My car is leaking transmission fluid – I can’t diagnose the leak

ANSWER : Based on the NHTSA database covering consumer complaints, as well as government mandated recalls and factory service bulletins, for your specific year, make and model, I do not see evidence of widespread complaints about transmission fluid leaks. Such leaks are, in fact, common in transmissions made by any car company, particularly if the transmission is older than say 10 years. There is a manual shaft seal, oil pan gasket, output shaft seals, case seals, torque converter seal (inaccessible) and so forth all of which are potential leak points on your transmission.

If you want to identify and resolve these leaks, certainly a certified Mechanic from YourMechanic could come out and perform a transmission leak inspection and let you know where the leak points are and what it will cost to resolve them.

ANSWER : This would depend on what the manufacturer recommends. Many manual transmissions do take automatic transmission fluid. If your transmission has ATF in it, it is very likely that it is supposed to have that in there. If not, it is likely that the transmission would not function properly with the wrong fluid. Many manual transmissions will also take engine oil as a lubricant. The best way to know for sure is to check your owner’s manual or call your local General Motors dealership to inquire.

ANSWER : That’s a very good question. The reason they have gone with no dipsticks is because they don’t want people messing with transmissions other there at the dealership. Some cars went through that a couple of decades ago. They make it a very involved, convoluted process all through, in order to change the fluid on these modern cars. They have special adapters you have to put. Some of them have to have scan computers in order to read the data and what’s in there, and then be able to change it. A lot of these companies claim that this new fluid is the "lifetime" fluid.

Most new use synthetic fluid can last a long time but any fluid is going to get dirty and wear out over time. I would change it at least every 80,000 – 100,000 miles but if you’ve got one that is really hard to change, you are better off hiring a mechanic to do it.

On some of the cars, it would be too hard for the do-it-yourself because of all that equipment you need. The professional mechanics already have that. Just call any good mechanic, like one from YourMechanic, and they will be able to perform a transmission fluid service for you.

ANSWER : Hi there. First off, the transmission and brake system are separate and utilize different oils. If you’re leaking oil from the slave master cylinder (which is a clutch component), it’s transmission fluid that might be leaking. If you’ve been told that this has been damaged, there really isn’t a way to stop the leak without fixing the damaged component. You might want to have a mechanic replace your clutch slave cylinder before it completely breaks.

ANSWER : Generally, there are only a few places for leaking transmission fluid to go to since it does not burn off inside the transmission, unlike motor oil inside an engine. You have already ruled out the possibility of an external leak somewhere because of the lack of any visible signs of leaking.

A ruptured modulator can allow the fluid to be sucked into the engine (this is uncommon), or the fluid may have leaked into the transmission cooler. Another possibility may be a leak that is only active when the vehicle is in use or during times where hydraulic pressure is present in the transmission, such as while driving.

Try looking underneath the car and clean the surface areas under the transmission with a brake cleaner to get rid of any grease or oil spots. After cleaning, take the car for a drive. When you return, look underneath the car to see if you can spot any visible signs of fresh fluid leaking from under the transmission.

It is recommended that you get a certified technician, such as one from YourMechanic, to come to your location and determine the cause of the transmission leak.

ANSWER : This kind of reaction is often a sign of low transmission fluid or a faulty transmission control solenoid. As you know, automatic transmissions use pressurized hydraulic fluid to change gears. Every time a gear change is required, the car’s computer activates a transmission solenoid, which directs transmission fluid into the valve body to engage the correct gear. When this is faulty or not working properly, this can cause a delay in gear shifting or in some cases cause the car to not shift at all. This type of problem is amplified any time the transmission is low on fluid creating a drop in hydraulic pressure. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your vehicle.

ANSWER : From the description you’re giving me, I’m not sure. I know many Fords, including my F150, have a circular seal type bell housing inspection cover near the transmission. Fluid pooled in this area generally indicates an engine oil leak from the rear main seal or a transmission leak from the front pump seal. The only way to know for sure is to have your truck’s transmission leak inspected firsthand by a professional. The team at YourMechanic is an excellent option since we make house calls.

ANSWER : This sounds like a faulty speed sensor problem. Most cars have two speed sensors (one monitors input shaft and one monitors output shaft) which tell the computer what the gear ratio is of the transmission while in use. If either of these are not working properly, they will cause the computer to shut the car off for safety reasons. I would suggest having an expert from YourMechanic come to your home to diagnose your stalling issuee and help you repair it.