Posted: 1/28/2011 2:47:14 PM EDT
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OK I have a 1998 chevy lumina, with a 3.8L, and 95K miles on it. Ever since I got it a few months and 10K miles ago it's shifted rough and will hang up sometimes in the upper RPM's. I checked the trans fluid and I see that it's over full. This would likely explain why it's shifting so hard. But now I have some questions.
First what kind of damage can having the fluid overfull do to the transmission? Serious? second, since I have to bleed it, should I just got ahead and give it a service since I'm under there(new filter, fluid, and gaskets). Or should I pay to have it flushed? automatics are a new thing to me. I've never worked on one before 
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How far overfull is it?
I dont know a ton about automatic transmissions but I dont think having it overfull would cause it to shift hard. My guess would be that there is something going on with the valve body. Either something is sticking or something is worn out. How dirty is your trans fluid? Does it smell burnt? I honestly dont think changing the fluid will buy you much unless the existing fluid is burnt or dirty. |
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Quoted:
How far overfull is it? I dont know a ton about automatic transmissions but I dont think having it overfull would cause it to shift hard. My guess would be that there is something going on with the valve body. Either something is sticking or something is worn out. How dirty is your trans fluid? Does it smell burnt? I honestly dont think changing the fluid will buy you much unless the existing fluid is burnt or dirty. About a quarter to a half over the "full" mark. Fluid looks clean, doesn't smell burnt at all. |
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Overfilling the trans by half a quart won't cause it to shift poorly. I actually add an extra quart to the 4T65E's in GM's because sometimes when people are driving around a long curve or highway on-ramp the trans fluid will actually run to one side of the pan causing the trans to cavitate and slip for a moment or so.
My guess would be that you may have a broken accumulator spring. Those tranny's are usually good for around 150-200k depending on how they are driven. Take it to a reputable shop that does trans work and have them take a look at it. |
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Something I've had good luck with is a welded on trans drain plug. So, you can drain the trans pan, from the bottom, without leaving any fluid. Some of the aftermarket drain plugs leave a quart inside, due to poor design.
Anyway, I drain the pan and re-fill with M1 ATF nearly every oil change on my trucks. It's 4 quarts. I can't say for sure that my transmissions last longer, but it makes me happy and I've never had a failure. |
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Quoted:
Something I've had good luck with is a welded on trans drain plug. So, you can drain the trans pan, from the bottom, without leaving any fluid. Some of the aftermarket drain plugs leave a quart inside, due to poor design. Anyway, I drain the pan and re-fill with M1 ATF nearly every oil change on my trucks. It's 4 quarts. I can't say for sure that my transmissions last longer, but it makes me happy and I've never had a failure. I always hated how there was no drain plugs welded on some of these pans. I always make a mess when dropping them to swap out the filter, even when using a large drip catch pan. |
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Quoted:
Quoted:
Something I've had good luck with is a welded on trans drain plug. So, you can drain the trans pan, from the bottom, without leaving any fluid. Some of the aftermarket drain plugs leave a quart inside, due to poor design. Anyway, I drain the pan and re-fill with M1 ATF nearly every oil change on my trucks. It's 4 quarts. I can't say for sure that my transmissions last longer, but it makes me happy and I've never had a failure. I always hated how there was no drain plugs welded on some of these pans. I always make a mess when dropping them to swap out the filter, even when using a large drip catch pan. I haven't gotten a good look at it but I think they didn't put a drain plug on my pan either. 4 quarts for a truck? WTF it's 7 quarts for mine... 
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Quoted:
4 quarts for a truck? WTF it's 7 quarts for mine... 4R70W has 4 quarts in the pan. My method does not drain the converter or trans internals. Just the pan. However, if done at regular oil change intervals, the trans fluid is always fairly fresh and free of excess contamination or metallic particulates. |