What Is Done In A Transmission Service?

John is a fervent writer, gamer, and guitar lover. He is a erstwhile automatic-transmission repairer, welder, and hobbyist game developer.

Servicing an automatic transmission is a part of vehicle maintenance that ofttimes gets forgotten—or worse, intentionally avoided. As with many things related to automatic gearboxes, servicing is non the relatively simple task that servicing an engine is, and it tin scare a lot of people (including mechanics), especially in European countries where automatics are less prevalent.

Knowing how often to service the fluid is part of the battle, equally information on what to do is often hard to notice in the standard vehicle documentation. This matter is further dislocated by sure manufacturers such as BMW placing optimistic "Lifetime Oil" stickers on their transmissions and insisting you should exit information technology solitary. The truth of the "lifetime oil" probably lies in the fact that the manual itself will fail before the oil degrades to the point where it causes a failure, just regular servicing can assistance prevent automated transmission faults from occurring, and will likely extend the life of your transmission.

As a dominion of thumb, however, you should service your transmission every 30,000 miles.

Doing It Yourself

Before we get into the details of how to service your automatic manual, be aware that I am referring to a fully automatic transmission (run across this commodity on transmission types for the differences). Also, please sympathize that there are many, many models of transmission, and many variants of those models. I can't provide exact instructions for every manual in this lone hub, merely hopefully you'll have enough to go on from the information below.

How to Service an Automatic Transmission Yourself

Hither are some steps you tin can take to service the automatic transmission in your car.

Things Yous Might Need

Spanners/Allen Keys
Funnel
Oil Pump
A Tray for Catching Oil
Manual Fluid

Determine Your Manual'due south Levelling System

The first thing you lot need to do is establish what kind of levelling system your manual uses. There are three master ways in which automatic transmissions can be levelled with the correct amount of oil.

Dipstick
Levelling Bung
Levelling Tube

The easiest of these (and unfortunately the least mutual) is the dipstick. If your manual has a dipstick and then you level the transmission in the same way you lot level your engine oil; by dipping the transmission and adding more than fluid until the level is correct.

If your transmission uses a level hurl, you lot volition demand a style of pumping the fluid into the transmission from underneath, and yous will likewise need something to catch the oil.

The level bung will be somewhere on the transmission at a higher betoken that the drain hurl, and the levelling process involves pumping transmission fluid into the box until it starts coming out of the levelling bung.

A level bung will be higher than the drain bung, often facing out rather than down. — A level bung volition be college than the drain hurl, often facing out rather than down.

BA Transmissions

A levelling tube often sits in the hole through which the transmission should be drained, and must be removed in order to drain the oil.

John Bullock

Finally, we have the levelling tube. The levelling tube works in the same mode every bit the levelling bung in that you pump fluid into the manual until it starts to come back out. The problem is that the levelling tube is often inside the drain hurl, pregnant you have to check whether there is enough fluid using the same hole y'all are filling it through. Needless to say, this is the most hard (and messiest) way of levelling an automatic transmission.

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Draining Your Automatic Manual

Understand that, in a typical transmission oil service, you will only exist changing about two-thirds of the oil in your transmission. Gravity can simply go so much of the fluid inside; the residue remains in places like the transmission cooler, the torque converter, and various places inside the transmission itself. You can take your transmission "power flushed" to exist sure you're getting a consummate oil alter, but that requires specialist equipment and is non something yous're probable to be tackling yourself (unless you lot ain a garage).

With that in mind, yous will need to establish which is your drain hurl, find something to catch your quondam manual fluid (and have a responsible way of disposing of it), and the means to become under your vehicle.

If your transmission employs a dipstick or a drain bung, simply place your waste oil receptacle so that information technology will grab the oil and undo the bung. If your manual uses a levelling tube, you volition need to undo the levelling bung commencement, and so air current out the tube too.

