Allison Overfill Question.

[Hypocycloid3]

Did not see a spot specific for transmissions, so hopefully okay to post a question here. Regrettably, I needed to save some time before a trip and took my 05 LLY / Allison 1000 to a shop for fluid service. They over filled the tranny. I figured my bad reading on the way out was due to the incline in a parking lot and maybe the dipstick pipe also being the recent fill point. Should have been more sure (actually, should have done it myself) but anyway, towed several hundred miles on it and it came back dripping fast from the inspection hole on the bell housing at idle. I suspect the pump seal or o rings in the front got stressed from extra oil, or pressure ect. The shop owner's argument is that there wont be any pressure in there even if over filled a quart or two since the oil just sits in a huge pan, gets sucked up as needed, and my truck is only leaking now because it has a lot of miles and the timing is just coincidence.

So question is, is there any truth to what he is claiming? It takes like 7 quarts to refill and considerably more from empty... is even as much as 2 quarts not much relative to it's size and certainly not enough to do damage to seals?

 

[2004LB7]

How much higher on the dip stick is it?

The Allison doesn't like to be run over filled. It commonly results in the transmission running hot.

And there is a transmission sub section. A mod will likely move it there

 

[Chevy1925]

I’m not confident overfill was your issue but an overfilled trans will cause overworking of the fluid due to windage from the spinning hard parts. It will pick fluid up or never left fluid fully drain off the hard parts.

That said, even with some cavitation it will cause. I’d expect internal parts to cause issues before the front pump seals go from an overfill condition.

If this was an engine, it would be a different story