Too Much Trans Fluid

[dab18351@epix.net]

Can to much trans fluid in a 2001 blazer effect how it performs?(shifting,passing gear, overdrive......)

[Jay2TheRescue]

Overfilling a GM automatic will cause frothing & foaming in the fluid, then it won't lubricate & protect the tranny like it should, and can lead to tranny overheating and failure. If you're overfilled, even by just a little get it out! I once accidentally overfilled my Buick's tranny by about 1/4 - 1/2 quart. I drove less than 50 miles before it would not shift. I took a whole roll of paper towels out of the trunk, wiped the dipstick, then put it back in, wiped it again... till I removed the excess fluid. Then I had to drive 20 miles home stuck in 1st gear. Was not a fun day.

-Jay

[kamesama980]

absolutely it will. overfilling is a quick trip to the tranny junkyard. make sure you read in the manual how to check it (usually a 3-4 step process)

[mikemoss]

I was told by a tranny builder on ls1tech.com that he likes to fill the tranny to the fill line and then just a hair above but a quart to much could be too full.

[Jay2TheRescue]

With any automotive fluid I'd rather be a pint low, than slightly above the mark. Bad things can happen if fluids are overfilled.

-Jay

[RoadWarrior]

Originally Posted by mikemoss

I was told by a tranny builder on ls1tech.com that he likes to fill the tranny to the fill line and then just a hair above but a quart to much could be too full.

Yeah there's some trannies that are better off a touch overfull, it depends where the level comes in the pan. If it stays below moving parts it won't foam or anything and guards against sucking air on hard braking and cornering.

I had a Jimmy that behaved a lot better when it was about 1/8" over the full line.

It can vary a lot by car though, typical tranny dipsticks have rubber seals that can compress some, and the plug is often crimped on the stick and can move up it with repeated firm insertions, so what might be good on one vehicle might not be good on another.

[mikemoss]

^^ Good point but if his blazer is a v6, I know it doesnt say v6, and an auto then it has the same tranny as my camaro and basically every other rear wheel drive front engine automatic has had since the early 90s the 4l60e which is just an electronic 700r4.

That is why I said the thing about what that tranny builder told me bc it was about the same transmission.

And about the moving parts. Does the valve body count as moving parts if not then the pan sits way below the insides of the transmission on that tranny, I have had the pan off and have had the valve body off of a 4l60e.

[RoadWarrior]

Maybe I should have said rotating parts. Bathing the bottom of the valve body should be okay, but you don't wanna submerge it too deep or it's bleeds and vents will be working against the pressure due to depth. Remembering also to leave expansion room for when it's as hot as it can get. Oh another return to avoid sinking too deep would be the cooler return.

I think it was the 4L60 non E in the Jimmy, it was an '88 with the 2.8 V6.

Marvin's tranny, the A670, a torqueflite based A413 FWD transaxle with the V6 bellhousing, would also be okay overfull by some, as far as I can recall, that would be up to about an inch from the very top of the stick. But that might tend to bathe the output shaft under hard acceleration so probably staying just a quarter to half inch over full is safer.

Let's remember though, that although a touch more fluid seems to give a bit better clamping and quicker shifting on some trannies, which should improve FE, lots more, even if the pan will take it, will tend towards hurting FE, just because it's that much more fluid which has to absorb heat before it's up to proper operating temperature. Severe service applications might regard this as a plus though.

[theholycow]

Originally Posted by RoadWarrior

just because it's that much more fluid which has to absorb heat before it's up to proper operating temperature. Severe service applications might regard this as a plus though.

What is proper operating temperature, anyway? Now that I have my SG I have been monitoring my ATF temp and it takes 20 miles or more to get up to its stable temperature (possibly because of the extra-large cooler I've got for towing).

[Jay2TheRescue]

I've got the HD towing package too, and mine hovers around 140 - 150 when warm.

-Jay

[theholycow]

How much driving does it take before it reaches the 140-150 range?

[Jay2TheRescue]

It never gets there in short trip city driving, but at speeds over 45 MPH it takes about 20 minutes. It doesn't seem to get much higher than that, even when on the highway for an hour or 2. I think the highest I've ever seen the TFT is 160 or 170, and it didn't stay there for long.

-Jay