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  1. #1
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    Default rebuild instructions for pre-alpha hydraulic trim pump

    Is this a DIY? Help me get back on the water!

  2. #2
    Petty Officer 2nd Class Big Boat Bay Buster's Avatar
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    The warm weather is kicking in where you are. Plenty of good used units around, check E-bay or your local boat yards.To me, thats your fastest, easyest way to get back on the water.
    What exactly is wrong, mabey the guys here can help out. Go to the sticky and download the manual and have a look--its pretty involved if u ask me.
    Chris

  3. #3
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    A bit vague in your discription of your pump.
    Don S.


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  4. #4
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    1975 I6 165 HP Trim Pump very bad photo attached

    Symtom: High amount of fluid came out when activating pump. Black house is new and checked. looking back at it now, it would have made sense to put a mirror under pump and test to isolate leak. I did not, thinking I would find the leak upon removal. There are three holes at the bottom, One had a black hose, threaded line. The second was on a copper fitting and was a plastic hose. There was a third hole and nothing was in there and I am thinking that was some type of return.





    http://i925.photobucket.com/albums/a...t1968/pump.jpg
    Last edited by Don S; May 25th, 2010 at 02:22 PM. Reason: Changed to link Photo to big. Keep to 640W max

  5. #5
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    As I recall, there is only 2 lines on those pumps. Is it your original pump, or is this a replacement you picked up?
    Don S.


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  6. #6
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    This is the original, and there were only two connected and when I replaced the black line two years ago I think there was only two. If that is true, what is the the third unthreaded whole for and why would fluid leak from there?

  7. #7
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    Red face Re: rebuild instructions for pre-alpha hydraulic trim pump

    and sorry for using whole instead of hole, I am not a fan of misppellings that occur on forums.

  8. #8
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    One of those holes ins't a "hole". It's hard to understand but there are no threads in the casting and it doesn't go into the housing. I spent 15 minutes one time trying to thread a hydraulic line into a spot that had no threads and didn't even have an opening despit it looking that way from the side. I had to remove the pump from the floor to discover that, lol.

    Should just have one of the braided lines and the plastic line that runs up to the trim sender.
    1976 Mark Twain 200VBR w/Mercruiser 233 (Ford 351w) "Heart & Soul"

  9. #9
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    The valve body has "O" rings for sealing.

  10. #10
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    Default pictures help-here is the info

    EDIT: RESIZE PICTURE TO 640W Max.

    Connections: One at the brass elbow next to the non threaded hole and the other on the other side, which is the up or higher pressure hose. I did not see where it was leaking from, but I would have to bet it is the hole next to the brass elbow? Is that like a weep hole similar to water pumps, i.e. it leaks early and you know you need to replace?

    If it is leaking from there, is this an easy rebuild? I would like to go the rebuild route since this motor looks in better shape than a used one and if I rebuild I know what I have.
    Last edited by Don S; May 26th, 2010 at 09:52 AM. Reason: Removed HUGE picture ...... again.

  11. #11
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    http://i925.photobucket.com/albums/a...esizedpump.jpg

    Resized photo. My sincerest apologies since I know the importance of keeping space avail and not have huge photos posted.

    EDIT: Picture still too big. It's 1023 wide, please resize to 640 wide, or just post them as a link.
    Last edited by Don S; May 26th, 2010 at 10:31 AM. Reason: Picture to big again

  12. #12
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    I also have one of these pumps...1977 Starcraft Capri. I had trim problems (long story about a sand bar) and fought with it for about 1 year cause I was so new to all of this.
    It's a Prestolite pump. looks in fairly good shape. On the bottom there is a "dog bone" held on by 4 bolts. One of the hoses connects through this dog bone. If you take it off of the pump you'll find 3 o-rings.
    I blew one of these o-rings and it leaked from the side of the dog bone where it mounts to the bottom. since the o-rings are centered the leaking fluid can go in just about any direction but more than likely it will leak from the side where the o-ring is ripped/damaged.

    There are only 2 hoses. one (I think is high pressure side) goes down to transom...other comes from reverse lock (on shift plate , low pressure side)

    I do see other "holes...not threaded" that do nothing. I bought the bottom end on ebay for $75 since my motor was good. I received the reservoir and everything below it for this price.

    It turns out the reason I blew the o-ring is that the reverse lock adjustment moved (sand bar I think) and the reverse lock would not let my drive go up. Down worked fine but up strained the pump and barely moved the drive. I left the up switch on too long and pow o-ring blows out the side of dog bone, it was hard to trace cause it leaked somewhere different every time.
    Hope this helps,
    Sean

  13. #13
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    yep, that's the dog bone...

