Alison Trans issue

[jason.erbecker]

My starboard transmission lever stopped being capable of its full range of motion the other day. It travels fully to the reverse position, but not to the full forward position. It is a hard stop approx 3/4 of the way to what would be the fully forward position. While it will, in fact, go into gear, there is a delay in doing so. Is this a common gripe? Thoughts?

 

[Pascal]

First pop the cover on the control and check for something loose. Check the linkage on the gear as well. It could be loose and about to disconnect.

Try engaging the gear manually.

As to the delay, low fluid level and/or low gear pressure cause a delay engaging in forward but not in reverse. Do you have a delay in reverse ? Check oil level (With the gear warm and engine idling). There could also be an air leak at the screen on the gear. From memory it s triangular with 3 bolts and the gasket is not the best.

Now all these is from memory as I haven’t used an Allison gear in years

 

[jason.erbecker]

I couldn't see anything loose under the cover on the controls. The delay is only going into forward, reverse works as expected. It looks like I'm good to go with oil level. I'll check the linkage and the screen. Thanks for pointing me in the right direction.

 

[KPTIM]

Hi Jason,
Someone you know in Hampton at your marina is going to reach out to you with a suggestion.
Hope it helps

 

[Pascal]

Why does the pressure gauge show compared to the other engine?

Delay forward is always low pressure.

Undo the cable at the gear and check if the Cable pushes it all the way. Then try engaging it by hand

 

[jason.erbecker]

Hi Jason,
Someone you know in Hampton at your marina is going to reach out to you with a suggestion.
Hope it helps

Thanks, Tim. I certainly appreciate it.

Jason

 

[jason.erbecker]

I will be down at the boat tomorrow and look at what the pressures are reading, etc. Hopefully something simple as I am just learning this beast! More to follow...

 

[SEVEN]

You probably already know this but I’m just double checking. Make sure that you’re checking the transmission fluid levels while the motor is running. A friend of mine looked at his levels while not running and it showed full. Once he started he only had reverse and no forward. It turned out he was almost a gallon short of fluid while the motor was running.

 

[Pascal]

What I did on mines is bring them to the correct level warm and idling then mark the dipsticks the next morning when cold. Much easier and never had an issue after that

 

[SEVEN]

Great point Pascal.

 

[jason.erbecker]

You probably already know this but I’m just double checking. Make sure that you’re checking the transmission fluid levels while the motor is running. A friend of mine looked at his levels while not running and it showed full. Once he started he only had reverse and no forward. It turned out he was almost a gallon short of fluid while the motor was running.

SEVEN, thanks. I did not, in fact, know that little bit of info. I appreciate it. I'll dive into this in an hour or two and see what I can see. Thanks again.

 

[SEVEN]

Let us know what you find. Let it run for a few minutes before checking.

 

[Nonchalant1]

It's been a long time since I did this, but it sounds exactly like you need to clean the screen and fix an air leak at that junction. It's on the suction side before the pump, so air gets in and stays in the fluid. I had that same issue and it was a simple fix. Get a new gasket. Then remove the 3 bolt flange and clean the screen and reassemble. Maybe others will remember, but I believe once that it is back together then just running it will get the all remaining air (from working on it) out of the system because the pump will now be drawing air-free fluid from the trans and pushing clean fluid throughout the system.
Doug

 

[ageless]

You probably already know this but I’m just double checking. Make sure that you’re checking the transmission fluid levels while the motor is running. A friend of mine looked at his levels while not running and it showed full. Once he started he only had reverse and no forward. It turned out he was almost a gallon short of fluid while the motor was running.

Does this apply to all gears or just the Allison? I have ZF and have not heard this

 

[jason.erbecker]

Hatterati, Thanks for the advice on this. While the engines were shut off I put both transmissions into forward gear. I then went down to the engine room and visually compared the two. The port trans, which was working perfectly well, had the shift lever the cable connects to noticeably higher than the starboard. I disconnected the starboard shift cable from the lever and saw that the range of motion shifting manually was much further. I adjusted the cable length, reattached, and am back to being a happy boater. Gear oil pressure is 150psi for both. Level looks right. She shifts into/out of forward & reverse without the long delay. I think I’m good to go. Thanks for all the help, I appreciate it.

 

[Pascal]

Glad it was just the cable...

 

[SKYCHENEY]

Does this apply to all gears or just the Allison? I have ZF and have not heard this

Yes, most gears should be checked running, warm, and in neutral for proper oil levels. Check your manual for your specific gear, but that is what I have seen.