Transmission Fluid

[Dwight]

I recently wanted to check the fluid level of my Sierra 5 speed, and after considerable effort with a modified hex wrench I was able to open the fill plug.  My understanding was that the proper level should be such that it comes up to the opening of the fill hole.  However, upon removing the plug, a substantial amount of fluid came out.  Does this mean the trans was overfilled?  
 

Can someone with some experience in this regard please provide some guidance.

 

Thanks so much.

 

Dwight

[NSXguy]

Really depends how level the car/trans was when filled or when you opened the fill plug. but generally on most trans fill until it starts to come out of the fill hole. 

[JohnCh]

If the car was level when you checked, then either someone filled it when it wasn't level, or they filled it with the top cover off.  Or you could be lucky and a previous owner added a filler plug on that top cover.  Regardless, you don't want to overfill the gearbox.  In fact, Ford reduced the amount of oil required during the type-9 run by lowering the fill hole location.  Might be worth going through some of the downloads in the Gearbox section here.

 

-John

 

 

[Croc]

 

Sounds like you found the right level now.  Running too much oil usually just increases oil and transmission temps.  So you may have got away with things with no harm done.  

[Dwight]

Thanks so much for your knowledgeable responses.  I’ve decided to just reinstall the plug with the oil at the level of the plug opening.  I’ve got to tell you, however, it was a “bear” getting the plug back in with the very limited clearance.  It required further extensive grinding of a 10mm hex key to facilitate the process, but it’s done.  Thanks again.

[Edger]

Bountiful knowledge here. Good to hear you've done it right.