(edit....tried to fix the nomiclature after I realized the typo but couldn't....4R75W is what I meant)

Just like the title says, I'm trying to figure out how bad my tranny may be messed up. Wife got in the Expo today to go grocery shopping and it wouldn't back up.

I changed the oil and filter in the trans a while back and didn't have my manual with me at the time, I checked the oil by running the engine and placing the trans in all drive gears then put it back in park and checked the level.

Well as all you guys know, I checked the level wrong by looking at the HOT section of the dip stick when the trans was not up to its operating temperature. My dumbass thought Cold and Hot was reference to the climate the vehicle is operated in. :o When I checked it properly tonight, I was half way into the DO NOT ADD section!

So now about 3k miles later the Expo suddenly will not shift into reverse, nor overdrive, all other gears work, but shifting is definitely not what it should be.

So can any of you guys tell me how bad I screwed up? What usually gets damaged when this happens? And, is the trans trashed or fixable usually?


Thanks for any help you can offer.

 

Most gets spit out the overflow tube. Don't ask how i know that Your backing up, take the four bolts out of either front or back of the pan and very very lightly loosen the last one, start drainin. Put it into something you can pour into a funnel to re use tho. You'll be alright.

 

I think something gave up the ghost because I used my Pella Oil Extractor and removed about 10-12 oz of fluid from the trans through the dip stick and got the level in the trans down to about 3/4 of the way into the HOT section (while the trans was warm). And I still don't have Reverse or OD, and the 1-2-3 gears work fine while OD is off.

 

Yeah, this isn't from overfilling at all. You wouldn't believe how many transmissions I have seen that had been overfilled and the extra had obviously run out the vent. It must be a regular practice at some quickie lube places. LOL

This sounds like a transmission failure in my opinion.

Darrin

 

I have read in various parts of this forum and the web that this may be caused by a simple C-Clip failure that causes the break down, any truth to that?

 

Darrin....


You were/are correct. I had the trans rebuilt by a friend of the family who does trans work for a living. It works like brand new again now! Cost me $1000 for all parts and labor! Not bad in my opinion.

 

So......

To wrap up this thread for anyone who searches it out due to overfilling their trans, at least to a point of half way up into the Do Not Add section of the dipstick......

What typically fails when you run your 4R74W with over filled Fluid?

Answer: Nothing. You would have to seriously overfill the trans to well beyond the top of the dip stick gauge in order to cause transmission damage due to high fluid pressure. However, I would stick to EXACTLY what the owners manual says in refrence to filling and checking the trans fluid levels.