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What are the potential dangers of overfilling an automatic transmission?


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J.D.
New User

Aug 31, 2013, 11:14 AM

Post #1 of 3 (2376 views)
What are the potential dangers of overfilling an automatic transmission? Sign In

What are the potential dangers of overfilling an automatic transmission to the point where the was a fluid ron off?

Hello all,

I recently Purchased a 2005 Mercury Mariner for my daughter. I am not a big fan of automatic transmissions so I felt I should purchase the drive train warranty to be safe. In order for the vehicle to be eligible for the warranty, I had to drop an extra grand to have service performed to bring it up to their standards. Part of that service included "Servicing the transmission". I'm not sure what all this entailed, but I do know they changed the tranny fluid. When I got the vehicle home I noticed some new drips on my driveway. I then crawled under the vehicle and saw that a large portion of the undercarriage was wet with fluid. At first I thought it was the oil pan gasket leaking as they had changed that as well, and there was a fresh droplet on the oil pan. However, after taking it back to the dealer, I was told that they had determined that the mechanic had overfilled the tranny by a quart, and the leak was actually transmission fluid. They indicated they had removed the excess fluid and will be replacing the transmission fluid tube and dipstick. So now my concern is; if there was enough pressure to blow the seal on the that tube, what is the real potential that the overfilling has also compromised the integrity of the seals or caused other problems? In researching this on the web I have seen many say that there is potential for seal blow outs.

The vehicle wasn't driven too much during the period after the transmission service. I would say less than 200 miles, mostly highway.

Any insight is appreciated.

J.D.


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Aug 31, 2013, 12:09 PM

Post #2 of 3 (2370 views)
Re: What are the potential dangers of overfilling an automatic transmission? Sign In

Which engine? 2 or 4wd? Hybrid?

Overfilling the transmission with ATF can cause the ATF to become foamy. This happens because the fluid level is high enough for the rotating components in the transmission to churn the fluid with air. The air trapped in the fluid causes the pump to cavitate resulting is hydraulic and lubrication problems.

If there are no problems now, be sure to have them notate on the repair order that the transmission was overfilled by them and any damage to the transmission from overfilling is unknown at this time. That way if you have problems down the road due to the overfilling, you have proof.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Aug 31, 2013, 12:32 PM)


J.D.
New User

Sep 2, 2013, 6:16 PM

Post #3 of 3 (2334 views)
Re: What are the potential dangers of overfilling an automatic transmission? Sign In

It is the 4WD model. I also saw on a YouTube video, that if the transmission leaks more after driving as opposed to leaking when sitting, it is like to be the torque converter seal that is failing, rather than the pump cover seal. Does that sound correct?

I will certainly ask the dealer to make the notation you recommended, but I'm sure they will be opposed to doing that as it leaves them open for further liability even though they may have caused more problems that they resolved.

Thank you for responding - A appreciate the insight.

J.D.






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