Trim Pump Pressure Relief Valve
 

Guys, I need some help. I built a tunnel tab with a pair of trim tabs and a plate. I am using an Oildyne pump that made so much pressure it blew off one of the cylinders and ruined the threads. Rounded them and they are now worthless. I am making new covers for the cylinders that are a lot beefier with thicker walls and deeper threads.
My problem still remains too much pressure from the pump. On my drive pumps, the sound changes when the drives are all the way in or out and I assume there is a pressure releif valve built into them that is not in the Oildyne pumps.

How do I add a pressure relief valve to this pump. I hope this picture works.


thanks
Shawn

Re: Trim Pump Pressure Relief Valve
 

There's a relief in that pump.
Just need weaker spring in it (or shorter spring).

Re: Trim Pump Pressure Relief Valve
 

here is the pressure relief valve. The pressure range should be 2200-2600 on the "up" side. You may be able to ignore the warning and adjust the relief valve.

Re: Trim Pump Pressure Relief Valve
 

A picture is worth 10 words, ok maybe more.

Adjust it till you haver the pressure you need. Remember when the blue wire is hot the high pressure side is pressurized. Clip the spring if yo have to, but just try backing it off. We use these for hatch lifts, and if you don't lower the pressure and have a party going on back on your hatch it will either dump everybody overboard or break something. It helps to hook a gauge up to it, should be 3000 PSI max range. We only run 600 PSI or so for the hatches.

Re: Trim Pump Pressure Relief Valve
 

Ok I guess we are talking about the valves inside the pump. What are the large hex nuts on either side of the pump for?. I know they have a spring and ball under them.
What direction does one adjust the valves to increase the pressure?

Re: Trim Pump Pressure Relief Valve
 

Side ports are check valves. One is up and one is down.

Re: Trim Pump Pressure Relief Valve
 

The competition-tab/outboard pump you have in the picture is set to over 3400psi on the high pressure output side (UP) and about 1800psi on the low pressure output side (DN). If you order the replacement relief valves (as shown in the pictures above), I think they are set to the Bravo relief pressures by default, 2000+ on the UP side, 400-600psi on the DN side. The standard tab pumps that come with K-Planes are about 1600-1800psi on the UP, 600-800psi DN. Keep in mind that these pressures are from memory (not always good), but the exact pressure settings are not that important, just pointing out that you could set the pump down closer to the K-Plane settings or maybe even slightly lower. Keep in mind that these pumps were all originally designed for outboards and sterndrives, not tabs. The pump body markings are backwards from the line hookups. You have the higher pressure output port from the pump (UP) hooked to the line that pushes the cylinder out and the tab will go down.
Did you purchase these pumps new? I would think that a tab pump (or Bravo pump) would be cheaper.

Re: Trim Pump Pressure Relief Valve
 

Ok I am having the opposite problem that shawn is having. My tunnel tap keeps pushing back up. So can I increase the pressure on the check valves to stop this?

Re: Trim Pump Pressure Relief Valve
 

Shawn Who makes the rams and can you find the working pressure of them.

Re: Trim Pump Pressure Relief Valve
 

mmwalters no your problem would be leak down in some outher form.Maybe the thermal relief.Maybe shuttles.

Re: Trim Pump Pressure Relief Valve
 

Double check the line routing as I said in my previous post. The high pressure port is the "UP" port on the pump body (left side as you look at the pump). This should be hooked to the end of the cylinder towards the transom and should extend the cylinder. If that is correct, determine what your output pressure is. If it's in the 2000+ psi range, it may be a Bravo pump, which has a tough time getting to 3000psi because it's a faster rate pump (taller rotor) that has more rotor leakage and takes more hp to turn. If it's already a 3000+psi pump (competition style), you really can't push it much higher. And as FloridianSon said, you should find out what the max working pressure your rams are designed for.

Re: Trim Pump Pressure Relief Valve
 

Good point, I forgot he's not talking about pushing the tab down, it pushes up, I assume, without the pump running. When the pump is not turning, the locking/shuttle valves hold the pressure, not the standard relief pump pressure valves. Also there is a thermal/overload relief valve on the high pressure side that could leak.

Just a little over-zealous in responding the first time.