  14. #14
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    First off, thanks for the reply, I will be opening this up tonight and was give then schematics earlier today. So if it was just the o-rings, why not replace these instead of buying new bottom? I am checking to see if I missread your post, but was there damage due to the leak or a leak was caused by damage?

    Any recommendations on where to pick up the o-rings?

  15. #15
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    Plus I am sure I will need a gasket or two.

  16. #16
    Honorary Moderator Emeritus Don S's Avatar
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    Here is what your picture should look like at 640 Wide.

    Attached Images Attached Images
    Don S.


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  17. #17
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    After hitting a sand bar (depth finder malfunctioning, bow queen wasn't watching ) the second time I ever drove my new old boat (my first boat ever) on vacation several things happened...leaking trim cylinder first, couldn't patch it or afford replacement, so a "boat mechanic" in Ocean City said to just use brake line plugs at the dist. block on transom to eliminate that cylinder...boat will trim fine with one cylinder...this worked for 30 seconds on trailer. After running up and down twice things working so far but third time going up "blam" ! loud pop and fluid spraying violently by trim pump...I think I just blew the line...last day of vaca so I leave it be and spend time with family.

    Once I get it home I order hoses and 2 trim cylinders on ebay (originals were old and corroded) guy said he has pump also for $75...that it will probably go soon also. I figured for $300 replace the whole system for insurance. After installing everything, now no leak but trouble going up.

    I read, read and read some more (thanks Don for the manual) I discover the majic o-rings. Soooo just to be curious I replace the o-ring in my old pump, reinstall old pump (they sell kits on mercstuff.com $15 or so for all gaskets/ o-rings) put the drive in forward (not running) to make the reverse lock position change on shift plate and presto everything works great! Now I have 2 complete pumps.

    Here's the short answer...I believe you can get an o-ring (if yours is indeed blown) either from mercstuff OR maybe from a local hardware store (take yours to match) and your back in business after 5 minutes it takes to remove dog bone and replace o-ring and the .50 cost for the o-rings. It may not hurt to take reservoir off and clean out and there's a screen under the metal cylinder that could use cleaning, also not hard to do.

    From what I've read and seen here I DO NOT recommend rebuilding...lots of small PITA parts to lose or reinstall incorrectly, not worth $75 for the trouble.

    Wish I knew all this a year ago but welcome to boating! Thanks to all who've helped me here, I'm quickly understanding the workings of my new hobby.

  18. #18
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    also..from the photo it looks like one of the screwholes on the corner was filled in, it may leak from the reservoir (not sure) without that screw being tightened on the corner...

  19. #19
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    Thanks a bunch for your help: when I stated reubuild, repair might be the better statement. Can I pull the dogbone, replace o-rings and reinstall? What manual are you referring to that Don sent? I have a prestolite rebuild info. but not the manual.

    As a somewhat decent backyard mechanic, I have a snap on container of various o-rings, are marine o-rings any different? I would think not since handling 10-30W oil or similar.

    I would assume there is a dogbone basket, correct?

    This boat is on its last legs and my goal is to get one more year out of it and do not want to put any $$ into it. (but then again I might say that next year)

  20. #20
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    yes on replacing the o-rings...
    not sure differences between "marine" o-rings but mine works fine so far.

    no dogbone gasket...o-rings seal the mated surfaces. It can't be easier to replace them. I did all my work while the pump was still mounted.

    If you pull it apart easy the long thin square gasket can be reused.

    The manuals are located at the top of the homepage for this forum, I use manual #2 since I have a 1977 Starcraft.

    Be careful though...once you dig into the manual you'll start to find the solutions to all the problems to those little quirks that can be fixed and so the obsession begins...LOL

    I've gone from just need old boat to take the family out a couple times fishing and boating to I want to completely restore this old girl and make her sweet...that's why we call her "Sweetness"

    Good Luck
    Sean

  21. #21
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    Default Re: rebuild instructions for pre-alpha hydraulic trim pump

    TOok off dogbone and all four o-rings are there, one looks a little worn, but should not be giving the bypass/leak that I was experiencing. Like it was earlier stated, I think the problem is internal above the dogbone. I will disassemble futher today and add photos (properly sized) and see if this sheds so light on the repair.

    If anyone has an older prestlite power trim pump and help me avoid further anguish it would be appreciated.

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