Transmission Services and Rebuilding

transTransmission Signs and Symptoms

Refuses to go in gear

Believe it or not, there are still quite a few people out there who practice the fading art of shifting manually, with a foot pedal and a “stick” gearshift, and who do so willingly.

Despite their somewhat simpler operation,  manual transmissions nonetheless have their share of things that can go wrong. One potential problem is that the transmission refuses to budge when you depress the clutch pedal and attempt to move the stick shifter.

It may happen when trying to get into first gear from a stop, or at any point up and down the assorted gears. Common causes include low transmission fluid, wrong viscosity (thickness) of fluid, or required adjusting of the shift cables or clutch linkage.

The nose knows when it comes to things being not quite right with your vehicle. Continue to the next page to find out how your olfactory sense factors into transmission diagnosis.

Burning Smell

If you get a whiff of burning transmission fluid, be advised it is definitely not the sweet smell of success. That’s because it may indicate your transmission is overheating. Transmission fluid not only keeps the transmission’s many moving parts properly lubricated, but it prevents the unit from burning itself up, by providing much-needed cooling.

In some vehicles, the transmission even has its own mini-radiator (an oil cooler) that circulates fluid to transport heat away from the transmission unit itself.

Common causes include low or inadequate transmission fluid, which can in turn indicate a leak or dirty fluid that needs changing.

If you thought your transmission was safe from wear at least while it was in neutral, the truth might surprise you. Look to the next page for the scoop on noises in neutral.

Transmission noisy in neutral

It seems intuitive that if you hear weird noises when the car should be shifting, that the transmission is acting up. But would you suspect it if things were going “bump” in neutral? Yes, it could be the transmission.

Such sounds could have a simple and inexpensive solution — as with many of the problems on our list, adding or replacing the transmission fluid sometimes does the trick. Bear in mind that as is the case with engine oil, different vehicles do best with the specific formulation called for in the owner’s manual.

Alternatively, lots of noises from the transmission while it’s in neutral could signal something more serious, like mechanical wear that will need the replacement of parts. In this case, common culprits are a worn reverse idler gear or worn bearings, possibly coupled with worn gear teeth source:  procare.com

Losing control while driving is never a fun experience. Find out on the next page how a bum transmission could have a car “slipping” toward disaster if not repaired in time.

Gears Slipping

In a normally functioning  transmission, the car stays in the gear you designate, or that the computer designates for a given RPM range, until you or the computer initiate a gear shift.

But on a transmission in which the gears slip, the car can spontaneously pop out of the gear it’s in while driving and (in a manual) force the stick back into neutral source:  

This is unnerving at best and potentially dangerous at worst: when you mash the gas pedal to avoid an out-of-control vehicle, the last thing you want is a transmission that doesn’t get power to the wheels. No need to scratch your head over whether this is trouble or not: if it happens, you know it’s time to have your transmission examined.

Our next trouble sign might seem like a real “drag” if it happens to your vehicle, but its fix is often not so complicated — see what it is on the next page.

Leaking Fluid

Leaking transmission fluid is probably one of the easiest ways to identify that your transmission needs attention. Automatic transmission fluid is vital to your car’s shifting capabilities, so a little fluid on your driveway can quickly turn into a major problem. Automatic transmission fluid is bright red, clear and a little sweet-smelling when everything’s working correctly [source: AAMCO. When you check your automatic transmission fluid, make sure it’s not a dark color and that it doesn’t have a burnt smell. If it is, you’ll need to take it to a mechanic and have it replaced. Unlike your car’s motor oil, the transmission doesn’t really consume or burn up any fluid during use, so if you notice you’re running low on fluid, then it’s definitely leaking out somewhere.

If you have a manual transmission, checking the fluid levels may not be as easy as simply lifting the hood and reading a dipstick. Manual transmission fluid has to be checked right at the transmission case — usually through the fill plug. Again, if you suspect your transmission is losing fluid, have a mechanic locate the leak and have it fixed.

If your fluid level is good, there’s another easy way to know if there’s something wrong with the transmission: go on to the next page to see how you can find out if your transmission is having problems — without even having to pop the hood.

Check Engine Light

Leaking transmission fluid is probably one of the easiest ways to identify that your transmission needs attention. Automatic transmission fluid is vital to your car’s shifting capabilities, so a little fluid on your driveway can quickly turn into a major problem. Automatic transmission fluid is bright red, clear and a little sweet-smelling when everything’s working correctly When you check your automatic transmission fluid, make sure it’s not a dark color and that it doesn’t have a burnt smell. If it is, you’ll need to take it to a mechanic and have it replaced. Unlike your car’s motor oil, the transmission doesn’t really consume or burn up any fluid during use, so if you notice you’re running low on fluid, then it’s definitely leaking out somewhere.

If you have a manual transmission, checking the fluid levels may not be as easy as simply lifting the hood and reading a dipstick. Manual transmission fluid has to be checked right at the transmission case — usually through the fill plug. Again, if you suspect your transmission is losing fluid, have a mechanic locate the leak and have it fixed.

If your fluid level is good, there’s another easy way to know if there’s something wrong with the transmission: go on to the next page to see how you can find out if your transmission is having problems — without even having to pop the hood.

Grinding or Shaking

Depending on whether you have a manual or  automatic transmission, your car may respond differently when your transmission isn’t working correctly. As noted in a previous section, with a manual transmission, a common sign of trouble is a grinding sound or feeling when you shift into a new gear. If you fully engage the  clutch, shift and then hear a grinding sound, you may have a worn clutch or you may just need to have it adjusted. Or perhaps one or more of your transmission’s gear synchronizers, or synchros, is worn out or damaged. Grinding gears can be caused by a number of different factors.

For automatic transmissions problems, you’ll most likely feel the car shimmy into each gear rather than the typical almost unnoticeable shifts, or the transmission will make a jarring transition into the next gear. Both are signs that your transmission needs attention. If you notice anything other than a smooth transition between gears, then you might need to have your automatic transmission looked at for adjustments or repair.

But feeling transmission problems aren’t the only way to use your senses. Go on to the next page to see what sounds you should be listening for as well.

Lack of Response

Transmissions are designed to go into the correct gear every time, so when they hesitate or refuse to go, it’s a sure sign there’s something wrong. With manual transmission problems, you may notice after shifting into a gear that the car’s engine will rev up, but the car won’t be moving as quickly as the engine is running. In this case, a worn-out clutch or more serious transmission problem may be occurring.

Automatic transmissions have the same lack-of-response problem, but will usually manifest the issue while engaging the “Park” or “Drive” selection. The car should shift quickly into either of these modes, but if your transmission hesitates to go into either one, then it’s likely there’s an issue with the transmission.

For more information about transmissions and other related topics, follow the links on the next page.