It’s amazing that inline-six Cummins engines hold up as well as they do, considering the type of abuse diesel enthusiasts put them through. Not only are they stretched to triple their stock power levels, they’re spun a lot faster, too. That extra engine speed can lead to problems. One of the most common issues is that extra water pressure in the cooling passages in the back of the block can pop out a freeze plug or push through a corroded and rusted one. With the transmission in place, the freeze plug is barely visible (arrow). If you’re really lucky, and it is loose, you might be able to pry it out. But ours was corroded, so our only hope was to drop the transmission. With the transmission in place, the freeze plug is barely visible (arrow). If you’re reall This exact thing happened to our ’89 Dodge D250 when we accidently forgot to shift and spun the engine up to its 3,800-rpm governed speed. We smelled coolant and quickly found out the rear freeze plug was to blame. Unfortunately, to get to it we had to drop the transmission, so we enlisted the help of the crew at The Diesel Shop, located in Mission Viejo, California. They’re experts at all sorts of large repairs, such as engine and transmission rebuilds, so they were perfect for the job. Follow along as we make sure that rear plug will never blow out again! James Moring from The Diesel Shop had the labor-intensive job of removing the transmission. This meant removing the crossmember and converter bolts, pulling the driveshaft, and disconnecting the shift linkage, transmission cooler lines, speedometer gear, dipstick, and the actual transmission from the engine. It’s quite a bit of work and would have been a lot harder without a lift, so if you’re in the middle of an engine or transmission rebuild, it might be easier to address the rear freeze plug sooner rather than later. James Moring from The Diesel Shop had the labor-intensive job of removing the transmission After a lot of pulling, poking, and prodding, our old rusty freeze plug was out. So our rear freeze plug couldn’t come out even if we wanted it to, we got this cool freeze plug block-off that bolts to the back of the block from Keating Machine. It has an O-ring seal and is drilled and tapped in the middle in case a pressure bypass is required. Best of all, it was only about $50. Since it never gets below freezing in this part of California, we opted to just install a brass plug and let our other freeze plugs do the job. So our rear freeze plug couldn’t come out even if we wanted it to, we got this cool freeze Here’s the block-off plug and plate installed on the engine. Even with the transmission out, it’s still a tight fit. Here’s the block-off plug and plate installed on the engine. Even with the transmission ou Matt Stranz, one of the head technicians at The Diesel Shop also pressure- and smoke-tested our coolant system before we hit the road. It’s this kind of attention to detail that we like to see in shops. Matt Stranz, one of the head technicians at The Diesel Shop also pressure- and smoke-teste After we were sure all the air was out of our coolant system, we filled the radiator to the brim with a 50/50 mix of water and antifreeze. If you’re doing this yourself, make a few short testdrives and keep refilling the radiator to make sure all the air is out of the coolant system. Often, just filling the radiator up will result in an overheating truck. After we were sure all the air was out of our coolant system, we filled the radiator to th SOURCES Keating Machine 865-559-6499 www.keatingmachine.com The Diesel Shop 949-297-8477 www.thedieselshop.com By Jason Sands Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!