What can happen if the trans fluid level is too high?

[Patman]

This morning I had a trans flush done on my car, and it's possible they might have added about an extra quart of fluid to it, although the dipstick is very tricky to read (it shows different levels on either side of the stick)

How much extra fluid can the 4L60E tolerate before problems occur, and what problems would occur?

The trans seems ok to me though, in fact it seems smoother than it has ever been. I have a feeling it was down a quart before the trans flush though.

(FWIW, it was one of those full flush methods done to it, where they do not remove the pan)

[jmd]

I don't believe in those flushes because removing the pan to clean it out & doing the filter is more effective than replacing a higher % of fluid. "Full-Flush" = still a "partial flush" </ :rant: > :p

Because the 700-R4 / 4L60 use a bottom feed filter, there's no reason to overfill. Average your two level readings, or flip the stick & then average the readings on the engraved side of the stick. You probably are a bit over, but not enough to hurt anything.

[Patman]

What I do is get the normal method of the pan drop/filter swap done one year, then the flush method the next year. So my method is probably ok since the filter is never super dirty anyways. It's kind of like how some people do the pan drop/filter swap type of change every 2 years, but in my case I'm getting the flush done in the middle.

[2002ws6_mn6]

If you trans if overfull you may experience leaks.. It's not as bad as overfilling your crankcase.. There's no moving parts that will slosh your fluid around and airate your fluid like will happen to an overfull crankcase..

Those trans flush services are not worth it.. Unless you know who is doing it.. A couple of things to remember when getting a Trans Flush:

1. Chances are you will not be one of the lucky ones to get a brand new filter on the flushing machine.

2. The flusher pumps the fluid in reverse direction - pushing contaminants OUT of your filter.

Simply changing your filter will leave about 2/3 of the trans fluid in the transmission. So.. a flush is a good service to get provided you do, in this order:

1. Drop the pan and change the filter.
2. Change the filter in the trans flushing machine (not really in your control, helpful to know somebody).
3. Flush system

Now.. one last thing..
I brought my 1998 Grand Prix in to the dealer in December for a couple of problems.. one being a mushy shifting transmission. They told me I need a Trans flush.. I said no. They pretty much talked me into it and I agreed because I want it documented that I had a problem and I did the recommended service if the trans did eventually go. So after about 2 months my trans took a dump.. It's back in the dealer right now getting the trans rebuilt.. Was it the flush? Can't be 100% sure but I'll tell you what.. I'll never do it again (unless I can confirm the steps above are performed in that order).

:rant:

[SlowLX]

At the Ford dealership I work at we have a service where we drop the pan, change the filter, then flush the trans. Simply dropping the pan and swapping filters still leaves contaminated fluid in the converter and cooler (unless you are cool enough to have a Ford with a drain bolt on the converter ;) )

Regular maintenance of your trans should be effective enough, but some people come in with 100k mile fluid and expect a flush to take the place of a rebuild

[Patman]

I know a lot of people think the flushes are bad, but if the fluid is never totally dirty to begin with, I think that I won't have problems.

I bought my Firebird in Oct 2001, with 56,000 miles on it, and immediately had the fluid completely flushed in the trans, but no filter swap. The operator commented that the fluid coming out could not be original, it had probably been done within the year since it was not too dirty. Then in the spring of 2002 I went to the GM dealer and had them drop the pan, clean the magnet and put on a new filter and of course about 5qts of fresh fluid went in. And now at 98,500 miles, I get the trans flushed again. So I haven't had any problems from the first flushing, so I don't expect any from this one, since the fluid probably didn't have much dirt in it at all, I simply wanted to make sure it got refreshed for this racing season coming up.

If dropping the pan and changing the filter wasn't so damn messy, I'd simply do that myself every 6 months or so.

[2002ws6_mn6]

They sell drain plugs you can drill in and install in your trans pan.. Might be worth looking at especially if you plan on changin you fluid so often because you race..

