Trim pump not working in down position

dmiles452

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I have a 1989 Alpha one mercruser stern drive and just this weekend the trim pump has stopped working in the down position. Unit comes up just fine but no downward movement. When trying to get the unit to go down, the pump sounds different than it does in the up cycle. The unit worked fine last year before I put it away for the winter. So what is the separation in the pump between the up and down cycles? Is there a seperate relay for each position. The reservoir is full.
 

Bondo

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I have a 1989 Alpha one mercruser stern drive and just this weekend the trim pump has stopped working in the down position. Unit comes up just fine but no downward movement. When trying to get the unit to go down, the pump sounds different than it does in the up cycle. The unit worked fine last year before I put it away for the winter. So what is the separation in the pump between the up and down cycles? Is there a seperate relay for each position. The reservoir is full.
Ayuh,.... Not sure which pump you have, as there's been a few,....

Is the drive still all the way up,..?? did you leave it up all winter,..??
If so, have a heavier friend jump on it, as you run the pump down,....
It might break free, 'n work again,....

When you run it up, do you run it up, til the pump loads,..??
If so, tap the down button a couple of times, so that the pump isn't loaded against the the check-valves,...
 

dmiles452

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The drive was up all winter, I do usually run it up until the pump loads. I will check later this afternoon to see what type of pump I have. I will post a picture.
 

Scott Danforth

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just have a heavy friend jump up and down when you are pressing the down button. you are mashed up against the end of the cylinder and the PO check valves are now stuck closed holding the drive up.
 

kenny nunez

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If your friend provides enough weight to get the drive to go down and it does not go down after raising it then the problem is the packing where the ram rods extend. Corrosion can build up between the “O” ring seals and the retainer nut. Sometimes penetrating oil might free up the rams.
Sierra# 18-2649. Power trim seal kit.
Mercruiser# 25-87400A2 seal kit.
It is easy to do and you do not have to remove the rams. Remove the self locking nuts and washers. loosen the front nuts and pull the ends off the stainless cross pin. Just un screw the retainer nuts, pull the rods out. You will lose some oil. Carefully remove the retainer bolt and piston, watch for the small springs on the piston and note which way it came off. Remove the “O” rings from the retainer nut and scrape the corrosion from the seal grooves. Do 1 at a time. Refill the pump with power steering fluid, cycle the pump a few times, you may have to add some fluid.
 

Bt Doctur

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19,178
access the pump, reverse the black and grey lines.the higher pressure should allow you to lower the drive.You may have to replace the end caps of the cylinders due to corrosion
NEVER store a drive in the in the full up or full down without relieving the pressure from full stop
 

Lou C

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That’s a habit I’ve had for many years when I had a shallow mooring spot; I’d trim up all the way & then just lower it enough to get the rear anode & end of the trim rams under water…
 

dmiles452

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Mar 31, 2014
Messages
65
just have a heavy friend jump up and down when you are pressing the down button. you are mashed up against the end of the cylinder and the PO check valves are now stuck closed holding the drive up.
Scott, I tried your method and it worked, drive will now go up and down. Thanks
 

crazy charlie

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Scott, I tried your method and it worked, drive will now go up and down. Thanks
Its a very good idea to raise drive all the way and grease the rams all the way and run it up and down a few times , each time spreading the grease back onto the ram.The grease will gather at the cap each time. Charlie
 

Scott Danforth

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Its a very good idea to raise drive all the way and grease the rams all the way and run it up and down a few times , each time spreading the grease back onto the ram.The grease will gather at the cap each time. Charlie
not needed, in fact it is not recommended. the wiper will remove all grease. the rods get lubricated from the hydraulic oil. the grease will just attract dirt and take out the wiper and seal.
 

Lou C

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Just rebuilt my originals. I had a couple of spares from fresh water regions. As long as you can get that cap nut off, it's not a hard job. The other issue on a salt water boat is getting the hydraulic hose fittings loose. One did not want to budge, so instead of making a problem, I took off the caps of the rams on the boat, and used the better condition rams from the spares, with new seals with my original cylinders on the boat. Much easier that way. The old rams were pitted, and the eyelets that hold the drive up were REALLY corroded. One was leaking and when I really looked at those eyelets, I'm like that's BAD. 20 years of salt water moorage and I think OMC should have put anodes on them too! They did last 36 years though! I've owned the boat 20 years and I don't think they were touched before I bought it.
the main things to check are the ram to make sure it's not pitted, and the inside of the cylinder, same thing.
BAD:
Old trim ram.jpg
this took heat, patience and brute force....
Trim ram cap removal.jpg
what was left of the corroded trim ram eyelets, rams were also pitted
Corroded trim eyelets.jpg
finished job with fresh water parts & new seals on my old trim cylinders
Trim ram rebuild.jpg
Refilled the cyls as I assembled them and filled trim pump, then cycled it 5 times to bleed out air, and then refilled with tilt n trim fluid
the challenges of 20+ years of salt water moorage.
 
Last edited:

Scott Danforth

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the AQ 290 series VP drive has the pins for the rams accessable only when the engine and drive are pulled (almost to the point of removing the transom shield. ) the easiest way to repair them is on the boat.
 

Lou C

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When I reinstalled the trim caps I put a bit of Evinrude Triple guard grease on the threads, it helps parts to not seize up in salt water use.
 

Scott Danforth

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permatex #3 works too, make sure its after the last o-ring
 

crazy charlie

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Just rebuilt my originals. I had a couple of spares from fresh water regions. As long as you can get that cap nut off, it's not a hard job. The other issue on a salt water boat is getting the hydraulic hose fittings loose. One did not want to budge, so instead of making a problem, I took off the caps of the rams on the boat, and used the better condition rams from the spares, with new seals with my original cylinders on the boat. Much easier that way. The old rams were pitted, and the eyelets that hold the drive up were REALLY corroded. One was leaking and when I really looked at those eyelets, I'm like that's BAD. 20 years of salt water moorage and I think OMC should have put anodes on them too! They did last 36 years though! I've owned the boat 20 years and I don't think they were touched before I bought it.
the main things to check are the ram to make sure it's not pitted, and the inside of the cylinder, same thing.
BAD:
View attachment 398425
this took heat, patience and brute force....
View attachment 398426
what was left of the corroded trim ram eyelets, rams were also pitted
View attachment 398427
finished job with fresh water parts & new seals on my old trim cylinders
View attachment 398428
Refilled the cyls as I assembled them and filled trim pump, then cycled it 5 times to bleed out air, and then refilled with tilt n trim fluid
the challenges of 20+ years of salt water moorage.
Hey Lou,I have never seen corrosion that bad, not even close on 30+ years of mercruiser.I put collar zinc on my lift cylinders.you may want to considerhttps://defender.com/en_us/martyr-limited-clearance-sacrificial-shaft-donut-collar-anode?utm_id=150171837047&utm_campaign=19735474073&utm_source=google&utm_medium=paid&utm_content=649561344444&gad_source=1&gclid=Cj0KCQjw0ruyBhDuARIsANSZ3wqWooS8zp8qnTbSdIL5c3uQYJWY6u6ZDweHYauyiKtHYLTp_ChpR7saAlziEALw_wcB#493=47340&615=29619
 
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