Reverse Lock

[Rapanui47]

Sorry to pick up this old tread,but it heat home with me.
My 50 HP Mercury Outboard circa 1983, has separate Prestolite 105921 PTT pump unit installed inside the boat.
Speaking of this black knob you suppose to turn CW to disengage reverse lock or CCW to engage it. Mine just simply screwed onto some treaded post and do not rotate anything. So by turning it CCW I can completely unscrew it from this post. This post is the part of 1/2 inch nut like head, screwed into the nod of control block. When taken of inside is some sort of piston, which can be pushed by hand, but as far as I can see rotation of the know hason effect on this internal.
Am I missing something?
Can somebody she'd the light, please.

 

[merc850]

Why are you taking the reverse lock apart? The knob pushes on a plate that regulates the tilt up, the system has to be pressurized for this to work; the large nut has to be tight to allow the knob only to move in and out.

 

[Rapanui47]

Thank you Merc850 for picking it up. Everything you say makes cense. The only reason I started investigation and disassembly because my knob can be completely unscrewed. I guess this post I am referring to had a flat head bolt inside the big nut and suppose to rotate with the knob and press on this piston inside? Mine does not. System is charged with oil and pressurized. Motor is going up and down. I simply do not know if it is in engaged or disengaged position now. how to check? Do you recommend to disassemble it again and try to rotate screw head inside the big nut like head?
Appreciate your time and expertise.
Val

 

[merc850]

Can you post a picture of this pump? The large nut should be tightened into the case and to operate the unit the small knob should be set by turning to the left until it stops.

 

[Rapanui47]

Thanks Merc850.​

My PTT unit is exactly as you show in your picture and extract from operating manual.​

I do not want to disassemble it again, but confirm that inside large nut assembly looks like on your picture which shows O-ring and moving plate. The only difference I can unscrew control knob completely of. See the picture. One local expert told me that it broke of the post but I do not see any welds or any break lines. I am in Lake Havasu, so hope to find answer locally, but would appreciate if you can post remaining pages of this PTT operating manual.​

Thanks for all your help and support. Happy Thanksgiving to you and yours.​

Valeri​

 

[merc850]

It looks like the knob was turned too far and unscrewed from the internal bolt; remove the assembly - turn the large bolt until it bottoms out in the nut and hold it while you screw the knob tightly on to the threads. You could use Loctite to help hold it.

 

[Rapanui47]

Thanks.
Would you please post remaining pages of this manual related to PTT.

 

[merc850]

The only other pages concern mounting and bleeding.

 

[Rapanui47]

Thank you