Fried Something! Help!

[Curt2000]

I pulled the valve cover and intake manifold to clean and paint them to dress up the engine bay, turned out looking great but I screwed something up and now the car turns over but wont start.

I triple checked all the vacuum lines to make sure they all went back on correctly so I don’t believe a vacuum leak is the issue.

What I do think caused the issue is when I grounded my socket wrench on the battery terminal accidentally while I was torquing the valve cover down (picture below using fingers to point out arc point), I heard the electric arc snapping sound and some sparks flew.

I checked all the smaller fuses, didn't see any burnt ones. Not sure how to check the larger square ones.

Wondering if there are any quick guides to what items in the car are susceptible to ignition-off arc/grounding that I can troubleshoot, or any troubleshooting advice in general for this issue.

Thanks in advance for anyones help!


Before and after of my pretty but now non-functional engine

[e30austin]

sounds like you popped the fuseable link, which provides power to the main DME power wire, at the top most 10mm battery connection at the battery distribution block. to confirm this, you can give that wire 12v and see if it starts.

[bmwman91]

Yeah, sounds like the wrench handle bonked the 12V terminal block up on the firewall. That is the only place that should have oht 12V with the car off (if there was hot 12V elsewhere, there is also a fault causing it).

The fusible link is like 18" from the battery in the trunk. It is on the smaller black wire that follows the really large one. The big one is responsible for the starter & various 12V needs on the chassis. The smaller wire is dedicated to the ECU. The link is under some tape. It is crimped on to the wire, and it is a 50A unit. You can still buy new ones.
https://www.pelicanparts.com/More_In...-1-706-111-BOE

You do need to chop the old one out and crimp the new one in. Do not use shitty crimpers...get some high-force ratcheting ones. I personally own these and they are a great value. Worst case, if you do not plan to work with uninsulated crimps after this, you can sell it and get most of your money back.
https://www.parts-express.com/Pro-Cr...-2-AWG-360-646

Because you will be chopping the old link out, the wire will end up ~1" shorter and you may need to untape a few more feet of it in order to pull in some slack from further up. When I replaced mine, I chopped one out of an E30 at a wrecking yard, so I had some extra wire to work with and used 2 yellow butt splices. Now that I think of it, make sure that you can actually get that 1" of extra slack before you buy the OEM replacement lol...

When done, rewrap the link and wire with some quality electrical tape.

[Curt2000]

sounds like you popped the fuseable link, which provides power to the main DME power wire, at the top most 10mm battery connection at the battery distribution block. to confirm this, you can give that wire 12v and see if it starts.

Thank you!!

I have a mobile BMW mechanic guy coming tomorrow and I’ll see if he can bring that part specifically.

[Curt2000]

Yeah, sounds like the wrench handle bonked the 12V terminal block up on the firewall. That is the only place that should have oht 12V with the car off (if there was hot 12V elsewhere, there is also a fault causing it).

The fusible link is like 18" from the battery in the trunk. It is on the smaller black wire that follows the really large one. The big one is responsible for the starter & various 12V needs on the chassis. The smaller wire is dedicated to the ECU. The link is under some tape. It is crimped on to the wire, and it is a 50A unit. You can still buy new ones.
https://www.pelicanparts.com/More_In...-1-706-111-BOE

You do need to chop the old one out and crimp the new one in. Do not use shitty crimpers...get some high-force ratcheting ones. I personally own these and they are a great value. Worst case, if you do not plan to work with uninsulated crimps after this, you can sell it and get most of your money back.
https://www.parts-express.com/Pro-Cr...-2-AWG-360-646

Because you will be chopping the old link out, the wire will end up ~1" shorter and you may need to untape a few more feet of it in order to pull in some slack from further up. When I replaced mine, I chopped one out of an E30 at a wrecking yard, so I had some extra wire to work with and used 2 yellow butt splices. Now that I think of it, make sure that you can actually get that 1" of extra slack before you buy the OEM replacement lol...

When done, rewrap the link and wire with some quality electrical tape.

Wow, you guys are pros! Wish you were in San Diego, but this level of detail is next best thing, THANK YOU!

[bmwman91]

Cool, let us know how it goes. I am curious to know how the mobile mechanic approaches it.

[Panici]

As said, likely your fusible link.
Had a parts car some years ago that wouldn't start due to a corroded fusible link. Replaced with a piece of wire for testing and it started right up.

You may want to use an aftermarket fuse in place of the fusible link for cost/availability reasons.
Just make sure whatever you use has the right gauge (thickness) of wire and a properly sized fuse.

I recommend solder and marine-grade heatshrink, but others swear by crimp connectors for automotive applications.

Something like this:
https://www.amazon.com/AUTUT-Automot...ve&sr=1-3&th=1

[Curt2000]

As said, likely your fusible link.
Had a parts car some years ago that wouldn't start due to a corroded fusible link. Replaced with a piece of wire for testing and it started right up.

You may want to use an aftermarket fuse in place of the fusible link for cost/availability reasons.
Just make sure whatever you use has the right gauge (thickness) of wire and a properly sized fuse.

I recommend solder and marine-grade heatshrink, but others swear by crimp connectors for automotive applications.

Something like this:
https://www.amazon.com/AUTUT-Automot...ve&sr=1-3&th=1

Perfect thanks! 🙏🙏🙏 I’ll run to autozone now to see if they have them.

[bmwman91]

Nice, yeah one of those would be good too...easy servicing if something ever happens again. The stock wire is 6mm^2, which is approximately 10ga.

Crimps are generally considered ideal connections in automotive applications...provided they are done properly.

[Curt2000]

Cool, let us know how it goes. I am curious to know how the mobile mechanic approaches it.

He got overwhelmed and cancelled, i sent the car to La Jolla Independent BMW this morning because Im confident I can do mechanical but not electric