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75 Formula Shift Issue

8

805HD

Regular Contributor
Shift interrupter switch not engaging...

Boat ran just fine first outing, shifted like butter all day.

Second time out shifting issues. Drive will go into gear but won't come out with engine load on it. Shut the engine off, back into neutral, restart, select gear, drops in fine but won't come out. On the trailer I noticed the notch that actuates the arm on the interupter switch barely moves when shifting. The plate with the notch moves freely by hand but barley moves when moving the shifter at the helm.

I adjusted the brass barrel out of curiosity, 10 turns out got the notched plate to move enough to engage the switch but it stayed engaged and only for reverse which I know isn't right. Its just interesting because the boat was shifting fine a week ago and Ive done nothing to it since!

The shifter isn't soft or spongy.
Shift cable is dead on at 5 7/8'' barrel to stud.
Idle set around 600rpm.

Any ideas?
 
805HD said:
Shift interrupter switch not engaging...

Boat ran just fine first outing, shifted like butter all day.

Second time out shifting issues. Drive will go into gear but won't come out with engine load on it. Shut the engine off, back into neutral, restart, select gear, drops in fine but won't come out. On the trailer I noticed the notch that actuates the arm on the interupter switch barely moves when shifting. The plate with the notch moves freely by hand but barley moves when moving the shifter at the helm.

I adjusted the brass barrel out of curiosity, 10 turns out got the notched plate to move enough to engage the switch but it stayed engaged and only for reverse which I know isn't right. Its just interesting because the boat was shifting fine a week ago and Ive done nothing to it since!

The shifter isn't soft or spongy.
Shift cable is dead on at 5 7/8'' barrel to stud.
Idle set around 600rpm.

Any ideas?
Click to expand...

1. On a trailer the interupter may not engage as there is no load on the prop and prop shaft. it has to be confirmed in the water under load

2. if you activate the switch only ( anytime on or off trailer) does the engine stall?
 
kghost said:
1. On a trailer the interupter may not engage as there is no load on the prop and prop shaft. it has to be confirmed in the water under load

2. if you activate the switch only ( anytime on or off trailer) does the engine stall?
Click to expand...
Well damn, thought I found the problem. So without load on the prop even the mechanical mechanism that activates the switch doesn’t work? I’ll get it fired today on the trailer and see if the switch still functions. I just find it hard to believe the switch went out just sitting in the trailer, but crazier things have happened.

Also, glad to see you’re still on here buddy! It’s been a minute!
 
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Yes, its no more than an on/off micro switch. When depressed it shorts Coil - to ground which kills ignition. (When working properly you barely notice this happening.)

With ignition OFF

set meter to ohms. Connect either meter lead to one wire with one lead coming off switch. There typically is a small terminal block where the wires are connect from the swith and engine wire harness

Meter should read a direct short when Switch is depressed (like checking a good fuse Zero ohms) and open (like a blown fuse) when not depressed.

If it does not show short when depressed the switch is bad.
 
kghost said:
Yes, its no more than an on/off micro switch. When depressed it shorts Coil - to ground which kills ignition. (When working properly you barely notice this happening.)

With ignition OFF

set meter to ohms. Connect either meter lead to one wire with one lead coming off switch. There typically is a small terminal block where the wires are connect from the swith and engine wire harness

Meter should read a direct short when Switch is depressed (like checking a good fuse Zero ohms) and open (like a blown fuse) when not depressed.

If it does not show short when depressed the switch is bad.
Click to expand...
I checked the switch, it’s good. I also verified continuity from the switch lead to the coil. Meter beeped from both positive and negative posts of the coil to the switch when the arm with the wheel was depressed…

Was kinda hoping it would have been as simple as just a bad switch..
 
You say all was good one day & goofy next time with absolutely nothing done to the cables. Yes/No?

You also mention 5 7/8". ***This is important, read carefully.***
Early units use 5 7/8" I'm not sure of the exact cut over date but is about where you are at. Later units use 6".
The difference is a long or short slot in the arm for the lower cable stud to mount. Long is about 2" (uses 5 7/8") & short is about 1" (uses 6"). THIS ADJUSTMENT IS CENTER OF BARREL TO CENTER OF STUD.

As cables wear you slowly gain clearance between the moving cable & stationary housing. This creates lost travel action at each bend. You may just have worn cables (controller to shift plate & plate to lower unit).

How old is lower cable? Does it move smoothly & easily?
 
