Trim Cylinders Keep Exploding!!!

75Carver

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Joined
Oct 25, 2007
Messages
4
I have a 1975 Carver Santa Cruz that I have been completely rebuilding yet taking it out every now and then when I can. It has a 225 HP Ford 302 Engine with a pre alpha gimbal and it now has a SE106 outdrive. The trim use to work great until one day the port trim cylinder popped on the side. Since then i have gone through 4 sets of cylinders in 2 months. Grant it, i bought all of these sets used but was told that they were working when they took them off. I would then put them on the boat and it would work fine for a day or a week then POW!!! busted. I have probably spent about $15,000 restoring and about 2000 hours of my time invested in this boat and this trim has gotten me so agitated. Me and the wife are on vacation this week so that we can boat all week in the Ohio river. Right now it works but I can already feel to much pressure, and slow. It always goes down. Always messes up when trimming up. I have the old 3 button trim switch in cabin and ran a mom togle to the flybridge. Bypassed wires so that i can trim in nuetral. So if you have any ideas hit me.
 

rbh

Fleet Admiral
Joined
Mar 21, 2009
Messages
7,939
Re: Trim Cylinders Keep Exploding!!!

check and see if your system has a preasure bypass valve?
rob
 

Howard Sterndrive

Rear Admiral
Joined
Nov 5, 2008
Messages
4,603
Re: Trim Cylinders Keep Exploding!!!

somethings preventing hydraulic fluid from exiting the rod end.
The pump pumps fluid in the base end and creates what hydraulic engineers call a "pressure intensifier", which turns 1500 psi into 3000 or more in the trapped rod end.
The bottom illustration shows what is happening. Red oil is coming from your pump, the trapped oil is purple... notice that the pressure has doubled? kapow.
intensification.jpg

Something is wrong in your trim pump unit, not letting oil out of the rod end.
 

Bondo

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Staff member
Joined
Apr 17, 2002
Messages
71,459
Re: Trim Cylinders Keep Exploding!!!

I have the old 3 button trim switch in cabin and ran a mom togle to the flybridge. Bypassed wires so that i can trim in nuetral.

Ayuh,.... You must have by-passed the Reverse Lock unit on the transom....
The pump is now putting Full pressure into the cylinders,+ the oil has No where to Go...
 

75Carver

Recruit
Joined
Oct 25, 2007
Messages
4
Re: Trim Cylinders Keep Exploding!!!

well, I've worked on it all day and found that I had the reverse lock valve on wrong so I went ahead and bypassed that straight into my trim sending unit. It appears to be working. My gauge does not go all the way up showing that it is trimmed all the way up. Isn't the trim supposed to stop working when it is trimmed all the way up and down? The motor still continues to pump which seems like it would blow my cylinders still. with no gauge on the flybridge it is impossible to know where i am trimwise. let me know if you all have any ideas. Good call on the reverse locking unit Bond-O.
 
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