trim pump issues.....

[ScottinAZ]

ok, if there is a more appropriate area mods, please move this....

boat and trim system in question is a 1980 Galaxy with a 120 Merc engine/drive combo (MC-1 IIRC)

the trim WILL NOT go down on the switch.... I have traced it to a likely stuck shuttle valve on the "up" circuit that is not releasing the pressure and allowing fluid to return to the reservoir in "down" mode.....

since this is inside the pump, and as per Mercruiser and Prestolite is therefore unserviceable, I need to replace the damn pump.... most I see on Ebay when chasing the part number are just the motor and reservoir.... Mine are both good, its the pump module that is not working.....

since I cannot seem to source a pump at a reasonable cost, is there a way to retrofit a later Alpha One (gen 1 or 2) to this boat, and get it actually working.... The "new" pump specified uses inverted flare fittings on both "up" and "down" ports, dispensing with the idiotic plastic line that mine has (no biggie, the new hose I just installed from the transom to the reverse lockout is that size....

Where is the reverse lockout located in the Alpha pumps, is it internal to the pump valving, or is it still external like the old Prestolite high pressure/low flow such as I have.

I dont mind a bit of mickey mousery to get it working, and above all safe, but trying to find a complete working pump to directly replace mine at a reasonable cost (less than the value of the boat....) is seemingly impossible....

im about ready to do the unthinkable, and pull the pump off my other boat (OMC/Volvo drive) and make that work.....

 

[alldodge]

Need someone like @Bondo or @Bt Doctur maybe to help out

Changing from Pre Alpha which used a lockout to the newer Gen 2 or Bravo should be remove lock out and install new style pump in it's place. All the lock out functions are in the pump

 

[ScottinAZ]

Need someone like @Bondo or @Bt Doctur maybe to help out

Changing from Pre Alpha which used a lockout to the newer Gen 2 or Bravo should be remove lock out and install new style pump in it's place. All the lock out functions are in the pump

sounds good. I will need to physically leave the disconnected lockout there though, it acts as a fulcrum point for the upper/lower shift cable connection..... that is no biggie though....if the hose connections are the same 1/8 inverted flare, then its easy peasy electrically....

 

[kenny nunez]

If you remove the rams can you rotate the rods ? If you cannot then the real problem is the packing glands are corroded which binds them up.

 

[Bondo]

Ayuh,..... Does the trim motor run on the down switch,..??
If so, have a heavy friend jump on the drive, as you run the motor down,....

If that breaks it free, do what I do, when you run the drive up, 'n you hear the pump loading up at the top,.....
Run it down a second or two, to unload the system,...... it'll quit stickin' in the up position,....

Otherwise, yes, the new style pump, 'n lines just bolts into place,....
No reverse lock necessary, the valving is in the pump,....

 

[kenny nunez]

If you can get a pressure gauge that goes up to 1000 lbs connect it to the down circuit. You should be getting 7-800 lbs . If it is a lot lower than that there may be a 1/8” pipe plug in the side of the valve body. If you see one let us know. You might be able to adjust the pressure.

 

[ScottinAZ]

Ayuh,..... Does the trim motor run on the down switch,..??
If so, have a heavy friend jump on the drive, as you run the motor down,....

If that breaks it free, do what I do, when you run the drive up, 'n you hear the pump loading up at the top,....

Run it down a second or two, to unload the system,...... it'll quit stickin' in the up position,....

Otherwise, yes, the new style pump, 'n lines just bolts into place,....
No reverse lock necessary, the valving is in the pump,....

motor runs in both directions. from what I can tell, the check valve on the "up" side is not releasing pressure for the fluid to return to the reservoir. No amount of banging on it has freed it up, its stuck GOOD..... pressure and flow are good, once you provide a "return" (cracked loose hose) and the system runs as advertised. At this point, Im ready to throw the pump into the dumpster and just replace it with one that works. I will once again see what is available at a reasonable cost on Ebay, I refuse to pay over $1000 for a pump in a boat that isnt worth much more than that running.....

my normal end of run procedure is to run the drive up, put in the travel locks (which I have cut about 1/4 inch short of full length) and then run the drive down on them lightly to hold the drive up, and prevent it from falling..... I dont run the pump until it bogs in either direction. That said, in "down" the motor will run at full speed for a few seconds, then slow way down, and until recently, the drive would slowly come down.... now it just bogs, and doesnt move, once it gets a few inches down from full "up" (about long enough for the pressure on the return side to meet/exceed the down pressure from the pump......)

 

[ScottinAZ]

If you can get a pressure gauge that goes up to 1000 lbs connect it to the down circuit. You should be getting 7-800 lbs . If it is a lot lower than that there may be a 1/8” pipe plug in the side of the valve body. If you see one let us know. You might be able to adjust the pressure.

I dont have access to a gauge, but I am getting good flow out of a disconnected line. There are no pipe plugs in the valve body. Someone before me had dicked with the check valves in the control body, so that could still be dorked up, That said, there is no restriction in the control valve on the "up" side (down side return), its a straight through hole, and the check valve is deeper in the pump. according to service bulletins, that part is "not economically repairable" as per Prestolite, so its a disposable POS.....

 

[alldodge]

I am getting good flow out of a disconnected line

The line is disconnected and it still won't go down?
If that's the case then it's in the cylinder

 

[ScottinAZ]

The line is disconnected and it still won't go down?
If that's the case then it's in the cylinder

yes, it will drop like a rock when you disconnect a cylinder.

 

[alldodge]

ok, then it is the pump

 

[ScottinAZ]

ok, then it is the pump

yeah, I spent the last few days in the manual trying to make it not be the pump...... but its the pump... I pulled it off this morning and opened it up... full of crap, and the shuttle valve that controls the release of "up" side pressure in "down" mode is jammed solid.... no amount of convincing short of destroying it will allow it to move.... CONFIRMED KILL......

I rebuilt the rams two years ago now when I recommissioned the boat, so they should be good, but Ill give this a good flush while the pump is off to get any accumulated junk out of the lines and rams..... dont need to smoke a new pump

 

[Lpgc]

I'm not posting to try to advise people on this thread who I know have more experience than me... But if the pump is broken internally is it worth taking a look inside and see if it's something that could be fixed? My OMC Cobra (Volvo Penta SX) trim pump had a broken internal seal that allowed the rams to come down over time, I went inside and fixed it by putting in new O rings, all the check valves etc were accessible while I was in there and I had them all out, cleaned them all up.

 

[alldodge]

Opinion
Since it's headed for the trash I would take it apart to see if it could be fixed. That said, if it looks like it will be damaged doing so then it goes in the trash

 

[ScottinAZ]

according to Mercruiser service bulletins, these pumps are non-serviceable as per Prestolite. Aside from o-rings, there are no parts available, and the specs for the pop-off spring settings are not published in the service manual... that said, yeah, I took mine apart to see if it was just a simple stuck valve.... well, its a STUCK valve, and there is no way short of drilling the cover for it to try and get access.... removing the roll pin did nothing to get the cover looser....

I tend to not believe in "non-serviceable" parts, if it is something that can be easily unstuck, or parts "made" or cannibalized from another unserviceable unit, but in this case, short of the curiosity factor, its DONE..... further disassembly by force would damage further or outright destroy the part, and since I already have a new pump on the way, this one will get filed for "other purposes"..... never know when you may need a small hydraulic pump for some reason..... gut the valving, and you have a basic pump that you could plumb into any manner of external valving...... I am a certified Pack Rat, so NOTHING gets binned unless its truly shot......