prestolite power trim pump help

[sarantis]

At the end of last season the power trim didn't work at all.With some raps it worked but some times got stuch.I could hear the noise of the motor but the stern drive didn't go up or down.I took the pump out and dissasembled to look first the brushes.The one wasn' t properly positioned.I fixed it .I performed the tests described at the manual.Up to here everything OK.
But,
When I took out the 8 screws of the valve body out and open it apart from the oils a tall cap and a screw exactly the same with 8 screws appeared from nowhere. Ok the tall cap was easy to find its place but the screw? I read all the manual but nothing.The only place i didn't searched is bellow the hydraulic mechanism as the manual didn' t refer anything about it.So i reasembled the unit believing that this screw is useless!
My problem now.Checking again with the battery directly to the motor terminals and a wire to give +12V to the solenoid:
the one cylinder did move the other not.I did the process to take the air out but nothing.It's characteristic the sound of the one cylinder trying to push the other.Grrrr, Grrrr.
What am I doing now?

 

[Haut Medoc]

Re: prestolite power trim pump help

I would suggest that you loosen the nuts on the exterior trim hoses on the problem cylinder after moving it to the full 'up' position....
See if you can get any movement at all....
They will freeze up due to corrosion.......
Refresh my memory...
What year is your set-up?​

 

[sarantis]

Re: prestolite power trim pump help

Thanks you appeared master!
It's 1978.I thought of doing this but the nuts were stuck.That's why i connected the two cylinders todether believing that the one will unstick the other.So if by taking out the hoses it doesn't move have I to dissasemble the bad cylinder ?

 

[fendersfender]

Re: prestolite power trim pump help

ok, i'm confused.....what do you mean by "connected the two cylinders together"????....if the pump runs and is trying to move the drive, then i would assume that one of your cylinders is bad and needs to be replaced...will the drive move at all...up or down???? some more info would be helpful....make and model, drive, year etc. a service manual would probably help you troubleshoot your problem

 

[sarantis]

Re: prestolite power trim pump help

Thanks for replying,
If you pay more attention to my thread you will see that I follow the manuals'steps to the possible degree.(e.g. i don't have the tools to carry out the pressure test).
Any way my problem seems to be coming to an end.I dissasembled the bad cylinder (I went to a car mechanic who had a big steady vice and a huge wrench and with applying heat we opened the cylinder ).
The end cup was completely stucK to the rod.
I 've already ordred a set of O-rings etc. and I hope that it will be fixed.

****To Bond O*****
Don't misanderstand me but one more problem made me about to loose my patience!As about your puting a new A1 is this a hint to me?I 'm joking!
I think you mean that's .a matter of bad sychronization.Night for me is day for you and vice versa.Anyway once more I found a solution again and I thank all of you

 

[sarantis]

Re: prestolite power trim pump help

Sorry to bother you guys but now i have another problem.I fixed the bad cylinder( model year 1978 mercruiser A1)and now the sterndrive goes up (out)perfect but none cylinder goes goes in.Can one cylinder influence the other?
(Are they connected to thesystem in series or in parallel?)
I'm asking that because I've a small suspicion that the supposed good one had a small difficulty in going in.
What do you advise now?May it be the pump?

 

[Haut Medoc]

Re: prestolite power trim pump help

Each trim cylinder has two hoses going to it, correct?
I think you may have reversed the hoses on the one you were working on......​

 

[tommays]

Re: prestolite power trim pump help

The PUMP is a LOT more complex than it looks

ITs pushs out with ABOUT 2000 PSI and goes back in with ABOUT 600 as if you HIT something it has to allow the drive to raise up

And when you stop triming the checks in the pump have to hold against all the pressure the outdrive is putting on the cylinders


Merc has a set of test guages that they connect to the pump to check the up and down presssure so your not working in the dark


http://www.boatfix.com/merc/Servmanl/6/6C5R3.PDF


this may not be the exact manual BUT shows how to test the pump for the correct pressures and holding abilty


Tommays

 

[sarantis]

Re: prestolite power trim pump help

I was just reading the trouble shooting guide and i read this possible fault about reversing the hoses but i think i put them correctly.do i miss anything if i try the reverse connection? But you didn' t tell if the cylinders are in series .I have disconect the one from the sterndrive and an answer to that would help me identify if it's a pump problem or not because as a matter of fact when feelig with new oil in came up with some salt

 

[tommays]

Re: prestolite power trim pump help

You need to test the pressure like the manual shows or is is just a WAG

DONT X connect the hoses if you get one cylinder going UP and one DOWN it will destroy the mounts


Tommays

 

[sarantis]

Re: prestolite power trim pump help

Sorry Tommays but I have to go on without the pressure test.But why you don't answer me that question.Supposing we have one good pump and two cylinders disconnected from the rear point of the sterndrive,one good and one bad.Will the good one move in or out or it may be influenced by the bad one?
And what means WEG?I suppose something funny,bad,silly?

 

[tommays]

Re: prestolite power trim pump help

WAG = WILD AZZ GUESS

Yes if one cylinder is leaking it will affect both BUT it would have to be a REALLY bad leak to cause your problem

When the boat is out of the water it takes very littel pressure to move the drive


All you need to get is a 3000 PSI guage and a T-fitting from a HYD shop

(you dont have to buy the full merc test tool)

and you can use it like the manual shows so you KNOW if you have presssure OR not

Tommays

 

[sarantis]

Re: prestolite power trim pump help

Thanks for trying to put me to the right way but I'm so tired with the repairs of this boat.The power trim is only the tip of the iceburg,though nesecesary to go.Anyway I'll rest for a while and I let you know.

 

[melton120]

Re: prestolite power trim pump help

I just bought a 1980 mercury 115hp outboard with an old pretolite power trim pump on it. I can get it to go up and down but after doing this once it will stop and move a little every so often. all solenoids click . When checking everything I noticed it seems to be draining the battery. going up once or down once it is draining battery by about 25%. So I believe after moving it doesn't have the power to move again. Any one have any ideas of what this is and how to fix ?


I have checked all connections and armature ,brushes . Everything is connect like the wiring diagram so Iam lost please help.