Merc '71 Model 1350 Trim/Tilt Help Needed

[gidds]

I have is a list if issues to resolve, but this is No. 1......any help would be appreciated. I am looking for a Service Manual and a Parts List now but i'm hoping that I can get quick answers in the mean time. I purchased a CD containing a PDF version of a manual but it lacks the detail of something like a SOLEC manual.....anyway.....

Being the idiot that I am, I left the coast headed home this weekend without disconnecting the battery, seat shifted and the down button was pressed for an undetermined time. Got home and trim motor seems to operate but would not trim up or down. Semi-dry ATF fluid splattered on transom for forensic evidence of my stupidity. I opened up the hex screw at the top and bottom of each cylinder and ran fluid out as mush as I could figuring I would refill and check or at least prepare to disassemble. Filled up again but it did not work.

I guess i have three main questions.......

1) The only trim oil piston seal I have found is part number 18-2048 (on iboats). It is not listed for the 1350 but listed as a replacement for other high HP motors during that time period, so I'm hoping it would work for the 1350. I was going to replace both sides at the same time. Am I headed in the right direction and is it as simple as finding a pin / spanner wrench, disconnect bottom of cylinder, and install the 18-2048 ring on each side then reassemble? Any ideas if the 18-2048 is not correct?

2) How can I bleed or drain my whole system and put fresh ATF in, correctly fill, bleed and see if I have trashed the motor? Can I test the motor itself? It sounds as if it pumps correctly when the up and down arrow is pressed.

3) Previous owner installed a hydrofoil on the cavitation plate. One of the bolts / washers looks as if it locks the fin on the bottom of the cavitation plate to where it would not move (I don't know if it needs to move- I think this fin is a trim anode from what I have been able to read). I only have an up / down button. The manual/pdf that I have shows a remote control with a up/in&out/down buttons. What does the fin / anode do and do I have the correct trim / tilt control. The control I have is the aftermarket up/down button that is mounted to the throttle?

I am a novice.....I apologize. I have read numerous posts but cannot find good answers to my questions.....thanks again in advance...

BG

 

[Chris1956]

Re: Merc '71 Model 1350 Trim/Tilt Help Needed

BG - I am a bit concerned that you may not have the original equipment PTT setup. I will give you advice for the originan PTT unit, however.

1) the Oring that seals the cylinder base is either 3/4 or 1" in Diameter. If your rods are 3/4" then a Oring from the driveshaft on a Mercruiser Alpha 1 (avail from Mercruiser) (and some inline 4/6 Mercury Outboards) will fit it. You can also buy a complete cylinder rebuild kit for $40-50 ea.

2) First of all, you can use ATF, but the original fluid was 5W-30 motor oil. Fill the resevoir thru the aluminum slotted screw (top right of the resevoir).

To beed the cylinders (pump is self bleeding), you need to open the bleed screw on top of the cylinder (SS phillips machine screw) and run the pump in the down direction. Oil should spew out. When all the air is gone (no bubbles) install the screw with the o-ring, and bleed the other side. Now remove the cylinders and face the place where the lines connect up. Remove the up bleed screw and run the pump in the up direction. Whe no more bubbles, replace screw and repeat on other cylinder. Now run the tilt up and down a couple of times and refill the resevoir.

3) Zinc fin is adjustable using a 3/8 drive 1/2" socket on an extension. Put it thru hole above zinc and loosen.

 

[gidds]

Re: Merc '71 Model 1350 Trim/Tilt Help Needed

Thanks Chris.....but to clarify my questions based on your response.....

1) Do you know where I can get a cylinder rebuild kit from (the one you mentioned for 45-50 bucks)......

2) I think I understand with the exception of getting to the point where I open the cylinder to change the seal. Dont I need to drain the cylinders prior to opening? I am assuming that I disconnect the shafts at the bottom (where they attach to the engine as opposed to removing the top of the cylinder from the engine mounting plate.....

3) I shold have been more clear. One of the hydrofoil bolt / washer is compressing the "zinc fin" and looks as if it would be enough to keep the fin from moving (if it is even supposed to). What is the purpose of this zinc fin?

Thanks again in advance.....

BG

 

[Chris1956]

Re: Merc '71 Model 1350 Trim/Tilt Help Needed

A trim cylinder rebuild kit is available form www.dougrussell.com, and maybe some other places. I just guessed on the price. You need a special tool to install the teflon piston seal. The balance of the parts are o-rings.

The trim cylinders have a removable threaded plug that screws in from the bottom. The cylinder will drain when you open it. You can build a spanner from a boat deck key or fabricate one on your own. I used two six inch lengths of angle iron. I drilled a hole on each end of the angle iron pieces and bolted one end together. The other end got a bolt that just fits the holes in the cylinder plug.

 

[gidds]

Re: Merc '71 Model 1350 Trim/Tilt Help Needed

Chris (or anyone),

What is the purpose / function of the "tin fin" on the bottom of the cavitation plate......

Thanks

BG

 

[Scaaty]

Re: Merc '71 Model 1350 Trim/Tilt Help Needed

Chris (or anyone),

What is the purpose / function of the "tin fin" on the bottom of the cavitation plate......

Thanks

BG

Its an adjustable fin (bolt under rubber cover above it) to offset torque steer at the helm (wheel). If the boat want to go to the right when you let go of the wheel, turn the fin in small increments to the right. Left, other way.