https://mercedesforum.com/forum/ Only diesel topics should be posted here. en Sat, 16 May 2026 02:43:47 GMT vBulletin 60 https://mercedesforum.com/forum/images/kirsch/misc/rss.jpg https://mercedesforum.com/forum/ https://mercedesforum.com/forum/diesel-discussions-33/primer-pump-leak-69044/ Thu, 14 May 2026 18:45:43 GMT I'm trying to replace the primer pump on an 84 300sd. I've tried several different ones (I have 3 of them). I've tried 1 copper washer and 2 copper washers. I've fully tightened them. Each time there is a slow drip from where the primer screws into the holder on the side of the engine. I've replaced primer pumps before and never had a problem. What should I try? ]]> Diesel Discussions noswendel https://mercedesforum.com/forum/diesel-discussions-33/primer-pump-leak-69044/ https://mercedesforum.com/forum/diesel-discussions-33/erratic-tachometer-behavior-69021/ Wed, 06 May 2026 19:42:10 GMT All of a sudden driving at about 55 miles an hour my tachometer began to wobble between 20 and 60 this went on for 15 minutes and when I slowed down in town traffic, I was pleased to see that it... All of a sudden driving at about 55 miles an hour my tachometer began to wobble between 20 and 60 this went on for 15 minutes and when I slowed down in town traffic, I was pleased to see that it returned to normal what causes this it just flopped back-and-forth ]]> Diesel Discussions Zeked https://mercedesforum.com/forum/diesel-discussions-33/erratic-tachometer-behavior-69021/ https://mercedesforum.com/forum/diesel-discussions-33/draining-fuel-tank-69017/ Mon, 04 May 2026 23:30:23 GMT I'll narrow my question. What's the best way to drain the fuel tank on a 126? ]]> Diesel Discussions noswendel https://mercedesforum.com/forum/diesel-discussions-33/draining-fuel-tank-69017/ https://mercedesforum.com/forum/diesel-discussions-33/car-out-long-term-storage-questions-69015/ Mon, 04 May 2026 01:47:19 GMT I'm setting aside my 81 240d for the time being. But, I have an 84 300sd that has been parked for about 9 years. It was running great when parked. I know some of the things I need to do, Any suggestions for what to do before I fire it up? What's the best way to drain the fuel tank etc.? Thanks. ]]> Diesel Discussions noswendel https://mercedesforum.com/forum/diesel-discussions-33/car-out-long-term-storage-questions-69015/ https://mercedesforum.com/forum/diesel-discussions-33/84-300sd-wiring-diagram-repair-manual-68988/ Sun, 26 Apr 2026 19:12:48 GMT I'm looking for a complete wiring diagram for a 84 300sd.I would also like to find a complete repair manual. I've found lots of providers online but when i check on them they are poorly rated for trustworthiness. Anyone suggest an honest source? Thanks ]]> Diesel Discussions noswendel https://mercedesforum.com/forum/diesel-discussions-33/84-300sd-wiring-diagram-repair-manual-68988/ https://mercedesforum.com/forum/diesel-discussions-33/84-300sd-repair-manual-wiring-diagram-68987/ Sun, 26 Apr 2026 19:06:17 GMT I'm looking for a trustworthy source for the above. At the moment I need the wiring diagram for the whole electrical system but I'd like to get a complete repair manual. When I check on the reliability for most of the online manual providers online, they are poorly rated. Anyone got an honest source? Thanks. ]]> Diesel Discussions noswendel https://mercedesforum.com/forum/diesel-discussions-33/84-300sd-repair-manual-wiring-diagram-68987/