Defender's Black Smoke & Startup Issues, Help Needed

Hey there! I have some experience working on diesel engines, and your symptoms sound very familiar. I had a similar issue with my 2009 Discovery diesel last winter. Same problems, black smoke, engine light, and those nasty cold start problems. Took it to my regular workshop, and they found a damaged wiring harness connected to the fuel filter heater. The connector was corroded and causing all sorts of havoc. Got it fixed for about 110 Euro, and it's been running like a charm since then. Could definitely be the same issue on your Defender, but I'd need some more info to be sure. Can you tell me: Has the fuel filter been replaced recently? Are you getting any specific error codes? When did these symptoms first start? Just wanna make sure we're not overlooking anything else since Defender and Discovery models can have their quirks!

Thanks! Really helpful info about the wiring harness. My last service was about 3 months ago at 108704 KM, and that's when they changed the fuel filter. The symptoms started gradually over the last month. I'm getting error code P0380 (glow plug/heater circuit malfunction), which seems to line up with what you experienced. Think I'll get that wiring harness checked out first, seems like the most logical starting point given the similarities. The corrosion issue you mentioned makes a lot of sense, especially with these older Defenders. Fingers crossed it's just that and not something more serious! Would you mind sharing which specific tests your mechanic ran to diagnose the issue? Just want to be prepared when I take it in.

Hey again! Those details you shared definitely reinforce what I suspected. My Discovery had that exact same error code (P0380), and the symptoms started pretty much the same way, creeping up slowly until it got really annoying. The diagnostic process my mechanic used was pretty straightforward. First, they did a resistance test on the glow plug circuit, that's what confirmed the wiring harness issue. They also did a visual inspection of all the connections (that's when they spotted the corrosion) and checked the voltage at different points in the circuit. In my case, there was also a bit of water damage near the connector, which had caused the corrosion. These older Land Rovers can be pretty sensitive to moisture getting into the electrical connections. My mechanic actually showed me the corroded part, it was pretty nasty looking! Just one heads up though, when they fixed mine, they recommended applying some dielectric grease to the new connections to prevent future corrosion. Might be worth asking your mechanic about that too. Been about 8 months since my repair, and I haven't had a single issue since. Let me know how it goes with your Defender. Would be interesting to see if it's the same problem. These diesels can be tricky sometimes, but once you sort out these electrical gremlins, they're solid machines!

Thanks so much for all the detailed info! Really appreciate you walking me through your experience and the diagnostic process. It's super helpful to know about the resistance test and voltage checks, I'll definitely mention these to my mechanic. That's a great tip about the dielectric grease too. Makes total sense to protect against future moisture issues. I've booked it in for next week, and I'll make sure to ask them to check for water damage while they're at it. You've actually made me feel a lot better about this whole situation. Was worried it might be something major, but this sounds pretty manageable. I'll update you once it's been looked at, hopefully it'll be a similar straightforward fix like yours! Thanks again for taking the time to share your experience with the Discovery. These old diesels really do have their quirks, but you're right, they're worth the effort!