Any danger if I overfill my auto tranny ?

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My 4 cyl camry has a tranny with 5.6L capacity, any danger if I overfill it? I have drained & refilled it 3 times to get most of the old fluid out. I find that it shifts smoother if I overfill it 1.0L above the 'hot max' mark.
 
In the owners manual of your Toyota it says in BOLD print: "Avoid overfilling or the transaxle could be damaged"
 
Really? My manual doesnt say anything about overfilling. So how exactly would it get damaged if it were overfilled?
 
I remember way back in '96 or '97, I had a '90 Ford Ranger pickup with the 4.0l enigine and auto tranny. I had a transmission service done and after i got home, I checked the fluid level. It looked a little high to me, but I wasn't sure, because it's so **** hard to get an accurate reading with those tranny dipsticks. You would think in this day of modern technology a better system would have come around by now...
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Anyway, I took off up a long steep mountain pass the next day in the middle of summer. The next thing I saw was a huge cloud of smoke behind me. I pulled over, popped the hood, and the tranny was puking the fluid right out the dipstick all over the exhaust manifold. Now I new the **** thing was overfilled.
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I continued to the top, and stopped and went for a hike. After I got back a few hours later, I rechecked the fluid level and it was right where it was supposed to be on the dipstick now.
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Thats about the only Ford compliment I can give after having that Ranger.....
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I assume that you mean to overfill it 1 L after the tranny has been driven for 10 miles to heat up etc. Overfill when cold or engine not running does not indicate much.

Probably not hurt anything either. I have asked several mechanics on this and other then coming out of the fill dipstick tube they do not seem to see any problem with overfilling. Personally, I do not overfill. I measure what has been drained and add that same amount back and check when tranny is hot!. Most dealers and shops refuse to take the time to drive a car 10 miles to heat it up, they let it idle etc. but it ain't the same. Always check the fluid if you had a shop do the work. In mycase they get it wron 90% of the time
 
Overfilling is not recommended and can cause poor performance or damage to seals. Like was posted, it can overheat and come out the fill tube, hit hot engine parts and start a fire. Been known to happen. In 1997+- GM redesigned the fill tube dip stick with a locking feature so the hot ATF would not blow out the dipstick and catch on fire.

It easy to reduce the level, just loosen the tranny return line to the radiator which is usually the top line. This is best a 2 man job, hold a container under the line and have someone start the car. When you think you have enough, turn it off and top off as needed. Note--It important to check the fluid level with the trans as normal operating temperature and the vehicle on a level surface.
 
quote:

Originally posted by dave89144:
I remember way back in '96 or '97, I had a '90 Ford Ranger pickup with the 4.0l enigine and auto tranny. I had a transmission service done and after i got home, I checked the fluid level. It looked a little high to me, but I wasn't sure, because it's so **** hard to get an accurate reading with those tranny dipsticks. You would think in this day of modern technology a better system would have come around by now...
dunno.gif

Anyway, I took off up a long steep mountain pass the next day in the middle of summer. The next thing I saw was a huge cloud of smoke behind me. I pulled over, popped the hood, and the tranny was puking the fluid right out the dipstick all over the exhaust manifold. Now I new the **** thing was overfilled.
shocked.gif

I continued to the top, and stopped and went for a hike. After I got back a few hours later, I rechecked the fluid level and it was right where it was supposed to be on the dipstick now.
grin.gif

Thats about the only Ford compliment I can give after having that Ranger.....
crushedcar.gif


My goodness, theose "Blue Ovals" really suck, don't they? No, they bite. I still have nightmares of my old 351 V-8 Bronco. Since this is an oil site, I must say I never had an engine-block related problem. But the electrics, the clutch, and the chassis: ohhhh, I could never make it out of the driveway! And remember the Firestone/Ford tire scandal? My Bronc ate tires like there was no tomorrow. I was lucky not to have it flip because of a tire blowout, I always caught the delaminating tires before they could kill me. Conclusion: Blue Oval: the worst darn thing on Earth!
 
i overfilled mine and drove it for 50 miles, it started to leak and i drrained it but it still is leaking now...i guess it ruptures some seals
 
quote:

Overfilling an AT can cause aeration in addition to the factors already discussed. Air is a poor substitute for lubrication as well as a poor power tranfer medium in an AT. Ergo, the effects of overfilling can be as detrimental to tranny life as underfilling. (Aeration could also be why you notice smoother shifts with an extra liter of ATF, too, since foam is being used as the power transfer medium at the clutch facings. But, the "advantage" could be short-lived if it results in premature clutch facing wear.)

Listen to Ray's wise words, Grasshoppers. The areated ATF is reducing the transmission line pressure. Overfilling will kill a transmission as surely as underfilling will.
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Overfilling an AT can cause aeration in addition to the factors already discussed. Air is a poor substitute for lubrication as well as a poor power tranfer medium in an AT. Ergo, the effects of overfilling can be as detrimental to tranny life as underfilling. (Aeration could also be why you notice smoother shifts with an extra liter of ATF, too, since foam is being used as the power transfer medium at the clutch facings. But, the "advantage" could be short-lived if it results in premature clutch facing wear.)
 
Some transmissions can burp. They usually either have a vent or leak out of the dipstick. I doubt that overfilling will pop any seals unless vent is clogged or non existent!

Also, believe the aeration issue. Never ever overfill. Since most people don't know how to check the ATF, it is important to be as accurate as possible to make up for owner inaccuracies(or incompetence)! A little either way for the normal driver shouldn't hurt the tranny.
 
KEN, well on my 4cyl camry I prob filled the tranny about 1/4qt over (using the first reading on the dip stick), it's about 1/2cm above the max mark. Haven't had any problems with 10K on this overfill.

I didn't intend to overfill, but I vacuum pumped the ATF out of the tranny and kinda estimated how much i pumped out by pouring the atf into empty quart bottles, I added a bit more since the atf I pumped out was warm.

Doesn't some of the atf overflow into the front Diff?
 
I finally siphoned off the excess fluid and now the level is exactly between the 'hot min' & 'hot max' marks. But what baffles me is that the manual states that a drain & refill is 'up to 2.5L', but it seems to fill up with only 2.1L? Dipstick error? The other thing is that the difference between the 'hot max' & 'hot min' is only like 100mL! Why on earth did the manufacturer's design it that way? +/- 50mL either way and you risk DAMAGING it??
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When you do drain and refill in a auto tranny via drain plug or removing the pan, not all the old fluid will be drained. There will still be some fluid left in the torque converter. It's probably pretty hard to determine how much fluid will remain in the torque converter after a drain, probably the reason why the manual indicates "up to 2.5L", meaning not more than 2.5L but certainly, it could be less... I find that the best way to avoid overfilling is to measure how much fluid you got out and refill *exactly* that much. I got me a funnel with measuring marks in it, and I use it to measure the drained fluid and to refill the tranny.

[ March 04, 2003, 08:46 PM: Message edited by: GimmeTorq ]
 
Can you believe there is only a 10mm difference between the 'hot max' & 'hot min' and 6mm difference between the 'cold max' & 'cold min'.
 -

This morning I checked the level when cold (engine running), it was exactly between the 'cold max' & 'cold min'!
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After 3 years of owning this car, I finally manage to get it right!
 
I have found that ATF expands ALLOT when hot so when you measure the amount you removed, make sure the amount you are putting back in is at the same temperature, otherwise you will be overfilling if you use the same amount. The amount of overfill will vary with the temperature differential of the two fluids.

Been there done that.
 
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