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).
The Problem:
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.
Data Points:
• 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,
Steve
(BigCat because I help care for a few. Check out the links below if interested.)
www.saveoursiberians.org
*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.