Trim Pump Bench Bleeding?

This is a 99 vintage Alpha 1, Gen 2 drive... I somehow got water in my trim system so now I've resealed the trim cylinders, blew out the hoses, removed the trim motor/pump assy to remove and clean out the reservoir, screens and pump assy. I've reassembled the motor/pump/reservoir and filled with 10W-30 in hopes of bench checking it before reinstalling it in the boat.

The motor sounds normal but I'm not getting any real flow from the up or down fittings/ports. Each port spits pretty good like it's trying to move fluid but I'm thinking that it should fire out a pretty strong and steady stream which it definitely is not. It's sort of like it's sucking in air but it's such a basic system from the pickup screens to output ports that I can't see how this could be the cause.

Thoughts and advice are appreciated while I still have some hair left.

do you have the reservoir installed? and filled?

the oildyne 108 is a very very simple pump.

however if water sat in the pump for a long period of time, the check valves could have rusted. the pump can be pulled apart and rebuilt if needed. I see that the cost has skyrocketed in the last 15 months

Thanks Scott, that's good advice. The reservoir is filled to the max and a bit more. I did have the pump apart and the check balls looked good with no obvious corrosion.

I discovered that if I plug the opposite port to the the one that should be pumping that it then picks up fluid almost immediately and has what I would call proper flow. The same good flow happens if I reverse ports and motor direction.

Now I'm wondering if my "issue" is normal for an open pump circuit because in a closed system there would be return fluid coming back to the pump through the port I'm blocking off. OR...maybe there is an issue with the shuttle valves?? The manual doesn't mention how to service them but I'm really tempted to take them out to make sure they aren't stuck open.

Any other thoughts are appreciated. Thanks

lintmann said:

Thanks Scott, that's good advice. The reservoir is filled to the max and a bit more. I did have the pump apart and the check balls looked good with no obvious corrosion.

I discovered that if I plug the opposite port to the the one that should be pumping that it then picks up fluid almost immediately and has what I would call proper flow. The same good flow happens if I reverse ports and motor direction.

Now I'm wondering if my "issue" is normal for an open pump circuit because in a closed system there would be return fluid coming back to the pump through the port I'm blocking off. OR...maybe there is an issue with the shuttle valves?? The manual doesn't mention how to service them but I'm really tempted to take them out to make sure they aren't stuck open.

Any other thoughts are appreciated. Thanks

Click to expand...

Ayuh,..... Put it back in, 'n see if the drive works,....

Well Bondo that is great advice and is actually what I ended up doing this morning. I did remove the shuttle valve last night just to be sure it was moving smoothly. It was sticking a bit at one end so I cleaned the bore up to make sure that wasn't a problem. Anyways, long story short, it operates properly now. There was lots of air bubbles initially but it's clean and smooth now.