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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29427
Experience:  GM Grand Master Technician 2007. 14 years experience.
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During an oil change in May the shop noticed my transmission

Customer Question

During an oil change in May the shop noticed my transmission fill car was missing. The fill cap was not replaced after repair work by the Chevy dealer back in Feb. I immediately took my back to the Chevy dealer and they replaced the cap and flushed the transmission. They assured me no damage was done to the transmission. However, 2 days ago the check engine light came on...took my vehicle to Chevy service and was told I need to replace the transmission. My question is: is this a coincidence or could driving with the cap off for 4 months have damaged the transmission?
Submitted: 12 months ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 12 months ago.

Hi there, I am Cam. Can i get your first name please?

I am sorry to hear about this issue. I will help you with it.
The answer is yes. The transmission is a closed system, by that i mean this. Unlike the engine that has fuel and air constantly going in it, the transmission does not. Only slight air movement happens with normal expansion and such. Having the cap missing could allow debris into the transmission and that debris may have exceeded the filtration capacity of the transmission. Why it only lasted 2 days past is concerning and I have another theory about that.

Here is what I am thinking. With the cap missing, I am thinking with the flush they did, they either over filled or under filled it causing this issue. Low fluid causes a loss of hydraulic pressure, but over filled causes foaming due to fluid hitting the components and aeration results in a loss of pressure. I would go back and question them on these points. I would think that you would have had some issues prior to this if it was only because of the cap missing.

Customer: replied 12 months ago.
Just to clarify, the missing cap was replaced in May along with the flushing. Was told about needing a new transmission 2 days ago 10 Dec
Customer: replied 12 months ago.
Also the vehicle has 95000 miles, is that the normal lifespan of this transmission under normal conditions
Customer: replied 12 months ago.
First name is Tony
Expert:  GM Tech (Cam) replied 12 months ago.

OK, Misunderstood. So it lasted 7 months. The normal life span is more than 200,000 miles, but all of that will depend on how its drive, loads, warm up cycles and if there are any weak components in the transmission. In your case though, the cap bing missing may have as I mentioned caused contaminants to enter the system and cause premature wear on your transmission.

To get it replaced, if you are using a GM rebuilt unit, it will come with a 100,000 mile warranty, and that in itself should say something to the life. If they warranty the rebuilt ones for 3 year, 100,000 miles, they should easily last double that.

Customer: replied 12 months ago.
The bot***** *****ne is they want me to pay $3600 to replace the transmission. I have a meeting with service management next Tuesday to discuss this. If there's the slightest chance their negligence back in Feb caused premature wear on the transmission then I want them to bear some of the replacement cost. Thoughts???
Expert:  GM Tech (Cam) replied 12 months ago.

Sorry for the delay. I am on the ambulance today.

I believe that there is a better than even chance the failure was brought on by the cap being left off and that they should pay for it. However I expect that they will either completely deny any wrongdoing and push the entire cost to you, or pay a portion. I will say that I would be shocked if they pay all, rather I suspect they will work out a deal, maybe you pay parts and they take care of labour, or they cover a percentage of the repair. I hope they do, but again, that will be up to them. Please let me know what they decide.