Trim Pump woes

[ShorePounder]

I'm hoping someone can help me out here. I'm in the process of rigging my old boat for a V6 after having an inline on it all of last season. I picked up a used square motor trim pump that was in decent shape. The pump internals cleaned up well and appear to be in satisfactory condition. The problem I have is with the motor itself. When I first installed the pump in the boat and started the filling and bleeding process, it would only run for short bursts. The more frequent you tried to run it (in either direction) the shorter the bursts. Let is sit for a bit and you could get it to run for 5-7 seconds. WOO HOO I suspected the thermal protection switch, but the outside of the can never felt hot. I pulled the motor apart and cleaned the commutator and checked the armature for damage. scuffed the faces on the brushes a bit and put it all back together. Same thing, only slightly better. In frustration I yanked the thermal protection swith out and ran the pump that way. I was at least able to fill and bleed my trim system then. Only problem is that after a full run in one direction, small tendrils of smoke can be seen coming out of the top of the can and the exterior of the can is hot. There's some serious issues with this motor right? Well a week goes by and I stumble across a killer deal on a brand new frame and armature for my square motor. Well I just replaced the frame and arm and I'll be damned and dipped in crap if it ain't doing the EXACT SAME razzle-frackin-clock-flockin-#%*&#^*# THING!! Short burst, nothing over 2 seconds. Hold the button and its like your bumping the trim in consecutive intervals. What's the deal with the thermals on these things?? Is there something I'm missing that's creating heat like that? I've got good grounds and nice heavy cable for hot and ground. The solenoids seem to work fine. Help guys, i'm pulling my hair out and if you've ever seen me without a hat, you'll know I ain't got much left as it is.

Me and trim pumps don't seem to get along. One of the biggest issues I had with the inline on this rig was the old Oildyne POS trim pump that was on it.

[Techno]

My guess is the pump is shot. Kind of like hooking a mouse up to a horse drawn wagon. The load is too much so the motor draws more amps and cooks itself.
I guess if you can turn it by hand that should tell.

All the electrical guts were changed out so the motor aint the problem. Either the wiring is wrong or the driven machine is bad.

[Bruster]

I'll bet your motor will do the same thing with out driving the pump.<P>
I have a couple of motors like that in the garbage pail. I replaced the mess with new Arco motor and problem gone!! <P>
Watch eBay.eBay

[ShorePounder]

Actually Bruce, you're right. Before I rebuilt it, it did just that. I dry fired it off of the pump and it did the exact same thing. I yanked out the thermal breaker and that solved that. Those things must have a shelf life or something. The replacement was brand spanking new( or NOS however you want to look at it) Quicksilver replacement. The ARCO motor is a round one that fits that application right? Not that its an issue, I was just thinking that there may have been something inherently wrong with the square motor's design.

Techno, I was thinking along that line, but I can turn the pump by simply pressing my finger on the pump drive and twisting. It's how I've been lining up the pump and motor shafts. Certainly if its that easy to turn, it can't be all that bad. Another thing I may not have mentioned, is that it does this immediately, not after it's been run a bit. I've got better grounds than a PGA golf course and for now I'm using the cable I intend to run to the starter on the motor.

[Superdave]

You may want to remove the bottom and check the filter. May be clogged causing the motor to work hard. Just a thought.
Dave

[ShorePounder]

The strainers were shot when I got the pump so they were replaced. I cleaned the pump out to make sure no strainer debris made it into the pump.

[Techno]

The frame is the stator coils or field coils? I figure with all the wiring changed it has to be something else. Can the motor be run without driving the pump?

[ShorePounder]

I'm suspecting that my battery is bad. I'll have to confirm this this afternoon. It shows 12V, but never reaches full charge according to my battery charger. If the voltage drops dramatically under load (which will happen in the case of a bad batt) the current will go up (ohm's law) The high current may be what's tripping out the motor. The motor may not have been bad to begin with. It may have been the battery the whole time. I'll know more later and I'll post more then.

[Tom D.]

Reverend,
I had the same problem you did. Pump would run a few seconds then stop and shorter times after that. I took the motor off and it ran fine (powerful little sucker). As it turns out it was the pump its self. I took it apart and the little housing that holds the gears were worn on one side. One of the gears gets cocked a little and bingo locks up. The housing that holds the gears is made of aluminum and the gears are steal and if there not perfectly vertical they will lock up. The motor puts alot of torque on the gears. I got another pump and switched the little housing and gears and it works great.

Tom

[sosmerc]

Could you try running the pump temporarily with a portable drill motor just to see if the pump binds, or locks up?

[ShorePounder]

Got it taken care of (I think) The pump works and works efficiently. The motor does not get hot after a full trip in one direction (something it was doing before I rebuilt it). I threw out the damn thermal breaker. Ran the trim up and down a couple of times and the can was warm, but not hot and there was no smoke. I thought it was the battery, but it tested OK so I threw it on one of the big chargers at Auto Zone that charges and tests. I got a green light there too. Dunno. The only conclusions I can come up with that make sense are:

1. There indeed was a problem with the old motor armature and field causing it to generate serious heat during operation.

2. Those bi-metallic thermal protection breakers must have a shelf life. The metals must weaken or oxidize or something that makes them less effective as time goes on.

Thanks for all of the help and suggestions.

[Talon2.5]

cool, ya get the rest of the wiring done? was gonna call ya last night but fell asleep in the chair

checkmate, thats good info to remember for future troubleshooting

[ShorePounder]

I have the pumps wired, fuel, bilge, and trim. I wrapped the harness as the sun left me and the skeeters began to join me. I've got to do the AZ thing tonight so there won't be much in the way of progress made until tomorrow. Things are quiet here at work, I should have brought the boat in. I could have at least got the fuel tank mounted and plumbed.

[Psyco]

The brushes usually wear on these before the armature and windings go. Merc doesn't sell brushes. Watt to do? Go to ya local starter alternator shop and get a set of brushes for a Tecumseh starter. Chuck the armerture up in a drill press,turn it on, and use a file to clean up the area where the brushes ride and the rest of the armature till it's nice and shiny. Get out the trusty solder gun and install your new brushes. Use that liquid rubber electric tape to insulate the connections. Put a dab of silicone grease in the upper bushing. If the shaft is worn where the seal rides,use a little JB Weld to fill and chuck it up in the drill press adn get to werk wiff the file. Seal kits are available from Merc. Use a smidgen of RTV around the pump housing (careful,not too much).
BENCH TEST!!!!
BENCH TEST!!!!

Did I say BENCH TEST?

For sum reason,these things don't always go together right. You'll get it all together,put the juice to it and NOTHING!!!! Loosen the top cap,retighten and the SOB werks. I'm sure there is sum super technical explanation,but at this point I don't give a damn.

Good Luck and have fun.

[ShorePounder]

Thanks psycho! Great info. I'd wondered about the brushes. The old oildyne's used off-the-shelf .25x.25 brushes and were easy to find.