Droid said:
You say all was good one day & goofy next time with absolutely nothing done to the cables. Yes/No?

You also mention 5 7/8". ***This is important, read carefully.***
Early units use 5 7/8" I'm not sure of the exact cut over date but is about where you are at. Later units use 6".
The difference is a long or short slot in the arm for the lower cable stud to mount. Long is about 2" (uses 5 7/8") & short is about 1" (uses 6"). THIS ADJUSTMENT IS CENTER OF BARREL TO CENTER OF STUD.

As cables wear you slowly gain clearance between the moving cable & stationary housing. This creates lost travel action at each bend. You may just have worn cables (controller to shift plate & plate to lower unit).

How old is lower cable? Does it move smoothly & easily?
Click to expand...
Correct, last weekend it was fine sat on the trailer for a week and now it’s goofy. The lower shift cable was just replaced so last weekend was its first time out since replacement. The controls and cables are smooth. No springy, bunchy, dragging resistance at all.

The cable that was put in the boat is,

“Sierra Marine 18-2190 Mercruiser Lower Shift Cable”.

The boat is a 1975. She’s old, things wear/ settle, I understand tolerances vary. When I did the cable I didn’t do an adjustment. I just installed, verified F, N,R and sent it. Perhaps a shift adjustment from scratch is what she needs.

When you take that measurement, whether it’s 5”7/8 or 6” are you measuring with the cable installed on the shift plate or off?
 
shift cable adjustment.

Remove both from bracket.
Shift control to full wide open throttle.
Now push short cable all tbe way in by hand and turn prop C'clockwise to engage clutch dog. Maintain slight positive pressure on ahort cable end and make measuremint from barrel to center of mounting hole in cable end.

Mount short cable to bracket.

Now see how control cable fits. Adjust barrel to fit. Now readjust barrel 3-4 turns towards cable (not cable end).

Not mount control cable.

Now manualy, Engine NOT running.

Bring shift control to neutral. Make sure prop spins freely and no clacking.
Move shift control to forward detent and confirm at prop positive engagemnet. Repeat for reverse.

Who did cable install? How much slack at cable end where set screw is in F shaped part?

How far did you threaded part of shift cable thread into bellhousing? Should be maybe 1-2 threads showing only
 
kghost said:
shift cable adjustment.

Remove both from bracket.
Shift control to full wide open throttle.
Now push short cable all tbe way in by hand and turn prop C'clockwise to engage clutch dog. Maintain slight positive pressure on ahort cable end and make measuremint from barrel to center of mounting hole in cable end.

Mount short cable to bracket.

Now see how control cable fits. Adjust barrel to fit. Now readjust barrel 3-4 turns towards cable (not cable end).

Not mount control cable.

Now manualy, Engine NOT running.

Bring shift control to neutral. Make sure prop spins freely and no clacking.
Move shift control to forward detent and confirm at prop positive engagemnet. Repeat for reverse.

Who did cable install? How much slack at cable end where set screw is in F shaped part?

How far did you threaded part of shift cable thread into bellhousing? Should be maybe 1-2 threads showing only
Click to expand...
I did the install, I apologize but you lost me on the F shaped part. Could you please clarify?

I’m by no means a marine mechanic but I followed a good video on YouTube, a 6 part removal, build and install from an actual Mercruiser mechanic. Not just some guy in his garage. Definitely didn’t make any assumptions or leave anything loose. Did it by the book.

The boat still shifts fine minus the disengagement once in gear. Engine off it shifts fine. The switch is good so something moved or stretched.

As I said before I didn’t do an adjustment because I had smooth movement with positive lock and ratchet on forward and reverse and free spin on neutral. Nothing looks loose. I’m gonna investigate deeper today and I’ll repot back.

Really appreciate the help!
 
805HD said:
I did the install, I apologize but you lost me on the F shaped part. Could you please clarify?

I’m by no means a marine mechanic but I followed a good video on YouTube, a 6 part removal, build and install from an actual Mercruiser mechanic. Not just some guy in his garage. Definitely didn’t make any assumptions or leave anything loose. Did it by the book.

As I said before I didn’t do an adjustment because I had smooth movement with positive lock and ratchet on forward and reverse and free spin on neutral. Nothing looks loose. I’m gonna investigate deeper today and I’ll repot back

Really appreciate the help!
Click to expand...
Send me your phone number

Where are you located? If outside US you will have to call me
 
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