Taking apart valve body on tilt trim 1988 40hp

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sparky15

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I have a 88 evinrude 40hp E40TTLCCS and been battling with the t n t for a while now, I put new o-rings in the tilt and trim cylinders and installed a new tilt motor.

It will lower fine but when it comes to raising it, I have to help it up, it stays up on its own.

I'm at the valve body thinking that has to keep it from raising on its own. I have the valve body apart and would like to replace o-rings, etc. I pulled the "rubber slugs" off, one being right next to the manual release screw having a snap ring holding the internal parts of the assy in...... how do I get to those internal parts??? snap rings are off and it doesn't want to budge.

I do have a service manual which shows how It works but nothing about getting in to the valve body

Thanks in advance!
 
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RRitt

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Re: Taking apart valve body on tilt trim 1988 40hp

need some pics
 
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RRitt

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Re: Taking apart valve body on tilt trim 1988 40hp

you have to assemble the valve body and run it inside of a bucket or plastic bag. The pressure will blow out the check valves. Usually the pressure is enough to send the plug flying 10-15ft. but i have had them smack the side of bucket hard enough that they would have ricocheted off the fall wall of shop. if it does not drift down then it is more likely a problem with your rams or plumbing than valve body. if pressure regulator was set too low then it would not have enough pressure to hold. If MRV was going bad then it would bleed down. If check valve was going bod then it would also bleed down. Since it stays up then regulator, check valve, and mrv would seem okay. that leaves plumbing and cylinders.
 
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sparky15

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Re: Taking apart valve body on tilt trim 1988 40hp

Thanks for the reply Rritt
.
I put new orings in both cylinders and sprayed lines with brake cleaner.
Once I run the tnt and help the motor raise it will hold, and when lowered it seems to lower fine quickly until the last little bit then slows which I assume is the trim part.

If there was a leak in the plumbing or cylinders wouldn't it leak down? I plugged the sending unit hole on the trim cylinder with a short bolt and oring and when I plug the holes on the trim cylinder and pull on the ram there doesn't seem to be any pressure is this normal?
 
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RRitt

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Re: Taking apart valve body on tilt trim 1988 40hp

the trim cylinder has a telescopic piston shaft. it only pushes during trim cycle. during tilt it just flops about.

plumbing is usually a case of wrong hose connected to wrong port or a plugged line. some systems have three or four lines. systems with two lines are hard to mess up.
 
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sparky15

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Re: Taking apart valve body on tilt trim 1988 40hp

I'm just lost as to what I should look at next, that's why I was going to get into the valve body. Any suggestions on what to look at in the cylinders when I open them up, that might be keeping it from lifting on is own?

Thanks
 
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RRitt

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Re: Taking apart valve body on tilt trim 1988 40hp

you need to put valve body back together and assemble system onto engine. Plug the line going between tilt and trim rams for testing. Your system will be a single cylinder with one oil tube for "up" and another for down. Your system should lift and stay to any position. It will not handle more than 20-30 HP since it only has one ram but it should function perfectly on the trailer.

this configuration will give you known state and it should be fairly easy to isolate problem between motor, vb, and/or ram. During testing, isolate the trim system from boat wiring. Get a car battery and run the trim motor directly from battery. Black is ground. blue is up. green is down. blue and green must never be connected at same time, not even to ground.
 
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sparky15

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Re: Taking apart valve body on tilt trim 1988 40hp

I hope to get everything back together within the next couple of days.

Quick question, after looking over the manual again, I feel like I didn't see a part that the manual lists as inside the tilt cylinder threaded to the inside bottom of the cylinder. They call it a stem valve release rod and listed as a relief valve assy. in a online parts diagram. Not cheap, $170. Would this have anything to do with my issue?
 
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RRitt

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Re: Taking apart valve body on tilt trim 1988 40hp

i don't know. omc loved to get cute with their hydraulics. rarely worked out for the better. I don't remember the internal construction of this particular system and how the piston interacted with the bypass. do as above with a single ram as see if you can lift and hold. holding is more difficult than lifting. Your prestolite design pump is one of the most time proven ever. It may have problems reversing direction if you over-exert the lift button. It is otherwise devoid of quirky behaviors. If you can lift & hold over night then both pump and cylinder are probably good to go.
 
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sparky15

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Re: Taking apart valve body on tilt trim 1988 40hp

Put the valve body back together and got it ready to run on the tilt cylinder alone, but motor wouldn't run unless I losened the valve body a bit. So ill tear it down and see whats going on.
 
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RRitt

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Re: Taking apart valve body on tilt trim 1988 40hp

sparky15 said:
Put the valve body back together and got it ready to run on the tilt cylinder alone, but motor wouldn't run unless I losened the valve body a bit. So ill tear it down and see whats going on.
Click to expand...


armature not seated into gears. line up before putting vb onto reservoir. spin slightly until everything falls into place.
 
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RRitt

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Re: Taking apart valve body on tilt trim 1988 40hp

it is self bleeding. as it cycles the air bubbles go back into reservoir and float to surface. if it works perfectly with a single ram then add the second. If it bleeds down or leaks, then it will be easier to identify source of problem.
 
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sparky15

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Re: Taking apart valve body on tilt trim 1988 40hp

I had it hooked up single ram and raised overnight and no leak down. Its hooked up with both cylinders now and sat overnight raised with no leak down. I also have it ran straight off the battery with 12ga wires.
 
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RRitt

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Re: Taking apart valve body on tilt trim 1988 40hp

so ... it's working?
 
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sparky15

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Re: Taking apart valve body on tilt trim 1988 40hp

No, stilI have the same issue, have to help it up on the up cycle
 
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RRitt

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Re: Taking apart valve body on tilt trim 1988 40hp

ok,
you have to help it up but once there it will stay at any angle for at least a few hours. We have known good plumbing and cylinder function.

the first suspect is your mechanical hinges. while the system was apart did you lift and lower by hand to make sure that the mechanical hinge function was not seized or binding?

once that checks out then your valve body isn't putting out enough forward pressure. This is most likely caused by a weak trim motor, weak battery, or corroded connection. If you lose more than 1V in the wiring or internal windings then the motor does not have enough torque to lift. If the motor and wiring is known good then it is the valve body. I do not believe repairing a valve body that holds but does not lift is within the capability of DIY repairs. It requires 2500-5000psi pressure gauges and an assortment of springs and shims. However, I doubt that it is a valve body since it is probably the original parts.
 
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sparky15

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Re: Taking apart valve body on tilt trim 1988 40hp

I manually lifted the motor for a season or two, its definitely heavy but no binding. The tilt motor I just replaced new arco. I can check the batterys voltage but its a newer battery and always plugged in and on a trickle charger. So rebuilding a valve body shouldn't be attempted? Who rebuilds valve bodies and what's the average cost$?
 
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