Trim Pump Runs But Trim Does Not Move

[thedukeryan]

I have a 1990 Alpha One Generation one out drive with a 5.7 350 engine. My current problem is that the trim motor runs but does not bring the trim down. It worked fine yesterday and has not been in the water since last weekend. With that said the hydraulic fluid is slightly milky. As mentioned though I was able to trim it all the way down and trailer it up last night. I attempted to change the hydraulic fluid by pumping out as much as I could with a siphon pump. Added new power steering fluid but still nothing. Any advice from the boat guru's?

 

[dubs283]

Re: Trim Pump Runs But Trim Does Not Move

well you definitly have a leak somewhere in the system, hence the milky oil.

can you stand on the drive while a friend runs the pump?

once you get the drive to move you will have to remove the trim lines and flush ALL the old oil out and locate the leak and repair it.

Mercruiser recommends 30 wieght oil for the trim system, not P.S. fluid

 

[thedukeryan]

Re: Trim Pump Runs But Trim Does Not Move

Ok I replaced the port side trim trim cylinder a couple weeks ago due to corroded threads. I drained what I thought to be all of the fluid but is it possible that there was enough moisture "in the pipes" to contaminate the new fluid I put in? I removed the hoses from the port cylinder with the trim all the way down. Let the fluid drain from the port side hoses and then hooked up the new cylinder. Does this sound correct? To drain ALL the fluid correctly can I just remove the hoses going to the hydraulic cylinders or is there a preferred method. Also excuse my ignorance but by 30 wt do you just mean a basic 10W-30 oil?

 

[thedukeryan]

Re: Trim Pump Runs But Trim Does Not Move

Another question... What are the likely spots for a leak? I know there are the hoses and connections going to the trim cylinders. How about the actual cylinder itself? Any other spots I should be looking? Will I be able to spot a leak by visable fluid coming out or would that just be to easy :-(

 

[dubs283]

Re: Trim Pump Runs But Trim Does Not Move

10w-30 is okay or SAE 30wt.

remove all lines going to the rams and flush old oil out. you should flush and refill and reconnect then run the drive up and down. do this operation a few times to get all oil out

do verify that there are no leaks anywhere in the system as well

 

[gadget73]

Re: Trim Pump Runs But Trim Does Not Move

Merc suggests motor oil for that? hm, why the heck do they sell Mercruiser branded trim fluid then? I run ATF in mine, but thats good to know. The original fluid does get horribly nasty. When I replaced my bracket, I dumped all that milky garbage out. Quite a lot of clear water had settled out of the oil as well. I always assumed it was PS fluid since the engine's color code thing on the cover indicated a yellow cap was for trim/ps fluid.

Could be the cylinders are seized up. I've had to rebuild them when they just wouldn't go anymore. Usually the standing on the drive trick makes it go down, but if a full fluid change doesn't make it work properly again, you're probably looking at a seal kit. Usually its the end cap seal that seizes on the shaft. Its a bugger to get apart without a shop press sometimes, but once you get it apart, its not that hard to rebuild really.

 

[thedukeryan]

Re: Trim Pump Runs But Trim Does Not Move

Ok... So I will be working solo tomorrow so unless I get lucky I probably cant get anyone to stand on the prop while I run the motor. Can I just remove the hydraulic lines to relive any pressure and then push them down myself? Also once the lines are removed do I need to cycle the pump or what not to "flush" the old fluid out? Last if it is the cylinder stuck can I salvage the weekend by forcing it down and hoping it doesnt stick again or is it gonna continue to stick no matter what. I know I can get new cylinders for $120 so i may just go that route if that is the problem. Just have big plans for the weekend and wanna try to save them even if its a temp fix

 

[gadget73]

Re: Trim Pump Runs But Trim Does Not Move

If the cylinders are seized, cracking the lines loose won't let it go down. It would be a useful test to see where the problem is though. It should fall under it's own weight with the lines loose at the cylinder.

If you want to use the pump to flush the system, then you need someone to activate the pump while you have the line in a bucket. Keep the trim bottle full though, otherwise you'll pump a bunch of air through the lines, and then you'll have to cycle it a bunch to bleed the air back out.

 

[thedukeryan]

Re: Trim Pump Runs But Trim Does Not Move

Ended up being from the water in the lines. I cracked the hoses upen and the cylinder dropped on their own. Not sure if this is the correct way but I removed the lines from both cylinders and manually cycled them to get as much of the old fluid out as possible. I then filled the reservoir and ran the pump a few times with the hoses connected. Re attached the hoses and again ran the pump up/down multiple times. Seems like things are working for now.