Re: Trim Pump Pressure Relief Valve
 

Ok I have tried 2 new bravo style pumps and one used HP pump with the same results. Has enough pressure to extend the tab but will not hold in position. The hoses are correct , when I reversed them the tab would not fully extend. I don't want to seem stupid but what are shuttles? I did reseal the cylinders and they looked ok.
Shawn sorry if you feel I hyjacked your thread but you still owe me a boat ride

Re: Trim Pump Pressure Relief Valve
 

system

Re: Trim Pump Pressure Relief Valve
 

#1 shuttle #4 thermal relief that is on the up side or the tab down.#3#4 pressure relief they make the pressure that the specs call for.

Re: Trim Pump Pressure Relief Valve
 

Am I right assuming the 4 is on the high pressure side? So If I increase the pressure on that spring my system will hold more pressure?

Re: Trim Pump Pressure Relief Valve
 

walters if you have tryed new pumpes then I would think you need a stronger spring on the thermal but I have never seen one offered.I think the problem is it is a single tab with a lot of pressure on it from the boat.Just my .02

Re: Trim Pump Pressure Relief Valve
 

Sorry we need to be in the chat room :drink: Yes I think if you increase the spring size it will take more pressure before it would let anything slip by.

Re: Trim Pump Pressure Relief Valve
 

After trying more than one pump, I would test/check the rams. What kind of rams are they? For a quick test of the o-rings, you could extend the cylinders completely, remove and cap the low pressure line at the rod end of the cylinder but leave the cylinder port open, then run the pump a bit more. Does more oil come out of the cylinder port? If so, it has to be leaking around the piston.

Re: Trim Pump Pressure Relief Valve
 

Ok I think I am understanding now .An increase in spring pressure on 1 and 4 will help my system hold more pressure. Is that correct?.
Thank you very much for all the help. I have been working with this problem for 2 years with no sucess.

Re: Trim Pump Pressure Relief Valve
 

They are Cylinders from Dana marine and my tab is big 42''x26''

Re: Trim Pump Pressure Relief Valve
 

I should add, make sure you run the pump in the proper direction. If you don't and you don't have strong cap on the removed line, you will get an oil bath!

Re: Trim Pump Pressure Relief Valve
 

mmwalters,

Check valve on the "up" side,
overpressure valve (#4),
or ram seals.

One of those will be letting your tab creep up.

The outboard/Bravo style pumps have an overpressure relief to allow the motor to kick up if you decide to drive it up the boat ramp at 30 or so.

Re: Trim Pump Pressure Relief Valve
 

Just # 4

Re: Trim Pump Pressure Relief Valve
 

Ok Thanks guys I will try that. How come we are all still awake?

Re: Trim Pump Pressure Relief Valve
 

The thermal pressure setting on the pumps that I have worked are all set at or above 4500psi. This should be high enough. If not, you could damage the pump going much higher. I believe the pump body can crack around the shuttle valve area at about 5500psi. If you have adjustable positions on the tab for the cylinder, as I have seen on Dana tabs, you could move the rod end out further on the tab to change the leverage point. Just pointing out ideas! Good luck!

Re: Trim Pump Pressure Relief Valve
 

If you look at the shuttle it would not matter if it was one hunderd pound on one mill gram spring the door is shut and no pressurs could open it.

Re: Trim Pump Pressure Relief Valve
 

Falcon your right it could.I know one thing that's one big tab and it will put a lot of pressurs on any system.

Re: Trim Pump Pressure Relief Valve
 

Just saw the tab picture. Those cylinders don't have much leverage on that tab and it doesn't look like moving the rod end out to a further hole is an answer, unless you have new longer piston rods made. What you really need is more piston diameter, but that doesn't look easy either because you don't have much room in the cylinder mounting location.
What I would do is determine the usable range of the tab. How high is high enough and what's the lowest you would like it. Then with the usable stroke range of the current cylinder body determine a good mounting point for a longer piston rod that will still raise the tab high enough. This will maximize your cylinder leverage on the tab with the current cylinder design. Of course, I wouldn't do this until it's determined that you don't have an internal cylinder leak as the real culprit.

Time to get some sleep!

Re: Trim Pump Pressure Relief Valve
 

Falcon I am thinking like you if he moves the point out further it should lessen the pressure.If he does not ever use the tab in the full down pisition there should be ram to meet his needs.

Re: Trim Pump Pressure Relief Valve
 

Shawn who makes your rams?

Re: Trim Pump Pressure Relief Valve
 

MMwalters before we try to blow up your pump I would like to try something else first.I am think outside of the box here and I need a day in the shop to play with my toys. :drink:

Re: Trim Pump Pressure Relief Valve
 

Hey guys, go home from work and all sorts of writing takes place, sorry I missed it until now.

