replaced the head, I assume you got everything back the way it is supposed to be, so I wont waste time going back and rechecking your work. There is a possibility that there has been a sensor failure and/or some component of the wiring harness is pinched or shorted to ground, or there might be an outright failure of the DME. This will be difficult to pinpoint from here so you and I will need to get aligned on what has happened, so far what I have gotten from your story is that your lost power when overheated and you replaced the knock sensors, why? Were they melted? Have your ever done a cylinder head replacement on a M-50 motor before? It is possible the motor is cooked, did you run compression/leak down tests? What were the results? I await your reply.
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Saturday, May 16th, 2009 AT 3:38 PM
Tiny
BIGKOF61
  • MEMBER
  • 5 POSTS
I have done several heads before. This just seems weird that the car cranks real good. Have good compression. I just dont have fire or fuel. Checked the main relay and just bought new one as old failed all test. Also changed fuel relay. I am waiting on the crank sensor to come in to change it as the reading is about half of what it should be. As for the knock sensors, the were broken from the heat off the motor. This is a headache
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Monday, May 18th, 2009 AT 4:02 PM
Tiny
DOCHAGERTY
  • MECHANIC
  • 9,601 POSTS
Did the crank sensor solve the issue?
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Sunday, May 31st, 2009 AT 9:46 AM
Tiny
BIGKOF61
  • MEMBER
  • 5 POSTS
Still waiting for crank sensor
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Sunday, May 31st, 2009 AT 8:54 PM
Tiny
BIGKOF61
  • MEMBER
  • 5 POSTS
Ok replaced crank sensor today. Still won't start.
So far I have replaced knock sensors, main relay, fuel pump relay, crank sensor, head, plugs. Still no fire or fuel. Running out of ideas. Help!
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Monday, June 1st, 2009 AT 5:42 PM
Tiny
DOCHAGERTY
  • MECHANIC
  • 9,601 POSTS
Lets start with the basic stuff here. Do you have compression? Do you have spark? Is fuel being injected? Is there fuel pressure? Let us know what the findings are.
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Monday, June 8th, 2009 AT 10:35 PM
Tiny
BIGKOF61
  • MEMBER
  • 5 POSTS
I have compression about 115 psi
i do not have spark or fuel
i have a bentley manuel and have done all the test on this car that I can think of. Have a computer guy trying to run schematic on dme to see if it is bad.
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Tuesday, June 9th, 2009 AT 5:27 PM
Tiny
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If it is, I have a guy in San Diego that fixes them.
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Wednesday, June 10th, 2009 AT 5:51 AM

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