Since I did my swap, I've had one niggling issue the last 4 years, which I decided to finally sort this weekend.
When the engine is hot, and the car sits in the sun on a hot day for a short period of time it often won't start; eg. drive to the shop, grab something quickly, come back to the car - no start. It seems like a heat soaked starter - as seems common on M50 engines. The car won't turn over at all.
Over the years I've tried various fixes - replaced the starter with a new one, checked / replaced and added additional earths, replaced the negative lead on the battery, replaced the unloader relays, all to no avail. On the interwebs there was a theory that in hot weather the starter gear and ring gear both expand slightly and this is the problem, including someone who claimed they'd filed the teeth of the ring gear and it sorted it. I thought this sounded a bit improbable, so got out the trusty e30 electrical trouble shooting manual and decided I'd keep pouring over it and testing things with a multi-meter until I found the cultprit once and for all.
The main symptom that pointed to a problem was that the auxiliaries like the heater fan and thermo fan weren't cutting out when the car turned over like they should pointing to the unloader relays. Since the unloader relays were replaced and that didn't solve the problem, the only thing that made sense was that there was a problem in the wiring loom between the ignition switch and the unloader relays.
To cut a long story short - I bit the bullet and decided to replace the whole black / yellow wire from the C200 connector in the steering column to the starter motor. Mine was a bit dodgy as I'd converted from auto to manual, in the process having to bypass the starter relay, so there were a lot of connections in that wire that a manual car doesn't have.
Voila - problem solved.
Seems if the black / yellow wire is a bit dodgy, it can't pass enough current for the unloader circuit to work properly. Now the auxiliaries cut out when the car turns over as they should and it starts every time :)
Anyway - obligatory pics.
I couldn't be bothered dicking around under the dash, so ran the wire out with the battery lead and then inside the plastic cover I've got on the firewall.
My interior could do with a big clean at the moment - been a bit too busy!
Steering column apart:
Running new wire (the auto parts store had no black / yellow wire, so yellow had to do!):
All buttoned back up:
So glad to have it fixed. Has been the only niggling issue with the car, which has been bullet proof other wise.
When the engine is hot, and the car sits in the sun on a hot day for a short period of time it often won't start; eg. drive to the shop, grab something quickly, come back to the car - no start. It seems like a heat soaked starter - as seems common on M50 engines. The car won't turn over at all.
Over the years I've tried various fixes - replaced the starter with a new one, checked / replaced and added additional earths, replaced the negative lead on the battery, replaced the unloader relays, all to no avail. On the interwebs there was a theory that in hot weather the starter gear and ring gear both expand slightly and this is the problem, including someone who claimed they'd filed the teeth of the ring gear and it sorted it. I thought this sounded a bit improbable, so got out the trusty e30 electrical trouble shooting manual and decided I'd keep pouring over it and testing things with a multi-meter until I found the cultprit once and for all.
The main symptom that pointed to a problem was that the auxiliaries like the heater fan and thermo fan weren't cutting out when the car turned over like they should pointing to the unloader relays. Since the unloader relays were replaced and that didn't solve the problem, the only thing that made sense was that there was a problem in the wiring loom between the ignition switch and the unloader relays.
To cut a long story short - I bit the bullet and decided to replace the whole black / yellow wire from the C200 connector in the steering column to the starter motor. Mine was a bit dodgy as I'd converted from auto to manual, in the process having to bypass the starter relay, so there were a lot of connections in that wire that a manual car doesn't have.
Voila - problem solved.
Seems if the black / yellow wire is a bit dodgy, it can't pass enough current for the unloader circuit to work properly. Now the auxiliaries cut out when the car turns over as they should and it starts every time :)
Anyway - obligatory pics.
I couldn't be bothered dicking around under the dash, so ran the wire out with the battery lead and then inside the plastic cover I've got on the firewall.
My interior could do with a big clean at the moment - been a bit too busy!
Steering column apart:
Running new wire (the auto parts store had no black / yellow wire, so yellow had to do!):
All buttoned back up:
So glad to have it fixed. Has been the only niggling issue with the car, which has been bullet proof other wise.
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