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Discussion Starter #1
So I have a beautiful 08 Cobalt and it seems her transmission is going. I want to know how to remove it in a visual step by step guide. I bought a Haynes Repair manual but that does not have it. It has low power creeping up to 20 mph. My repair guy said it blew a rubber seal in the trans likely. He claims pressure builds up behind them to give them the strength to turn.

Fyi, I plan to keep her into old age as a classic car. Yes, maybe I am crazy. It is my first emotional attachment to a car. I cannot bring myself to sell her and it sealed the deal when no one would buy her on a trade-in.
 

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By low power, what exactly do you mean. Is the transmission slipping to the point it won’t accelerate? Just by what I first ready in your post, sounds like it’s low on power. Have you considered the catalytic converter may be clogged? I would need more info. But a clogged converter can cause the engine to have low power and cause difficulty accelerating and hard shifting. Also the engine may otherwise run fine out of gear.

A quick way to identify a catalytic converter problem is to use a scanner to read the oxygen sensor values. I know not all mechanics know how to read the scanner to identify this problem, but you may need to find someone who can if this is the problem. At least get a few opinions before you decide it’s the transmission.

The automatic transmission will shift oddly when the engine isn’t running correctly. When I first bought my Cobalt it would hard shift and lag sometimes during shifting. A tune up happened to be the fix for the problem I had.

Anyway, more information would be helpful. Like as in, is the transmission slipping, not going into other gears, vibrating. Also has the car had any maintenance done, like fluid and filter changes, tune up, etc.
 

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I'm not familiar with that. Can that converter be clogged with sludge from oil? My mechanic wanted to run some cleaner through the system. Now that you mention it I've researched cleaners as being a negative thing. They could cause a clog and damage multiple seals.
 

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I recall there being some kind of cleaner for catalytic converters. I used to see it at the auto parts store. But have never used it. I think it was supposed to be added to the gas tank. But if it’s clogged, it will likely just have to be changed. Unfortunately quite frequently, the engines in our Cobalts are know to burn oil. Many times it’s getting into the combustion chamber through the PCV system. Through the valve cover it flows into the intake and is burned during combustion. I know my car does this because it found oil inside the intake manifold and also on the throttle body. I did an induction cleaning to my engine, which in my case, helped with my fuel mileage. Had to change the spark plugs afterwards though.

So, in the case your engine has been burning a bit of oil over the years, it very well could have caused damage to the catalytic converter. It’s hard to say without testing. Most exhaust shops should be able to test your converter and verify if it’s bad or not. They should not charge very much to do this. I always send cars to a local exhaust shop that I trust to verify a suspected bad converter so not to jump to conclusions and waste my customers money. Something to consider though. I believe they charge about $50 to do the check on most cars. Not sure what other shops charge to do this.
 

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By low power, what exactly do you mean. Is the transmission slipping to the point it won’t accelerate? Just by what I first ready in your post, sounds like it’s low on power. Have you considered the catalytic converter may be clogged? I would need more info. But a clogged converter can cause the engine to have low power and cause difficulty accelerating and hard shifting. Also the engine may otherwise run fine out of gear.

A quick way to identify a catalytic converter problem is to use a scanner to read the oxygen sensor values. I know not all mechanics know how to read the scanner to identify this problem, but you may need to find someone who can if this is the problem. At least get a few opinions before you decide it’s the transmission.

The automatic transmission will shift oddly when the engine isn’t running correctly. When I first bought my Cobalt it would hard shift and lag sometimes during shifting. A tune up happened to be the fix for the problem I had.

Anyway, more information would be helpful. Like as in, is the transmission slipping, not going into other gears, vibrating. Also has the car had any maintenance done, like fluid and filter changes, tune up, etc.
This is so true. The 4T45E tranny along with GM’s 4T40E and 4T65E are VERY susceptible to slow shifting and “surge slip” conditions. GM has a tsb on the issue. Essentially a dirty maf sensor and cylinder head carbon deposits will give the incorrect calculated engine load reading to the TCM and will cause the transmission to shift funky. With these cars any type of misfire or engine performance issue can cause the tranny to act weird. Clogged or somewhat failing cat converters can definitely cause engine performance issues and secondary transmission shifting issues.
 

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Just as an example. I did an induction cleaning to help remove the oil build up that was coming through the PCV system into the intake manifold. Anyway, after doing it, that obviously soaked the spark plugs with cleaner and junk stuck in the engine. When I put the car into gear it caused it to hard shift. And only after cleaning the spark plugs did it shift smoothly. It was weird since the cleaner was not sprayed into the MAF sensor. But the dirty plugs reducing the engine power caused the trans to hard shift.

The same kind of condition happened in my Lincoln Town Car. For the most part it would shift normally. But sometimes it did some weird things. I had decided to replace the ignition coils, plugs, and wires. Afterwards it shifted smoother than it had the whole time I had owned the car. So in that instance, it made a world of difference.

I have had many customers come in thinking the transmission was going out just to find out it was some sort of drivability problem. The engine going into limp mode is sometimes the cause. But will usually set a check engine light or have a message on the dash display, like saying engine power reduced or something to that effect.
 
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