A Guide to Diesel Transmission Repair

February 22, 2012

A 9-step process for DIY diesel transmission repair, way to save money, and the benefits and drawbacks of a diesel transmission repair specialist.

Diesel Transmission Repair

Doing a diesel transmission repair yourself will save you a lot of money. Even if you are not looking to repair your diesel transmission, knowing some of the steps involved will help you determine if the garage is doing what needs to be done.

  • Lift the vehicle. Getting at the transmission on a diesel engine will mean that you need to lift the vehicle off the ground. These transmissions are massive, and weigh hundreds of pounds. Once the vehicle is on a lift, you need to use a hoist or a large transmission holder to stabilize the transmission
  • Disconnect linkage and drive train. Disconnect the drive train going into the transmission and let it hang freely. Remove the linkage to the shifter and disconnect from engine flywheel. Once that has been completed, you can drain the transmission fluid completely
  • Remove the transmission. Loosen the bolts that hold it to the frame. Make sure the transmission lift is directly under it, and touching the bottom of the transmission. As you loosen the bolts it will rest on the lift
  • Remove transmission housing. Using a long handled socket wrench, remove the transmission housing to be able to work on the interior gears. Place these bolts in a safe spot that's free from dirt. Scrape off any sealant and gaskets on the housing with a screwdriver, or a chisel wrapped in a cloth or one with a rubber tip
  • Change the gearing. Most of the diesel transmission problems are related to heat build-up. As the transmission works, it's causing friction, which causes heat. Not having enough coolant or lubricant in the transmission will cause the gears to overheat, crack, wear or slip. Changing the gears requires loosening the gear holder and replacing with newer gears
  • Clean out the old metal. With a clean rag, wipe out the inside of the transmission to remove any metal shavings that might still be there. These shavings can cause damage to the new gears very quickly if you leave them there
  • Place the gasket on the cover. Once everything is back in place, and the inside has been cleaned out, place a gasket on one side of the transmission housing. After that, run a bead of transmission sealant along the entire perimeter of the other side
  • Put the transmission together. Slide the two sides together and secure with the bolts you took out. You also have the option of using new bolts if the others are corroded or stripped. Use thread locking adhesive and tighten
  • Install the transmission. Place the transmission back on the vehicle in the reverse order you took it off. Remember to fill with transmission fluid once all the connections are made

How to Save Money on Diesel Transmission Repair

If you take your diesel engine powered vehicle into the local dealership or a national transmission chain shop, you are likely to be presented with a price that will run you several thousand dollars. While repairing or replacing a diesel transmission is never going to be really cheap, there are ways to save some money.

Fix Small Problems Right Away
While properly maintaining the transmission in your diesel vehicle will help you to avoid most transmission problems and repairs, you may occasionally start to notice issues with jerking or shifting. At the first sign of a transmission problem, don't delay and take your vehicle in for service immediately. Often, minor transmission problems can be fixed quickly and rather inexpensively; however, if you wait too long, a small incident will become a big problem and usually cost a lot more money.

Consider Independent Transmission Shops
Rather than taking your diesel car or truck to the dealership or a national transmission chain shop, consider visiting smaller independent transmission repair centers. These smaller independent shops usually provide quality repair service on transmissions and do it for about 30 to 40 percent less than the dealership or a national chain repair shop.

You can find reputable independent transmission shops in your area by visiting local auto parts stores and asking employees that work there about shops to visit. Also, consider visiting a couple of used car dealerships in your area and asking which shops they use for transmission repair work. Used car dealers often send cars out for transmission service and certainly know where to find the best deals. Finally, don't forget to ask friends and family members, as they may know reputable and affordable shops that work on transmissions as well.

Look for Coupons and Promos
Don't forget to check your local newspaper for transmission repair shops offering coupons or promotions on transmission repair and service. Often, local transmission shops place advertisements in newspapers in an attempt to draw in new customers. Even a modest 10 or 20 percent discount on an expensive transmission repair or replacement can result in saving a few hundred dollars.

Find a Local Vocational School
If your area has a local community college or vocational school that teaches students transmission repair, you can save a lot of money by taking your car to the school for repair. Most of these schools will only charge you for the parts used in the repair and not charge any labor at all. While the students that perform the actual repairs may not be very experienced, the teachers and instructors that are supervising the repair are usually very experienced mechanics. You'll not only save a lot of money on a transmission repair, you'll be helping to give a new generation of mechanics and technicians much-needed experience.

The Pros and Cons of Going to a Diesel Transmission Repair Specialist

While there are certainly many repair shops and service centers that can work on transmissions, most mechanics and technicians that work at local transmission shops specialize in transmissions for gas powered vehicles. For your diesel vehicle, you should always seek out qualified mechanics that specialize in diesel vehicle repair.

Advantages of Diesel Transmission Repair Specialists
Choosing a vehicle repair service center that specializes in diesel vehicles or diesel transmissions will always result in a better quality repair than choosing a service center that does not. Diesel engines and gasoline engines are considerably different in design and the transmissions used in conjunction with these engines are different as well.

Certified mechanics at service centers that are qualified to work on diesel and transmissions are usually factory trained. They are instructed on the latest methods and techniques for quick diagnosis and repairing problems with diesel transmissions. If you drive a diesel pickup truck that uses a Cummins, Duramax or Power Stroke diesel engine, going to the dealership or a diesel transmission specialist will result in quicker repair turnarounds and will probably wind up costing you less money in the long run. While other garages may quote you a lower price, their inexperience with your vehicles' particular diesel engine and transmission will probably result in more labor hours charged and more return visits.

Disadvantages of a Diesel Transmission Repair Specialist
There are many types of diesel transmission repairs that almost any decent mechanic or repair shop can perform for you. In fact, there are many types of diesel maintenance and repairs that you can do yourself. If you only need to change the transmission fluid or transmission fluid filter in your diesel vehicle, these are tasks that you can easily do on your own and save yourself from expensive repairs. In fact, if you purchase a car repair manual for your diesel vehicle, such as those made by Chilton or Haynes, you will find that there are many transmission related repairs that you can make yourself.

Shops that specialize in transmission repair on diesel vehicles usually charge a lot of money for their services. While taking a diesel vehicle with a damaged transmission in for a transmission rebuild or replacement may be a good task for the specialty shops, other types of repairs are best made by general mechanics or shops. Before you go to a diesel transmission repair specialist and spend a lot of money, you should take your vehicle to a local shop before paying the specialist the big bucks.