My daughter lives in the city and has had difficulty finding parking space in this winter of big snowbanks, so she may have damaged the some line to the transmission by going over icy chunks at the side of the road. One day she took the car out and noticed it wasn't shifting appropriately so she drove right back and parked it. When I arrived to help her, there was a large puddle under the car which turned out to be transmission fluid. We had it towed and they fixed the broken line and put in fluid. Yesterday, (two weeks after the repair), she complained that the car didn't seem to downshift when going up all the steep hills to her house from the grocery store. I asked if she had let it warm up enough before driving and she admitted she hadn't. Am I on to something (young people who are impatient?) or could the transmission be damaged and she's only now seeing it? Thanks for any advice.

For most cars there is a specific routine you need to follow to properly check the transmission fluid level.

Check your owners manual.

For example - to check the transmission level in an allison tranny in a fire truck you have to drive for 10 minutes, set the idle to 1000 RPM and put the transmission in every gear, including reverse, then check the fluid level in neutral.

Most people do not want to spend the time to do it properly.

As was mentioned, you need to warm the transmission up, and putting it in every gear won't hurt.

If you cannot find the instructions, you might try a dealer, or ask this specific question of the board - How do I properly check the transmission fluid for a 2010 C30?

For most of my cars I look at the fluid level when the car is cold. If it looks the same each time, I figure things are OK.

Oh, by the way - some later model cars do not have a transmission dipstick - you cannot conveniently check transmission fluid level! DOH!

Thank you for all that detail! I actually ran into the mechanic who replaced the coolant line(or whatever it is) and he suggested we could top off the fluid to see if that would help. Your description about how to check the fluid in a fire truck is amazing! We will check the manual to see if it's even possible to know the level, or we'll bring it back to the mechanic (less convenient) and make sure it's right.

First, you need to determine the amount of ATF in the tranny. Low fluid will cause the pump to cavitate and the pressure to initiate a down shift will not be there. Also realize that cold fluid volume is much less than hot. Perhaps the shop didn't check the ATF level after warming it up?

I am surprised that one of the two lines could be damaged by road debris. Both lines should be covered by the splash guard under the engine.

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Keeping it running is better than buying new

Thank you, Klaus, for your valued opinion. The mechanic said that the shield under the car that's supposed to protect the lines going to the transmission is made of plastic and rather flimsy. I forgot to ask if he saw any evidence of of breakage on that shield. I will bring the car back for a level check and top-up if necessary. Hoping the transmission hasn't been damaged, and if his theory isn't correct (about snowbanks) I don't know what else would cause all the fluid to leak out? And you're probably right - maybe they didn't warm up the car before completing the addition of new fluid. I'll make sure they do that when I go by. Your advice is always right on and I really appreciate having a little more knowledge about the whole thing before I go back. Thanks again!

For transmissions that don't have a dip stick, a lift is required. The ATF temperature must be close to 50C, if I remember correctly, the car level, and ATF added until it starts to drain out of the hole.

I sure miss a conventional dip stick! A lot of the new cars are like this.

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Keeping it running is better than buying new