Sunday, August 20, 2017 Detailed Auto Topics
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Failure of an automatic transmission is one of the largest repairs most people suffer. Sometimes an automatic transmission dies suddenly, with no warning. More often, subtle signs precede the failure of our transmission. Learning to recognize these warnings can prevent a breakdown and greatly reduce repair costs.

In the previous segment of this article, we discuss shift-timing and slipping. Either issue suggests a problem with the automatic transmission. Other less subtle signs also provide clues. These symptoms normally occur after problems begin. Taking note of these items may not prevent a problem, but likely will reduce the impact.

A delayed engagement in the automatic transmission

A pause before moving is a delayed engagement

Shifting into drive or reverse, we expect our vehicle to start moving. Movement occurs almost instantly, unless a problem develops. The automatic transmission remaining momentarily in neutral, after we shift into gear, means we have a delayed engagement. The delay may last a few seconds or longer. Often the delayed engagement will be most noticeable, on the first drive in the morning.

A delayed engagement is a type of slip in the automatic transmission. The clutches or bands, which allow the vehicle to move, do not operate instantly. This often occurs when the internal seals wear or become hard from infrequent fluid replacement. Seals on the engaging mechanisms, allow fluid pressure to flow passed. Rather than applying the clutches or bands, the fluid returns to the pan. After a delay, the fluid pressure applies the mechanisms and our vehicle moves.

We must avoid racing the engine when a delayed engagement occurs. Increased engine speed produces friction and can damage the clutches and bands. Should the automatic transmission engage while we race the engine, even more damage may occur. Allowing time for the transmission to engage prevents needless damage.

Automatic transmission fluid contains conditioners that help to keep seals pliable. In time, we deplete these additive through use. Replacing the automatic transmission fluid and filter helps prevent hardened seals and a delayed engagement. After the problem occurs, servicing the transmission fluid and filter may help. With a delayed engagement, we must eventually replace the seals and acting sooner limits other damage.

Noises from our automatic transmission

A noise that changes when the transmission shifts, is a problem

Some failures in an automatic transmission produce an audible warning. Many things can produce noise, but a sound that changes when we shift into gear suggests a transmission problem. A whir or whine noise is common. If we hear these when sitting still, a plugged filter is a possibility. A restriction to the fluid flowing through the filter often produces a noise.

restricted filter is a problem, but it is also a symptom. Debris from the transmission has plugged the filter and the source of the contaminants is the problem. A plugged transmission filter usually means severe damage.

An automatic transmission can also produce scraping or roaring noises when we drive. An example is a whine in first and second gear, which goes away when the transmission shifts to third. This type noise most often means the planetary bearings have damage.  A bad bearing will cause extensive damage if we do not correct it. Noises that change or go away after the automatic transmission shifts, mean we should stop driving and have the vehicle checked for problems.

Automatic transmission fluid leaks

A leak may be a problem or a symptom of a problem

Fluid leaking from our automatic transmission can show a problem or produce a failure. Transmission fluid is the life blood of an automatic transmission. A leak reduces the fluid available and can cause many problems. Any fluid leaking from a transmission is serious and repairing it immediately, prevents many problems.

A fluid leak may also be a symptom of a transmission problem. An internal leak or an improperly installed filter may cause aeration of the automatic transmission fluid. This introduces air into the fluid. As the fluid expands, it may overflow from the vent or dipstick tube.

Overheating may also cause fluid to overflow from our transmission. Automatic transmission fluid that is over heated, normally has a burned smell. Transmission fluid also darkens when overheated. Black and burned fluid means problems exist.

 

Confirming automatic transmission problems

Paying attention to symptoms may prevent a major breakdown

With a few simple tests, a professional shop easily diagnoses transmission failure. We can learn if an automatic transmission problem is internal or caused by an input, with a pressure test. This measures the internal pressure in the transmission and shows if it rises and falls when it should.

On automatic transmissions with a removable pan, looking inside will show debris and metal particles associated with failure. They may remove and cut the transmission filter open to show what is inside. To know the full extent of damage, we may need disassembly. Disassembling the transmission to confirm failure is not necessary.

We must research and find a trusted shop, before we permit any disassembly of the transmission. After they remove and disassemble an automatic transmission, all diagnosis is over. After disassembly, most other shops will no longer accept a transmission for repair.

The advantage of recognizing the early warning signs is, we have time to find a trusted repair facility. This saves a huge amount of frustration and money as well.





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