Oildyne Trim Pump

Joe Manor

Seaman Apprentice
Joined
Nov 23, 2013
Messages
37
Hello all. My first post here. Hoping to get some help. I have a 1989 Mercury Alpha 1 and was on the water the other day and my outdrive got stuck in the up position. I had to use my trolling motor to get back to the dock and on the trailer. I looked in the reservoir and the oil was milky like it had water or air in it. Thought it might just need clean fluid and a bleed. I do not have the proper tools to do a pressure check. Here is where it's at. I can lower the unit all the way down but if I try to physically hold the outdrive while trying to lower it (wifes help) I can actually keep it from dropping down. When I raise it up I can literally stand on it and it will lift me up. Im assuming I do not have adequate pressure for the down side. I have not replaced any relief valves or any parts but Im not sure what the problem is. If I raise the motor all the way up until the pump really bottoms out then I cannot lower it anymore. If I loosen the pressure lines at the cylinder for a second to relieve pressure then I am able to lower the unit. I can raise and lower the unit over and over again as long as I don't go all the way up. Still though, it has no power pushing it down. really weak. It used to almost want to lift up the boat off the trailer if it ever hit the ground. It is an old unit. Should I replace the entire assembly? I found some aftermarket units for $300 in ebay. Do any of you think it might just need a down pressure relief valve, pump rebuild kit, or adaptor? Any help would be great. Thanks in advance.

Joe
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,267
Re: Oildyne Trim Pump

Hello all. My first post here. Hoping to get some help. I have a 1989 Mercury Alpha 1 and was on the water the other day and my outdrive got stuck in the up position. I had to use my trolling motor to get back to the dock and on the trailer. I looked in the reservoir and the oil was milky like it had water or air in it. Thought it might just need clean fluid and a bleed. I do not have the proper tools to do a pressure check. Here is where it's at. I can lower the unit all the way down but if I try to physically hold the outdrive while trying to lower it (wifes help) I can actually keep it from dropping down. When I raise it up I can literally stand on it and it will lift me up. Im assuming I do not have adequate pressure for the down side. I have not replaced any relief valves or any parts but Im not sure what the problem is. If I raise the motor all the way up until the pump really bottoms out then I cannot lower it anymore. If I loosen the pressure lines at the cylinder for a second to relieve pressure then I am able to lower the unit. I can raise and lower the unit over and over again as long as I don't go all the way up. Still though, it has no power pushing it down. really weak. It used to almost want to lift up the boat off the trailer if it ever hit the ground. It is an old unit. Should I replace the entire assembly? I found some aftermarket units for $300 in ebay. Do any of you think it might just need a down pressure relief valve, pump rebuild kit, or adaptor? Any help would be great. Thanks in advance.

Joe

Ayuh,.... Welcome Aboard Joe,.... It does sound like yer pump is tired,...

I believe iboats sells the newer replacement pumps,... Try the links at the top of this page,...

The stickin', at full Up, is probably the pump valves,...
Lotta folks go up til it crowds out, 'n leave it that way,...
Ya should tap the Down button a few times to relieve the over-load pressures from the valving,...

Ya gotta figure out where the Water came from though,...
 

Joe Manor

Seaman Apprentice
Joined
Nov 23, 2013
Messages
37
Re: Oildyne Trim Pump

Yes, I have the manual. Looks like a bit of work to replace parts and since it is 25yrs old I figure I might as well replace the whole assembly. I plan to sell this boat in the next year or two and don't want to spend a lot of money on it. Do any of you have any experience with the cheaper replacement units?
 

tpenfield

Moderator
Staff member
Joined
Jul 18, 2011
Messages
18,406
Re: Oildyne Trim Pump

Welcome to iBoats, Joe . . .

Since you are seeing milky oil in the reservoir, check all of the fittings to be sure that you do not have a leak. You just want to be sure it is the pump ( and not the trim cylinder(s) )before you start buying replacement parts.
 
Last edited:

Joe Manor

Seaman Apprentice
Joined
Nov 23, 2013
Messages
37
Re: Oildyne Trim Pump

Im also not 100% sure which exact part I have. Do you guys know how to find it? The stickers are not on the unit anymore. It does look just like the one in the above link, has screw type connections (flares) and has a round plug on left with a hose clamp holding it on.
 

Joe Manor

Seaman Apprentice
Joined
Nov 23, 2013
Messages
37
Re: Oildyne Trim Pump

Welcome to iBoats, Joe . . .

Since you are seeing milky oil in the reservoir, check all of the fittings to be sure that you do not have a leak. You just want to be sure it is the pump ( and not the trim cylinder(s) )before you start buying replacement parts.

I was assuming that if the cylinders were faulty it would not have so much force going up and so much less going down. Am I wrong here?
 

tpenfield

Moderator
Staff member
Joined
Jul 18, 2011
Messages
18,406
Re: Oildyne Trim Pump

I was assuming that if the cylinders were faulty it would not have so much force going up and so much less going down. Am I wrong here?

Kind of depends where the leak is. Since you have milky oil it is a possibility that you have a leak in the hydraulics . . . the trim pump may be OK. Just check your fittings, etc. for signs of oil/fluid.

Also I sent you a PM.
 

Joe Manor

Seaman Apprentice
Joined
Nov 23, 2013
Messages
37
Re: Oildyne Trim Pump

The fluid has been milky for years. I never messed with it. It has always worked great and I have never seen any signs of any leaks other than the milky oil. Maybe it is detergent or something. Still, when I replaced it with new fluid it still has the same issue.
 

tpenfield

Moderator
Staff member
Joined
Jul 18, 2011
Messages
18,406
Re: Oildyne Trim Pump

The fluid has been milky for years. I never messed with it. It has always worked great and I have never seen any signs of any leaks other than the milky oil. Maybe it is detergent or something. Still, when I replaced it with new fluid it still has the same issue.

Got it, thanks. Here is what I did to test my trim pump when it went south earlier this year. Tied the trim lines together and verified that the outdrive stayed in a raised position overnight.

IMG_2436.jpg
 

Joe Manor

Seaman Apprentice
Joined
Nov 23, 2013
Messages
37
Re: Oildyne Trim Pump

Thanks, Yeah, that is a different issue all together. My outdrive does not leak down ever. If it did then yes, connecting the lines to rule out the cylinders would work but if they never leak down then there is no issue there. Must be my pump.
 
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