checking trans. fluid

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Old 12-24-08, 04:24 PM
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checking trans. fluid

I have a 2007 Honda Accord that i check its fluid level after several hours so that the tran.fluid has a chance to flow back into the trans.,and its more convenient have a cold state reference.

Sometimes the fluid is within the full/add mark then other times its below the add mark.
I have never seen this in my American made cars.

The manual says to warm up the engine/trans. THEN check the fluid level.

I know its a somewhat silly question,but for the life of me i can't explain the level changing from day to day. The manual is of no help.

Thanks for any help.
 
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Old 12-25-08, 07:23 AM
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Wink

See if this makes sense to you...

Transmission dip sticks are a bit different than oil dipsticks, in that, they measure in pints not quarts. Therefore any change in the amount of fluid in the pan can show more of a change in the level. A half inch on a oil dipstick may indicate a change of a quart of fluid, whereas the same half of an inch on a tranny dip stick is only a pint.

All of the vehicles I have owned or checked the tranny fluid on state, "check while hot". I don't believe the engine has to be hot, but rather the tranny has to be fully engaged. What I mean by this, is that you have to shift from Park, reverse and forward several times. This ensures that the torque converter is filled with fluid, or at least as much as it can be. Once you have done this shifting sequence several times than you can check the fluid level and get an accurate reading.

If you let the vehicle set and check the tranny while it is cold, the torque converter fluid drains back and you don't get a good reading. One would assume, the same amount of fluid would drain out of the torque converter (and valve body) each time, but it doesn't. That is why your readings change from day to day. One day three pints will drain out and the next only two or something like that.

Hope this helps....
 
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Old 12-25-08, 09:19 AM
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Thanks for your reply.

Your explanation does make sense. My manual says warm tranny,shift gears also,but i was thinking that in a cool state
after several hours off the level would return to its highest level on the dipstick.

My thinking was comparing the engine oil check where the oil level does return to its highest level,unless its burning oil.

Are you saying that when measuring the tranny fluid cold it is a bogus reading?
 
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Old 12-25-08, 10:07 AM
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The procedure for checking transmission fluid is completely different from checking engine oil or any other fluid in the vehicle.

For every automatic transmission I know the fluid must be checked with the fluid warmed up, engine still running, level surface, and after shifting through all positions of the shifter, pausing momentarily at each position. The fluid isn't fully hot until it's been driven ten miles or so. Deviation from this practise will result in a bogus reading.

The only transmissions that have a different - and more involved - method of checking are certain German vehicles (VW, Mercedes - I'm sure there are others). For those, checking has to be done at a certain intermediate (not full hot) temperature. Plus, their dipstick method is different. Specific instructions must be followed for these vehicles.

Yes, a cold reading is bogus. The fluid expands as it warms up.
 
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Old 12-25-08, 10:53 AM
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Thanks

It has to be my technique.
My American vehicles when i check the trannies cold have always been at a certain point on the dipstick,however,not with this Honda. It reads normal sometimes,then other times it reads low.
I'll fully warm up the car before i check the level shifting thru the shift points.
 
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Old 12-26-08, 02:24 PM
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well, please, check what your manual says about the gear shifter position. it has to be either in parking, or in neutral, and it varies from a manufacturer to manufacturer. most have that in parking, but i remember mitsubishi having it in neutral. that may radically change the reading on a dipstick.
 
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Old 12-26-08, 05:36 PM
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I'm going to take a number of readings, according to what the manual procedure states, for several days and see if the level stays consistent at some point on the dipstick.
 
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Old 12-29-08, 10:02 AM
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Update,

I took several readings over the last couple days with the trans. warm/hot,shifted through the gears, and it was repeatable. Level was between the hash marks.

Special thanks to trying2help and Kestas.
 
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