Leave your transmission draining until the oil coming out slows to a trickle. Y'all tin can leave it longer if you wish, simply be aware that information technology will go along to trickle out for hours if you permit it. If yous really want to be thorough, y'all could leave it overnight to get equally much oil out every bit you can, but given that the best y'all tin hope for is nonetheless effectually two-thirds of the total transmission fluid, it'south probably not worth it leaving for also long.

There are many specifications of transmission fluid. Make sure you have the right one for your gearbox. — There are many specifications of transmission fluid. Make certain you have the right one for your gearbox.

Hemmings

Levelling Your Manual Fluid

One time yous have drained the oil to your satisfaction, refit the sump bung (supervene upon it if y'all want to be really thorough), unless your transmission uses a levelling tube, in which case simply replace the tube.

Begin refilling your transmission with fresh fluid, ensuring the oil y'all're using is the right specification for your particular manual. If you're filling from underneath, pump the oil in while watching for the oil coming back out. If, in the form of filling the manual, y'all are obstructing the levelling hole/tube, pause every so often to check that the oil is not trying to come up dorsum out. If your manual has a dipstick, simply cascade the oil through the dipstick using a funnel.

Once the oil is levelled… you're nigh washed.

You see, when an automated transmission is running, it pumps the transmission fluid effectually the manual system, including the libation and torque converter. This is relevant to yous because when the transmission is running, the oil level drops significantly as the oil is taken upwards into the system. It's the oil level while running that y'all demand to work with.

So. Once the oil is levelled, make sure your vehicle is in park, fire up the engine, and so exercise it once again. This time, once the oil is levelled, y'all're done. You tin can put everything back together and clean up the mess you inevitably made.

If possible, you should bulldoze the vehicle, existence sure to get all the gears, and then bank check the level once again to be sure. Yet, as long as the level was non sitting on the minimum when checked, it should exist fine.

Other Things You Should Know

There are some other steps in the procedure that you should also pay attending to.

Stay on the Level

It seems obvious, but it's worth pointing out that in order to get an accurate reading of the oil level, your vehicle needs to be as shut to horizontal as possible. This means no sloped driveways, and no jacking the forepart of the automobile up.

Filtered?

Changing an automatic manual filter will, generally, involve removing the sump entirely, and so if you're not comfy exposing the innards of your transmission, y'all may want to get out the filter alone (or take it to a transmission specialist). Of course, this just applies to transmissions where the filter is accessible without taking the whole gearbox apart!

Temperature

There is an optimum temperature for the transmission fluid you are putting into your transmission. It varies from model to model simply is ordinarily around forty°C. Generally you'll exist fine filling your transmission at lower temperatures, just be sure not to overfill.

Manual dipsticks will often have "hot" and "cold" markers. You'll have to utilise your judgement as to which stop of the spectrum your oil is at.

No Dipstick?

Some transmissions with dipstick tubes do not actually accept dipsticks within them (Mercedes-Benz are guilty of this). In these cases, you'll demand to purchase (or infringe) a compatible dipstick to bank check your level.

How Much Oil?

It is possible to wait up how much manual fluid your gearbox should take using services such as Haynes, or Autodata. Do not do this. I can't stress plenty how much variation you can get in automated transmissions. Perchance you lot didn't bleed every bit much as you idea. Perchance the previous owner fit a larger cooler, increasing the oil capacity. Always level your transmission properly, don't trust technical information capacity figures.

Filling Through the Dipstick Tube

While filling through a dipstick tube is undoubtedly the easiest way to get oil into your transmission, it can be a picayune awkward to bank check the level. The oil tends to cling to the insides of the tube, causing the showtime few dips to be wildly inaccurate. I find it all-time to permit the oil settle for a few minutes, then dip information technology a few times until the level is consistent. If one side of the dipstick shows a different level to the other, ever become with the lower side.

This article is accurate and true to the best of the author'due south noesis. Content is for informational or entertainment purposes simply and does not substitute for personal counsel or professional advice in concern, fiscal, legal, or technical matters.