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What happens if you overfill your trans?

19K views 10 replies 6 participants last post by  JJ350 
#1 ·
I posted a question the other day as to why my truck takes off when I put it into gear. I haven't had time yet to look into it, but I did check the oil this morning and noticed it looked like chocolate milk. I just changed the oil last weekend. Any way this brings me to think I overfilled the trans when I changed the trans a few months ago forgetting to drain the fluid it already had in it before putting fresh fluid in. I'm assuming the engine is sucking trans fluid threw the line that goes to the modulator down the intake?? So just curious as to what actually happens when a person over fills a trans.. thanks.
 
#2 ·
What happens if you overfill

While chocolate milk is tasty and good to drink, fluid that looks like chocolate milk is not good. [ to drink or for your trans ].

First, how much over full is it [ do you not have a dipstick? ]

Second, what type of trans is it, some transmissions are very sensitive to too much fluid. Such as the thm400.

A little over may not be a problem, but too much will cause all sorts of problems, on some units.

Have you pulled your vacuum line off, at the trans, to see if fluid would run out [ it should not ]
 
#5 ·
what happens

The act of overfilling your trans would not cause the modulator to go bad.

Check the hose, check your fluid level.

If it is overfull, and the fluid looks nasty, but the trans works good, drain out as much as you can.

Take a good look in the pan, hopefuly you won't see much debris.

If that is the case, well just getting the nasty fluid out will go a long way to insuring that the trans will stay working good. Good luck!
 
#6 ·
JJ350 said:
I posted a question the other day as to why my truck takes off when I put it into gear. I haven't had time yet to look into it, but I did check the oil this morning and noticed it looked like chocolate milk. I just changed the oil last weekend. Any way this brings me to think I overfilled the trans when I changed the trans a few months ago forgetting to drain the fluid it already had in it before putting fresh fluid in. I'm assuming the engine is sucking trans fluid threw the line that goes to the modulator down the intake?? So just curious as to what actually happens when a person over fills a trans.. thanks.
I dont know the answer to that ?, but what I like to do on a good tranny service is to rig a 2.5 gal gas can full of atf under and connected to pickup with hose(with pan removed) and suck the can dry.
This can make a big mess so put the gas contaner inside a larger(kitty litter) plastic tub.....
This will flush clean atf thruout trans/convertor....
Drilling and tapping a drain hole"aka MB" in convertor also a idea...
:)
 
#7 ·
A faulty modulator will allow oil to get sucked through it, a good one will not.
I always heard that when you overfill a trans or motor the rotating parts whip air into the fluid that is in the pan. The idea is that the proper fluid level should be a fair distance below these rotating parts. When you overfill it, the level is so high that it touches those rotating parts.
Air does not lubricate, so the little bit of oil that is present in that frothy fluid gets overworked , burnt and starts to allow metal to metal contact. :pain:

Also, oil expands when it gets hot, and overfilling can lead to pushing the excess out the vent.


I can't say that I know all that is the absolute truth, , it's just what my pappy tol' me. :thumbup:

Later, mikey
 
#8 ·
the oil this morning and noticed it looked like chocolate milk.

Does it smell burnt?

It ought to Ive seen the "strawberry milk shake" water & trans mixed but chocolate milk

YUK

sounds like you need to find a shop that can do a blood transfusion the have a machine that does this I think its a motor vac brand.

Have them pull the pan & look for ground up metal parts.

Most likely your trans is living on borrowed time :pain:




R :thumbup:
 
#9 ·
Just to elaborate the chocolate milk look I was referring to ins't the trans fluid, it was the engine oil, thats why I was thinking the modulator is faulty and is allowing the fluid to get sucked into the intake and down into the cylinders. Thanks to everyones responses, I still havent' had the time to remove the vac. line to see if trans. fluid is coming out.. i've been very busy...
 
#10 ·
JJ350 said:
Just to elaborate the chocolate milk look I was referring to ins't the trans fluid, it was the engine oil,
Engine oil that has the appearance of "Chocolate milk" is usually the result of water in the oil.

Some possible causes are:

Intake manifold gasket installed incorrectly.
Blown head gasket.
Cracked head.
Cracked block.

If the modulator valve was broken internally and allowing trans fluid to be sucked back to the intake manifold at the vacuum connection, this oil would go out the exhaust and would /should cause excessive exhaust smoke. It would not enter the engine oil to mix with it.
 
#11 ·
How about the tarp that I have covering my truck has a hole in it :D There was standing water from the rain on my intake, and it was all the way up past the dizzy gasket.... I have a hole in my hood to run a scoop that I don't have yet... I tape some plastic over it , hopefully that will do it.. thanks everybody.
 
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