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90Hp Johnson 1981 Power tilt trim not working

ed_in_va

New member
"Good to find this forum site

"Good to find this forum site and posters....

Question...My tilt trim unit is not working at all. It's on the bench and the motor runs in both directions, but cylinders do not move at all.

I've tightened the release valve and it seems to be tightly seated. I've filled the unit with ATF fluid to overfull...still no pumping action or cylinder movement at all.

Can someone suggest a method of troubleshooting this hydraulic unit? I have previously removed the check valves from the housing and they seem to function freely. Thanks Ed in Va."
 
"Thanks Greg..
I've ru


"Thanks Greg..
I've run the trim motor for quite sometime in both directions, no movement at all.

If air is in the system, shouldn't there have been some movement of the cylinders even with air, because the unit is on the bench and the cylinders have no load on them.

I can manually extend the large tilt cylinder by pulling on it with the trim/tilt motor running, but when I disconnect the power, I can retract the tilt cylinder by pushing on it by hand as it offers little resistance to the force.

The unit worked intermittantly for awhile before it stopping working completely. Seems like it would power down (but not up) if I remember right. It' been awhile since it has worked. Ed in Va."
 
"I'm out of my depth a bit

"I'm out of my depth a bit here, but I would think if testing on a bench, you would want it in the normal operating position to ensure that the pump primes."
 
"it sounds like ur unit,is ful

"it sounds like ur unit,is full,of air,..since u have on bench,...pull all caps,push trim rods all te way in,fill almost to threads...rel valve open,do same w/tilt cyl...then,run,ck,refill.i believe,i would rebuild those cyl pistons and end caps while off."
 
"Thanks jwbmarine..

I&#39


"Thanks jwbmarine..

I've run the unit in both directons with the quick release valve open and closed. In the down mode, I can get fluid resistance by closing the quick release valve, but not in the up mode.

I can pull the tilt cylinder out by hand and then retract it with the tilt motor running in the down mode, when the cylinder reaches the bottom of it's stroke the motor will try to stall as normal.

But when I try to reverse the motor to extend the tilt cylinder the motor only runs and runs.

Have you ever seen a flow diagram of the pump manifold. I'm trying to find out how to identify each of the check valves and ( shuttle valve ) looking for a possible short circuit in the flow path of this unit. Thanks Ed in Va."
 
"This 'syndrome' seems

"This 'syndrome' seems familiar.
Take off the electric motor and then the pump-unit on top.
Inside the pump-unit there are 2 small 'balls' that operates as valves. Inside #71 on below pic. If those balls gets stuck, it acts just like You describe.
282094.gif
"
 
Thanks Morton..

I have


Thanks Morton..

I have had the oil pump out and also apart looking for something wrong with it. The two small steel check balls were both loose and not stuck in anyway. You can also see them move when turning the pump cartridge upside down.

The two gears and two steel check balls are the only components in the oil pump...nothing else to go wrong in there like a seal or o-ring.

There are several check valves in the large manifold housing...and also I've read here about the shuttle valve which shifts oil from the trim cylinders to the tilt cylinder when the trim cylinders are completely extended.

I feel like something in the manifold is stuck or blocked but don't know how the manifold flow is routed to help locate the problem.

Ed in Va.
 
"It is a messy operation. I us

"It is a messy operation. I usually clamped the unit in a vise and ran the pump with a battery drill. Double check that oil is not going out of the holes with the balls, they are for in only. You may have to remove the plugs #60 and check that the valve #9 is moving freely. That is the one directing up and down."
 
"Thanks Morton, I'll find

"Thanks Morton, I'll find and check the shuttle valve tomorrow.
That's a good idea with the cordless drill.
I might be able to see little more by doing that.
Ed in Va."
 
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