Trans overfill question

[oilpan49]

Last winter I wrecked my truck and I got stuck in the snow. I was trying to get myself out of the way of oncoming traffic because I hit a concrete barrier off to the side of the road. During all this I fried the transmission and had to have it rebuilt.

when I got the truck back I noted the transmission was overfull by 1qt. Up until the other day it wasn't a problem and now it started leaking. I thought maybe it was something simple like loose bolts and sure enough, they were loose. I tightened them back up and went for a drive. Come back and just watch the trans pan for 10 or 15 mins. No more leaks! My question is if a transmission is overfull by a qt, will it cause the bolts to come loose because of excess pressure or something else?? Thanks,,,,AR

 

[kenw]

it could cause foaming and air bubbles, and therefore possibly some lousy shifting, but more pressure? not that I can fathom.

 

[RF Overlord]

quote:

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Originally posted by Airborne Ranger:
My question is if a transmission is overfull by a qt, will it cause the bolts to come loose because of excess pressure or something else??

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Ranger, I'm with kenw on this one...I have to believe that the rebuilder left the bolts loose...being over by only 1 qt should not be of any real concern. If you grossly overheated it, it might have spewed a little out the vent, but that would be it...

 

[Ray H]

Overfilling an automatic transmission by any amount is very bad news. The overfill results in fluid churning into a froth. Froth neither lubricates well nor transmits power well. That minor, annoying gasket-pan leak was the least of your worries.

 

[oilpan49]

quote:

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Originally posted by Ray H:
Overfilling an automatic transmission by any amount is very bad news. The overfill results in fluid churning into a froth. Froth neither lubricates well nor transmits power well. That minor, annoying gasket-pan leak was the least of your worries.

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I sometimes feel the transmission when it's shifting from 1-2 around town, it delays for a split second the shifts rather hard into 2nd,,,AR

 

[JTK]

quote:

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Originally posted by Ray H:
Overfilling an automatic transmission by any amount is very bad news....

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It depends on the unit. The ford taurus/windstar AX4S/AX4N transaxles actually benefit from being *slightly* overfilled. Better shift quality.

G/luck
Joel

 

[FazerZ]

An overfilled automatic will not cause the pan bolts to loosen. Time will cause the bolts to loosen. Some cork gaskets tend to give and need re-torquing after a period of time. Sounds like a QC problem.

I agree with JTK. It depends entirely on the transmission/transaxle. Some units, ESPECIALLY the FWD Fords that use the AX4S/N (taurus, sable, windstar, etc), benefit from the extra fill and will work better. It's not fiction. Ford has bulletins that state such protocol and recommendations.

You will be surprised how much fluid it takes to make most transmissions/transaxles look overfilled on the dipstick. It's not much. It's not linear in any way. So, you cannot determine how overfilled a unit is by the dipstick (w/o some sort of calibration -- marking, experience, etc).

It's really a matter of percentage of volume and design. Large units with multiple pans and temp controlled baffles are very forgiving and likely are in need of extra fluid. Mostly FWD designs.

Large RWD units tend to a little bit more sensitive, but the real trouble-makers are small pan=less transaxles with low volume fills. 1 qt too much here could likely cause fluid to be blown out and therefore now adjusted for level! It's best to avoid this scenario.

It's best to keep fluid level @ the top of mark when in the operating temp range or just ask a knowledgeable, trusted mechanic if there is any specific recommendations about your vehicle. Most exceptions are well known.

Low fluid levels are much more dangerous and more common.

DH

 

[99]

quote:

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Originally posted by Ray H:
Overfilling an automatic transmission by any amount is very bad news. The overfill results in fluid churning into a froth. Froth neither lubricates well nor transmits power well. That minor, annoying gasket-pan leak was the least of your worries.

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Ditto. Get it out before you ruin your trans.

 

[unDummy]

Loose bolts were caused by not torquing correctly---shoddy workmanship. Overfilled transmission caused by same lame technician.

Overfilling can cause underhood fires when the ATF burps out of the dipstick.

I haven't seen the "frothy" situation yet but there were a couple of threads here concerning poor shift quality when overfilled, but I haven't experienced it myself.

Make sure you check your ATF correctly per the owners manual. Most vehicles require warm or hot ATF with vehicle running and parked on level surface. And, ATF dipsticks are more sensitive then oil dipsticks. Unless you actually removed a quart of ATF to bring level back to normal, I'm guessing that you are only overfilled by a pint or so.