Where to look for automatic transmission air leaks?

Tiny
WYRICKKEN
  • MEMBER
  • 2005 CHEVROLET COBALT
  • 63,000 MILES
I see that if the transmission filter seal leaks, it can cause the transmission to ingest air causing low transmission hydraulic pressure.

This seems to fit the symptoms of my transmission exactly. The mechanic tested the 1-2 shift solenoid and put it all back together and it worked perfectly, then slowly over the course of 20 miles city driving, it got worse and worse, slipping more and more.

It seems that there is a leak somewhere and I'm losing pressure. Where/how should I look first?
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Sunday, May 6th, 2012 AT 3:21 AM

9 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Where do you see a leak? That won't cause a leak unless it gets too low on fluid.
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Sunday, May 6th, 2012 AT 3:34 AM
Tiny
WYRICKKEN
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I don't actually see a leak, but read that if it ingests air that will cause it to lose pressure. Since it shifted just fine after the mechanic tested it and put it back together, then slowly started slipping more and more as it was driven, I thought this could be the cause.
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Sunday, May 6th, 2012 AT 4:00 AM
Tiny
ASEMASTER6371
  • EXPERT
Sorry, wont be the issue here. He had the side plate off for the solenoid, not the pan where the filter is located. You need someone to do a pressure test to verify your concern. There are taps over the trans that can be used for the testing. It sounds more like there is an internal issue here.

Roy
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Sunday, May 6th, 2012 AT 4:27 AM
Tiny
WYRICKKEN
  • MEMBER
I would agree except that the transmission worked perfectly as I drove it away from the shop and only started shifting irregularly after a period of driving. Something (heat, air, leakage?) Is causing it to fail after a period of driving. I see also that the valve body gasket could be a source of leaking. Would a leaking valve body gasket cause these symptoms?
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Sunday, May 6th, 2012 AT 4:42 AM
Tiny
ASEMASTER6371
  • EXPERT
Nope, sorry, you are barking up the wrong tree. I doubt it is an air issue at all. It may be valve body as he messed with that. I still feel you have seal or clutch issue with the trans

Roy
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Sunday, May 6th, 2012 AT 4:48 AM
Tiny
WYRICKKEN
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Okay, so not air. Drove the car again this morning and same thing happened. Changed gears flawlessly for about 10 minutes and then started not finding second as easily. After about 20 minutes, second would only kick in at very high RPM and roughly. I haven't really tested 2-3. Solenoid? If it was bad I wouldn't think that it would work cold and not hot.
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Sunday, May 6th, 2012 AT 10:37 AM
Tiny
ASEMASTER6371
  • EXPERT
2-3 solenoid for 1-2 shift? I know you are grabbing at straws here but why dont you get a real diag from a trans shop?

Roy
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Sunday, May 6th, 2012 AT 11:14 AM
Tiny
WYRICKKEN
  • MEMBER
I did not write the last clearly. I haven't tested the 2-3 shift solenoid. Could it be a solenoid problem? If the 1-2 shift solenoid was bad, I wouldn't think that it work well cold and not hot, but I'm not a mechanic. I mentioned that it just came out of the shop, although not a transmission specific shop. It is doing this after the mechanic looked at it, so I'm looking for diagnosis assistance or at least second opinion. I think the mechanic's next step will be to replace the 1-2 shift solenoid. I'm not in the U.S. And will have to order all parts which will take time, so I'd like to get the diagnosis right the first time if possible. So far none of the experts here have provided any useful diagnosis assistance except to tell me that I'm not right. How about what is right (I don't have access to a transmission shop)? Maybe some steps to take in diagnosing?
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Sunday, May 6th, 2012 AT 12:52 PM
Tiny
ASEMASTER6371
  • EXPERT
First of all, we rely on the info you give us and our expierence.

Second, we are not there to diag it for you. We take the info you give us and try to come up with ideas.

Third, you are not a tech, at I assume that, and the fact that we have not told you what you want to hear is an issue.

Sorry I have not solved your issue but all we can do is lead in the right direction. Maybe someone else can guess better for you.

Roy
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Sunday, May 6th, 2012 AT 12:57 PM

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