Transmission pump: What it is and what happens when it goes bad?

An automatic transmission needs pressurized hydraulic fluid/transmission fluid in order to function. This pressure is created by the transmission pump which lives in the front of the transmission case, and is operated by the torque converter. When the engine is running, the torque converter hub spins the transmission pump, which draws fluid up from the pan, through the filter and into the pump where it gets pressurized and distributed to the valve body, torque converter, clutches and wherever else it’s needed.

Need a replacement transmission? Get an estimate for replacement transmissions and local installation. Look up your transmission model by vehicle make and model.

What Transmission Do I Have?

Types of transmission pumps

A gear driven transmission pump has a fixed output and is a very common pump in most vehicles. A vein type transmission pump has a variable output, which means that the pressure/psi this pump puts out can be controlled and reduced if the computer sees fit. These are becoming quite common in modern, multi-speed transmissions where controlling every action of the transmission can result in improved efficiency and performance. Both of these transmission pump types can be converted to off – axis pumps for more compact transaxle designs.

Symptoms of a bad transmission pump

Transmission slipping – Since an automatic transmission requires pressurized hydraulic fluid to change gears, a failing transmission pump may not be able to create enough pressure, and thus the transmission will not be able to hold a gear and slip into neutral.

Noise – If the transmission pump is going bad, it won’t be unusual to hear a whining noise coming from the front or side of the transmission. The noise will generally increase as the engine speed increases.

Fluid leaks – There are multiple seals where the torque converter contacts to the pump. If one of these seals goes bad, you may see a transmission fluid leak near the front of the transmission.

Failure to proceed – If a transmission pump has completely failed, it won’t be able to create the hydraulic pressure needed into turn the drive wheels. Therefore, you’re not going anywhere.

How to solve transmission pump problems

If you’re lucky, the problem will be caught just as it starts and you can replace the transmission pump and be on your way. But if you’re not lucky enough to experience the best case scenario, then more internal damage can occur as the transmission pump goes bad. Should this be the case, you’ll also have to either rebuild or replace your transmission.

How much is it going to cost to fix my transmission?

Unfortunately, the problem described here will require the removal and disassembly/partial disassembly of your transmission. Given the labor time involved to remove6 the transmission from the vehicle (this is not a simple task), most repair shops will recommend that you go ahead and rebuild the entire transmission while it’s out. Since they already have to tear it down, it sort of makes sense to spend the extra money to do that. After all, you should get a lot more mileage out of your transmission once it’s rebuilt. And since they’ve already got the transmission apart, might as well, right?

Things to consider with a transmission rebuild

You’re the test driver – Most transmission repair shops and mechanics will only put a few miles on your vehicle to make sure the transmission works. But it’s not uncommon to experience transmission problems during the break-in period.

Everything might not be fixed – Most mechanics and transmission repair centers don’t have the equipment necessary to perform a thorough inspection on hard parts like gear sets, clutch drums and valve bodies. This means that your rebuilt transmission could actually have small cracks in key parts that aren’t visible to the naked eye. As time and mileage progress, these cracks can grow and create an even larger problem. Similarly, a slight warp in the valve body can seriously impact shifting performance over time.

Warranty – Although most mechanic shops and transmission repair shops will warranty their work. That coverage is usually only good at the shop or franchise that did the work. If you travel out of town and suddenly experience transmission problems, you’ll be on the hook for any transmission repairs unless you pay to have your vehicle towed back to the shop that did the work.

Quality – Nearly every time you get a transmission rebuild, all of the work is performed by a single technician. This may or may not be a good thing, depending on your point of view. But the end result is dependent on that technician’s level of experience working with your specific type of transmission. In addition, there is usually no standardized quality control checks at a mechanic shop. So an improperly torqued bolt or gasket that isn’t fully seated, might be overlooked and cause you major problems in the future.

Why a remanufactured transmission might be a good option

If you plan to keep your vehicle for as long as possible, then getting a transmission rebuild is certainly a viable option. However, a remanufactured transmission is a much better alternative. You’re getting as close to a brand-new transmission as it is possible. Companies like Street Smart Transmission also modify the transmission to correct all of the factory design flaws, allowing you to get a much longer service life from the transmission. You also get a 3-year/unlimited mile nationwide warranty, which allows you to get necessary repairs performed at any licensed repair shop of the country. So in terms of value for the money, a reman transmission might be the better way to go. 

Remanufactured transmission companies like Street Smart Transmission put each of their reman transmissions through a rigorous build process that ensures a quality product every time. It starts with nearly 100 trained technicians that specialize in different aspects of the build process. 

This remanufacturing process begins with the inspection team that test all of the critical components from the donor transmission to ensure that they meet the original equipment (OE) tolerances and specifications. The case, pumps, gears, shafts, valve body and torque converter are checked for hairline cracks, metal tensile strength, warping and other parameters. If any component fails to meet the required specifications, it’s discarded and replaced.

All the parts are then cleaned and sent to the appropriate stations on the assembly line for reassembly. Throughout the process, quality control managers inspect the build to ensure that it meets the desired specification. Any necessary modifications or upgrades that are needed to correct factory design flaws are also performed or added. The valve body is rebuilt and tested on a special dyno machine to ensure that it performs according to the specifications. All of the solenoids are also tested prior to installation.

Once the build is complete and passes its final quality control inspection, the newly remanufactured transmission is sent to the dyno room, where it’s tested on a special dyno machine using a proprietary software program called C.A.R.S. (Computer Aided Real-world Simulation). This cycles the transmission through a number of real-world driving situations, to ensure that it performs according to the factory specs. It also helps to break in all of the friction components, that way it’s completely tuned and ready to go once it’s installed.

Warranty – One of the benefits of buying a remanufactured transmission vs. a rebuilt transmission is the warranty. Street Smart Transmission for example, covers all of their reman transmissions with a 3 Year/Unlimited Mileage Nationwide Warranty (there is a mileage restriction for commercial vehicles). This covers parts and labor for transmission repairs performed by any licensed repair shop in the country. It’s also completely transferable if you ever decide to sell the vehicle. Compared to a mechanics warranty on a transmission rebuild, a remanufactured transmission warranty offers superior financial protection.

Need a replacement transmission? Get an estimate for replacement transmissions and local installation. Look up your transmission model by vehicle make and model.

What Transmission Do I Have?

Is a remanufactured transmission worth it?

If you plan to keep your vehicle for as long as possible, then getting a transmission rebuild is certainly a viable option. However, a remanufactured transmission is a much better alternative. You’re getting as close to a brand-new transmission as it is possible. Companies like Street Smart Transmission also modify the transmission to correct all of the factory design flaws, allowing you to get a much longer service life from the transmission. So in terms of value for the money, a reman transmission might be the better way to go.