Oil Pans In Automatic Transmissions: Types and Design Peculiarities, Common Issues, Tips On Pan Selection and its Replacement

In automatically shifted cars an oil pan services as a so-called storage for ATF, and ensures for a convenient access point to the transmission filter and fluid. For automatic transmissions (ATs) ATF is vitally important, as it lubricates transmission parts and prevents overheating, thereby avoiding early wear of the transmission unit.

Oil pans also play a significant role in protecting ATF from different contaminants. The pan’s magnet helps to gather any dirt or debris from the fluid. This structurally simple component also helps to cool down the fluid before it is transmitted to the main gearbox components directly involved in the process of gear shifting. Pans also help to avoid mechanical damages to AT units from rocks or other obstacles met on the road, prevents rustiness and ATF oxidation. Apart from the stock pan, there are numerous types and variations of this simple, but extremely important component. Some pans can even enhance operational capacity of your AT unit. For instance, deep pans ensure better cooling, as your transmission can storage more ATF.

That’s how a standard transmission pan looks like

On average, AT units contain a bit more than 11 liters of ATF, while more powerful cars have the fluid holding capacity of up to 34 liters! Almost half of ATF is stored in the pan, while the remaining amount performs its direct lubrication functions within the AT unit itself. If transmissions need more fluid it means that these units operate more intensively for the purpose of dealing with the car’s engine power. ATs with more fluid have greater cooling characteristics.

Common Issues

An automatic transmission is considered to be one of the most frequently serviced and repaired components in modern cars, as numerous auto repair businesses mainly focus on transmission repair services. Transmission pans, despite their simple designs, also can get out of order in a number of ways. Transmission repair specialists point out the following possible issues in the oil pan:

• When driving at high speeds, the pan can be deformed or damaged by some objects (rocks or other road debris) encountered on the road that could lead to fluid leakages. This results in faulty gear shifting operation;

Damaged transmission pan

• Pan gaskets may change its positioning or get cracked because of the wear-out, resulting in ATF leakages;
• Not tightly screwed up pan bolts or drain plugs may also lead to fluid leakages;

Leak

How to prolong the service life of your oil pan

ATF pans can perform its functions properly for quite a long time, but it requires compliance with some basic maintenance measures:

• Do not use cork gaskets and RTV sealants to ensure leak resistance of the pan. Cork gaskets are notable for unreliability and poor quality, thus they frequently wear out too early (it is recommended to use rubber gaskets). The use of RTV sealants, in turn, may lead to appearance of remaining materials (particles/debris) that contaminate ATF and end up on the pan surface;
• Make a careful examination of the pan gasket during ATF changes. If it has any signs of wear, it is better to replace it with a new one;
• Regularly check the pan surface for any symptoms of deformation or leakages;
• Do not forget to properly clean up the pan surface and the magnet that gathers metal chips;
• After the ATF change and the pan cleaning, make sure that you fasten the pan to the lower part of the AT in accordance with recommendations specified in the car manual. Otherwise, the pan can get damaged, and loose bolts can lead to leakages.

As the pan is exposed to any kind of impact from the external environment (i.e. the pan can be damaged by any obstacles that get under the wheels of your car while driving). Over time, the pan can become rusty or its surface may get some scratches and deformations, which will soon result in leakages. The same unfortunate result can be achieved, if the pan bolts get loose (or fall off). Thus, if you notice any signs of ATF leakages, it is highly likely that something isn’t right with the ATF pan.

If you ignore the abovementioned recommendations, it may lead to ATF shortages, which in turn, will significantly increase the wear of AT elements. As a result, your transmission won’t shift properly, and you will need an expensive repair.

Pan Selection

No matter how diligent you are in maintenance of your AT, and the oil pan in particular, but sooner or later you’ll have to replace your old pan with a new one. It is better to think about it before something goes wrong and find the necessary spare part in advance.

Manufacturers of powertrain elements and related spare parts can provide a wide range of varieties of the same transmission component to ensure the best performance characteristics, and the oil pan is not an exception. When it comes to replacement of your stock pan, you can choose from a wide range of pan options, depending on AT type, material used, ATF capacity, and cooling characteristics.

Ford C4 Steel Transmission Pan

Commonly, automakers equip their transmission solutions with stock steel pans. These pans are notable for their robustness and antirust qualities, and they turn out to be a budget-friendly option. In addition to affordability, it is very unlikely that the steel pan that you need will be out of stock.

GM TH400 Chrome Steel Transmission Pan

Frequently, you can also come across chrome pans made of steel with a chrome coating. In addition to much shinier appearance, chrome solutions are more maintenance-friendly (easy to clean) and more rust resistant than the abovementioned variant. But at the same time, chrome pans are a bit more costly than their steel analogs.

TH350 GM Aluminum Transmission Oil Pan Kit

Aluminum-made pans are considered by many experts as the best pan option available on the market. Aluminum pans have much better heat dissipation capacity and provide more efficient fluid cooling. In addition, this type of pans is much more robust and leak-proof than steel and chrome versions. But on the other hand, these pans are quite costly and it can be a challenging task to find the aluminum pan for a particular AT unit.

Other variations of pans

If you frequently expose your AT to severe operating conditions, it is recommended to consider installing a bigger oil pan with higher ATF holding capacity. Deep pans can store additional 2 or 3 liters of ATF. It may seem like a slight improvement, but for more powerful cars or cars frequently involved in towing/hauling operations deep pans can make a difference. More fluid helps to prevent overheating and to significantly prolong the service life of your AT unit. These pans also come in 3 versions (steel, chrome, aluminum).

Deep vs Conventional Pan

To enhance the cooling capacity of pans, some manufacturers include specials cooling fins or tubes in the structure of oil pans. However, such upgraded pans are more costly than standard stock or deep pans.

Allison transmission pan with cooling fins

GM transmission pan with tubes

Pan replacement

When it comes to the pan replacement, it should be noted that this procedure is not very complex and can be performed independently. Before starting the replacement procedure, it is required to ensure that you have all necessary new parts (gasket, pan, fluid) and tools (jacks, drain pan, screwdriver, etc).

Check out the video on how to replace the transmission pan

Now let us proceed to the pan replacement operation itself:

• First of all, lift your car with the help of the jack to get access to the oil pan area;
• Before fully removing the old pan, you have to drain all ATF. Some pans have a drain plug for this purpose, otherwise you will have to start unscrewing bolts one by one until ATF starts pouring out (do not unscrew all bolts before ATF is fully drained). Make sure that you use a drain pan to gather old fluid;
• Remove the old pan, clean up the area and replace the filter;
• Mount a new gasket to the new pan, and thread several bolts into it to keep it fixed. Ensure that the holes for the bolts in the gasket and pan match each other. Then insert and tighten remaining bolts in accordance with the recommendations from the manufacturer;
• When you finish the pan replacement, it is necessary to refill ATF. If you have no idea of how much fluid is needed for your transmission unit, you can find this info in the car manual (fill a bit less fluid than specified there);
• Start the car, shift through all gears, and let the fluid lubricate gearbox components. Check the ATF level with the help of the dipstick and add the missing amount of ATF.