I have a real trooper of a '95 M3 with 276k/mi. on the original block (reman. head, 3rd used ZF trans. just went in two weeks ago, and updated suspension, but otherwise stock).
Basically, the car doesn’t want to crank sometimes when it’s warmed up. A few years ago a problem started (or didn’t start) where the car would intermittently fail to turn over if the engine was brought up to temp and I parked somewhere for 15-30min. then came back to start up and drive off. Being a manual, I took to parking on inclines so I could bump start it when this happened. Living in Kansas, those inclines are not always easy to find.
• When attempting to crank, the display dims a little as if current is being drawn
• There is sometimes a click like the solenoid is engaging, but after a few attempts it will stop clicking, or it won’t click at all from the outset
• Even without the clicking, the display still dims as with current draw.
• The problem is inconsistent, sometimes there, other times fortunately not, and happens summer or winter
• It has occasionally happened when the engine was cold (first start of the day), but almost always starts cold (99%) or after the car has sat for an hour or more
What I’ve Done:
• Replaced starter (twice) with new units (crank was never weak, it was always all or nothing)
• New battery (with no difference in cranking ‘authority’), old one worked as well as the new
• Replaced engine ground strap and added another ground connection directly to starter body (starter bolts to Al trans. housing so ground jumps back to block then ground strap)
• Cleaned all positive lead connections in the engine compartment from the jump terminal (battery is in the trunk) to the fuse block and starter/solenoid
• Replaced battery ground strap in trunk
• Soldered a bridge to bypass the EWS II anti-theft module*
So, my mind won’t leave the premise that there is a weak contact somewhere that is irritated by elevated temperatures and weakens, then contracts when it cools and restores enough connectivity to crank the starter, leading to the symptoms I’m seeing. I have NOT examined any connections past the battery positive terminal to the jump terminal in the engine compartment, but I understand there is a fuseable link inline.
I’m hopeful that the symptoms (dimming display) resonate with someone who has had similar problems and can point me in the right direction of how to diagnose/troubleshoot this or what to look for.
Thanks in advance for all shared wisdom or witty non-sequiters,
(BigCat because I help care for a few. Check out the links below if interested.)
*EWS II is an anti-theft system that uses an antenna ring around the ignition cylinder to talk to the RFID chip in the key and will interrupt either starter or spark. I bought the car in 2001 with 96k/mi. on the odo. The PO apparently had issues with the unit as it has a sticker post '95, and the ‘fix’ of jumping the starter wires was already done when I examined it, but with the aluminium press-fit connectors you can buy at a hardware store, so I removed it and soldered a proper jumper in its place.