Tilt Troubles, Need advice

Was out on a lake fishing over the weekend and while running down the lake I took the old boat up close to WOT for about a mile run. It was then that my son and I both heard a strange noise, like something had flown out of the boat or hit something. I lowered speed and we continued on our way trying to pay attention to any thing that may seem out of norm but all seemed well. When I tried to load the boat on the trailer I noticed that when I tilt the engine up a bit like I always do and apply throttle the tilt will just not hold it and it will slap back down. The noise is the same slap I heard while running. Does this sound like something some of you have heard of before? I have done nothing yet as far as trying to trouble shoot the issue. The tilt works fine while lifting the motor on shore. The tilt has always slowly leaked down since I have had the boat, never thought too much of it.
It is a Johnson 150HP J150STLCOS or H the last didgit is torn off so I am not sure if S or H and do not know the difference between the two.

Any advice as to which direction I should take would be great.

Thanks
Will

Re: Tilt Troubles, Need advice

First thing to do is to check the PTT fluid level. Have the engine in the extreme tilted up position and lock it there. Remove the fill cap screw and O ring seal from the reservoir. Fill the reservoir to overflowing, then re-install the fill cap and O ring seal. Release the tilt lock lever and run the unit up a down a couple times to bleed out the air if it exists (self bleeding) You may need to repeat this process if the unit was low on fluid.

The last digit on the model number of J150STLCOS, whether it's a "S" or a "H" is not important as the last number/letter is simply a factory run number of no consequence. Uour model number indicate you have a 1985 150hp Long Shaft Johnson outboard.

Re: Tilt Troubles, Need advice

Joe, thanks for the quick reply.
I did as you said, but it only was low maybe 1 oz of fluid. I have ran it full up/full down 6 times and the level is still full. When in about mid tilt position, and expect it to hold there it is definently going down. I see no real oil leaks anywhere. I opened the valve on the side (going through the motor mount on starbord side) 1 turn and it bleads down fast. close it tight and cycle up/down seems the same. Fluid is still good.
Guess I may have blown the tilt cylinder packing? Just a guess.

Re: Tilt Troubles, Need advice

Next question, would a rebuild be a good dyi or is it something complicated? I consider myself handy with tools. Is a manual a must have?
Thanks for the help.

Re: Tilt Troubles, Need advice

There's no packing in there... only check valves and quite a few of them. A manual is a must if you're going to tear into one of those units.

Re: Tilt Troubles, Need advice

Ok, I was thinking maybe the piston seal or something like that. I will order a manual and go from there.
Thanks Joe.

Re: Tilt Troubles, Need advice

Wover98 said:

Ok, I was thinking maybe the piston seal or something like that. I will order a manual and go from there.
Thanks Joe.

Click to expand...

That could be the case my friend... like I said, there are many areas that can cause that. Here's a diagram of points that would have pressure applied to when in the fully tilted up position (Trim Tilt Out)... the position whereas it should just sit there and not drop down.

In my experience, although there are quite a few areas is which a slow leak down is caused, 9 times out of 10 it is caused by a failure of one of the valves located directly under the reservoir... either the aluminum rubber tipped valve or the O rings on the brass valve assembly next to it. Picture the diagram below in the fully tilted position whereas the red portion would be the fluid with the weight of the engine pushing down on it.

Re: Tilt Troubles, Need advice

Ok, that helps a bit. When I was focusing on the seals in the tilt cylinder I was thinking of how it would tilt up then slam back down when I applied throttle to load on the trailer. BUT I see from your diaghram that it could be several different check valves. Like that impact valve, or the expansion relief valve or even the manual release valve would release pressure if it were to go bad. What ever it is it seems to have happend suddenly. Although it has always had that nagging slow leak. I think I should order that manual. Do you have a suggestion as to which to buy? Seems to be several on the market.
Thanks again Joe, your a life saver.

Re: Tilt Troubles, Need advice

I prefer the factory manual that is specifically for the one engine in question. The other manuals that take in more than one engine can be quite confusing. They cost a few dollars more but in my humble opinion... very well worth the difference.