Aod engaging weird

[91merc]

On my 91 GM since I got it running again it hesitates when putting it in gear, the fluid is a little on the brown side and when I put a new radiator in it, it got started and puked some out of the lines, could it be as simple as driving it a bit to burp the air out? The most I’ve driven it since I did all the work is putting it on a trailer to go to the exhaust shop, I also replaced the bushing on the throttle side of the TV cable

[gadget73]

sounds more like low fluid level honestly. The cooler will burp itself almost immediately from flow but you will need to top up whatever was lost from the radiator swap.

[friskyfrankie]

sounds more like low fluid level honestly. The cooler will burp itself almost immediately from flow but you will need to top up whatever was lost from the radiator swap.

+1 on both counts. Was that much trany fluid lost just from the cooler? I would still check the condition and level of the fluid at the proper time and on level ground. As stated, it could be as simple as that.

[gadget73]

Just changing the radiator I'd guess maybe a half quart, but transmissions are prone to leaking anyway so it might have been low to start with. More than about a quart or so and I've found the AOD is slow about engagement.

[91merc]

Is there any chance the valve body drained out from sitting over a year and I just need to drive it a bit to get the air out?

[friskyfrankie]

If the level is correct and not disintegrated, I'd drive it to see how it operates over time.

[sly]

One run through the gears should have removed all air unless there's a valve body gasket issue causing leaks. That said, the stock tune is very soft shifting anyhow, so if it takes more than one second to engage, you may have internal leaks or low fluid level. AODs are also known for an issue called morning sickness where the pump internal seals will leak out and fail to engage until enough heat is created to have the seals and/or pump case expand those few thousandths to fill in the gap and start pumping correctly.

[91merc]

One run through the gears should have removed all air unless there's a valve body gasket issue causing leaks. That said, the stock tune is very soft shifting anyhow, so if it takes more than one second to engage, you may have internal leaks or low fluid level. AODs are also known for an issue called morning sickness where the pump internal seals will leak out and fail to engage until enough heat is created to have the seals and/or pump case expand those few thousandths to fill in the gap and start pumping correctly.

Since I’ve got it running again I haven’t driven it anymore than just pulling it on a trailer to go get tagged and title transferred, it’s just been hesitating when you initially put it into gear

[sly]

If the initial hesitation is more than 2 seconds, there may be an issue. If it's less than 2 seconds... it's probably fine. If it has a shift kit installed, this should probably be less than 1 second.

[91merc]

Update:

I got it up to temp and topped it off and the hesitation is gone, and it goes through all the gears really good except the 1-2 up shift is a bit slow, I’ll probably drive it a little tomorrow and recheck the fluid

[friskyfrankie]

Sounds good! Just keep an eye on the level and condition of the fluid and you may be fine!

[91merc]

Sounds good! Just keep an eye on the level and condition of the fluid and you may be fine!

im hoping that’s all it is, it seems like it has to search for 2nd for a bit when shifting up from 1st and I’m hoping it’s just a matter of running it through the gears and needing to top off fluid again. Other than that it shifts smoothly between the rest of the gears

[sly]

That should be all it is. The upshift being slow may be an indicator of a plunger in the valve body sticking a bit. Driving more may help that, but if it doesn't, as long as it doesn't get worse, it should be fine.