No Need to Drain This Stick Shift’s Oil
Question: I have a 1979 Ford Fairmont with a four-cylinder stick shift. Why didn’t Ford put a drain plug on the transmission so I could drain out the old oil? I think it should be changed sometimes.--J.
Answer: Auto manufacturers do not always recommend changing the oil in a manual transmission, because the oil is sealed and not subject to contamination. In your case, Ford does not recommend regular oil changes. You should also check your owner’s manual.
Periodically, you might inspect the seals and gaskets around the transmission to make sure they are not leaking. The transmission has a filler opening, and you can check for the proper oil level by removing the plug and filling the case with the proper gear lubricant.
Q: My 1985 Pontiac Trans Am has experienced several failures of its four-speed overdrive transmission. The failures occurred every few thousand miles. Can you supply any information about this transmission?--L.S.K.
A: The four-speed overdrive transmission in your Pontiac is designated as an MD-8 by GM but is better known as a 700R4 in the transmission-repair industry, where it is famous.
The 700R4 suffers from many problems, but the most noteworthy is a vulnerability to early failure in a rear planetary gear assembly. A ring gear, which is a large ring with gear teeth on its internal circumference, was made of a soft steel that prematurely wears out.
Under high heat conditions, the ring gear breaks down, causing concurrent failure of the planetary and sun gears that are packaged inside the circumference of the ring gear. The problem was partially solved by GM when it introduced a new case-hardened ring gear.
But even the case-hardened gear is subject to failure. That’s because the 700R4 is subject to overheating in its rear gear system. Some remanufacturers of this transmission modify the oil-pressure control system to boost oil pressure, according to experts at Northeastern Transparts Inc. of Buffalo, N.Y., a major remanufacturer of transmissions.
In addition, GM has warned in service bulletins that the transmission cooling section in the radiator can become plugged with metal particles. That can mean repeated failures due to overheating, which may be happening in your case.
Q: The hand brake on my 1985 Toyota Corolla is giving me problems. When I want to disengage the brake, it is difficult to push in the little knob that releases the brake. Is there anything that can be done?--M.H.
A: The hand brake relies on a ratchet system to lock the brake lever in place. If the teeth don’t have any lubrication, they can become difficult to operate. You may want to try to lubricate the entire system, using a graphite spray that will reach inside the mechanism.