[30thbird]

An overfilled auto will cause prolems. Why would anyone think there are no rotating parts to aerate the oil? Yes , it will cause aeration of the oil. This will lead to soft shifts- may feel good at low performance but will be a death wish under high demand(aerated oil is spongy)It may cause oilto expel from the breather . Foamed oil also holds heat- too much heat cuts the lifespan of the oil.
A flush type change is the ONLY way to clean all/ most of the oil. A pan change will only get 50% of the oil out as the rest is in the converter( yes its 50%). Proper flushing is done with the trans cycling fluid and gets most of the oil swapped out. A good flush should also include a filter change - why retain the old (full) filter?
The best job includes both.

[2002ws6_mn6]

Originally posted by 30thbird
An overfilled auto will cause prolems. Why would anyone think there are no rotating parts to aerate the oil? Yes , it will cause aeration of the oil. This will lead to soft shifts- may feel good at low performance but will be a death wish under high demand(aerated oil is spongy)It may cause oilto expel from the breather . Foamed oil also holds heat- too much heat cuts the lifespan of the oil.
A flush type change is the ONLY way to clean all/ most of the oil. A pan change will only get 50% of the oil out as the rest is in the converter( yes its 50%). Proper flushing is done with the trans cycling fluid and gets most of the oil swapped out. A good flush should also include a filter change - why retain the old (full) filter?
The best job includes both.

Well.. Of course there are rotating parts in an auto trans.. However drop the pan and there is a valve body.. No moving parts like connecting rods that dip into the oil and splash the cylinder walls... That's all I meant.. Yes, obviously if it is severely overfull you will run into problems..

I don't think "an extra quart" like Patman said in his post would lead to aeration of the oil..

Geeze man.. lighten up. :umm:

[LS1_Disciple]

When I did my wife's Toyota, I accidently overfilled the trans/differential (they're connected to each other in her car) by about 1-2 quarts. The stupid manual I had was so stinkin' vague. Haynes :frag:

Well, fortunately I check gas mileage at each fill up. I noticed an average of 4-5mpg drop that coincided with the trans service. I had kinda suspected it was overfilled anyways since I could see slow leaks developing. Well, I drained it out to where it should be and gas mileage went back to normal and the leaks stopped within 3k miles.

[Get Shorty]

I could've sworn that the 4l60 has an overflow tube on the top... In fact, I know it does. I've always heard that it'll just spit out the extra fluid thought that, and cause no problems.

[30thbird]

So ya go ahead and filler up t the overflow spiffy tube and ya ask the jones down the street if he thinks its ok. A quart over is excessive, period. Minimize the error if you want and bitch to the people in line for at the dealership for repair after the fact. You have the power and you now have the knowledge, do whta you want.

[ShiftinS6]

My 99Z28 always seemed to have a high fluid level. I know one of the main reasons is that the trans fluid expands as it heats up but I had to drain well over a quart one time and I can't see the heat having that much of an effect on the fluid level.

[Bad30th]

Yeah, drop the whole tranny out and shake it upside down. :rolleyes:

C'mon guys, the 4L60E has an overflow vent tube. If the fluid expands to overfull when it heats up the excess goes out the vent tube under the car. My vent tube is clipped to my torque arm.

As long as the tube isn't blocked or kinked there's no problem.

Bad30th

[Bad30th]

Originally posted by NJones
I could've sworn that the 4l60 has an overflow tube on the top... In fact, I know it does. I've always heard that it'll just spit out the extra fluid thought that, and cause no problems.

Thank you, didn't see this post before. This is the correct answer.

Bad30th

[Get Shorty]

Originally posted by Bad30th
Thank you, didn't see this post before. This is the correct answer.

Bad30th

I thought so, but wasn't sure. Some people will make you think your tranmission will explode if you overfill.

[Patman]

It's been a few weeks now and everything seems fine, my trans didn't die! :) I'm approaching 100k on it too and it still shifts awesome, just like new. Regular fluid changes should hopefully allow this sucker to last me 3 more years.