Michael, hop in anytime, the beauty of this board is the free flow of knowledge and experience. I still owe you a ride and can't wait to pay up hope Sally can join us.

My tabs were made by Hynautic but I do not know the operating pressures. I bought them from someone on the board for under a grand complete, two tabs, two pumps four lines some fittings etc. I think it will be a pretty good deal when I get it running right.

I forgot these were made to work with the outdrives and are too strong for cylinders.

Unless I reset the pressure, I will have the same problems with the new and improved cylinders.

My set up is installed right, just too strong. Worked like a charm the first two times and see ya later after that. I plugged the blown cylinder and used the other to hold the tab in the up position until winter when I could fix it right.

Should I take this to a nydraulic shop to have tested and pressures set, or am I better off buying the gauge to set it up myself?


Thanks for all your help
Shawn

Re: Trim Pump Pressure Relief Valve
 

FloridanSon I am open to any idea. It is cold up here so I have not planned to blow anything up for a little while. Have been giving much thought to larger bore cylinders though. The bore on my cylinders is onlt 1 1/4''
Shawn see you leave work and things get done.

Re: Trim Pump Pressure Relief Valve
 

Need some help here.If someone would go to search type in trim pump on the fourth page half way down there is a thread that Magnum started and it is called K plane pump.Shawn I allso think you were the last one to post an answer on that thread,.but if someone could bring it up to this thread for me I will say a prayer for them.Shawn if your pump is like the one in the thread then we can get it real close to what you need 1800lb.just by backing off the jam nut and turning out the spring holder 3/4 of a turn.

Re: Trim Pump Pressure Relief Valve
 

http://www.offshoreonly.com/forums/s...ad.php?t=64498

Floridasun, you do have a pretty good memory, and yes Michael, I did set my alarm for midnight to see what you all were up to tonight and am somewhat disappointed.

I wish I had paid more attention to post #5.

If 3/4 of a turn changes the pressure from 3,600 to 1,900 it must be pretty sensitive.

How good is this pump compared to the drive pumps?

Thanks

Re: Trim Pump Pressure Relief Valve
 

Any of the newer pumps have the same motor. The pump sections vary in pressures settings and rate. Standard K-Plane pumps, Merc Racing outboard pumps, (the one you have) and the Competition pump have the same rate pump section. The Bravo pump is the only fast rate pump (taller pump gear section). The Merc Racing outboard pump and the Competition pump (used for the competion version tabs w/ss cylinders and the MC6) are the same except for the solenoids and mounting. I have been told that although the pump sections are the same design for the standard K-Plane pump and the comp/outboard pump, they have to hand pick them because some pumps can't make the high pressure ratings because of internal pump rotor leakage (this is not leakdown). So to make a long story short, the pumps (although mounting and solenoids vary) are of basically the same quality, no real differences. As far as sensitivity, don't worry about your exact pressure setting on those small tabs. It shouldn't take much pressure to operate them, 1000psi may be enough.
Two completely opposite problems in the same post!

Re: Trim Pump Pressure Relief Valve
 

Falcon so you are saying he has the trim pumps rated at 2600-600 not the sport k plane rated at 1900-800 or the competition at 3600-2000.The one in my post with the pic is a trim pump.Falcon also been trying to figure out MMwalters problem.Now I'm leaning toward ram leakage or the system has air.Being help is the worlds greatest thing but trying to figure out what is wrong with something without see it is the tough task.

Re: Trim Pump Pressure Relief Valve
 

Falcon, thanks. My tabs are mounted on a 17 x 40 x 5/8 aluminum plate that acts as a tunnel tab. Is 1,000 lbs of pressure enough to hold this down while running and also keep it up?

shawn

Re: Trim Pump Pressure Relief Valve
 

The area of the tab 17" X 40" is 680 SQ IN. The area of a 1 1/4" cyl is, oddly enough, 1.226"You have two of these cyls so your total area is 2.452 SQ IN. 2.452 SQ in X 3000 PSI = 7356 LBS of down force. 7356 divided by 680 SQ IN of tab area = 10.817 lbs of air PSI resistance. I would think that @ speed you could easily exceed this air PSI. I realize that the angle of attack of the cylinders will affect these #, but you have an enormous amount of area to overcome. I don't ever see them working as is. Have you talked to DANA about this?