Logo
FULL SITE MENU

Please Help - 1979 Wellcraft - Drive stuck in gear; won't shift back to neutral

T

tvoigt

New member
I have a 1979 Wellcraft Suncruiser 225, Alpha 1; PO claims he swapped motor to a GM 350 Crate engine. Runs great, shifts into gear just fine. The problem is it won't shift back into neutral from drive or reverse. So when I pull the lever back to idle, I have to shut the engine off, then shift into neutral and restart engine. But again, it shifts INTO forward or reverse just fine, it just won't shift back into neutral with the engine running. After doing some extensive research its obvious the first thing to check is the shift interrupt switch. I have the boat at a shop right now having a mechanic look at it but I'm getting nervous that he doesn't fully understand what the interrupt switch does. Earlier today he said, "most people just remove those on these older boats". And, "its not functioning properly anyway because I can start your boat while its in gear (forward)". He thinks its the clutch dog in the lower gear assembly that's causing the problem and thinks I should replace the whole drive. Also, when I looked for the interrupt switch, it was strangely placed upside down, underneath the plate that usually holds it. I thought this was strange as all the pictures I've seen its always mounted on top so its accessible.

Any thoughts? I appreciate your time and thanks in advance for your response.
 
take the boat out of there pronto, find another shop.
the start-in-gear protection is done at the control box. the shift interupter is mounted at he engine riser. It must ground out the ign momentarily to allow the gears to seperate.
 
Difference between a good mechanic and a hack...
Back some years ago, I reengined my boat by someone who claimed to be "an expert". When the drive kicked up every time I shifted to reverse he said, " Worn parts in the latch. You can't get those parts anymore (not true!). You'll have to buy a whole mid section to the drive ( a Volvo) ... Total cost $900. "

Well. Turned out there is a link in the drive that needs to be set for correct prop rotation ( LH vs RH). It was backwards, i.e. drive locked down in FWD, free to kick up in REV. Total cost to fix $0.35 ( A new cotter pin on the cable end). And about a half hour of my time.

Find a CERTIFIED MERCRUISER mechanic. Don't trust the sign on the building, that mechanic could be long gone.
 
If I understand your post correctly then here is what you have for an issue.

First, the shift interrupter switch is there to interrupt the ignition when shifting from gear to neutral. The exact problem you have when the switch is not working or out of adjustment.

The neutral start switch should be in the shift control box so when in gear you can not crank over the engine at all.


To test an interrupter switch, start engine, activate the switch and the engine should stall. If it does then the switch is working. if not check switch with an ohm meter and if good check wiring. one leg of switch goes to ground the other leg goes to negative side of coil.
If switch is defective try to replace. Very hard to find as it is no longer available.

If the switch is good then it is a cable adjustment. procedure will be in a service manual for that year boat/engine.

The neutral switch has two wires going from the control box and connects inline with the Crank wire to and from the ignition switch so if the motor is off and someone shifts the control into gear this opens the circuit so the engine will NOT turn over. (starting has nothing to do with it) Only cranking will/should NOT occur.
 
.................

tvoigt said:
I have a 1979 Wellcraft Suncruiser 225, Alpha 1; PO claims he swapped motor to a GM 350 Crate engine. Runs great, shifts into gear just fine. The problem is it won't shift back into neutral from drive or reverse. So when I pull the lever back to idle, I have to shut the engine off, then shift into neutral and restart engine. But again, it shifts INTO forward or reverse just fine, it just won't shift back into neutral with the engine running.

All Dog Clutch drives shift into gear just fine. As said in this thread, it's shifting from gear back into Neutral that is the problem.

Dog Clutch engagement teeth are cut at an incline, or are "ramped" so to speak. Not the actuall hypoid gear teeth..... the engagement teeth. ,
This type of cut is to ensure that both FWD and REV engagement continues to hold.

At slow speeds, and while the engine/drive spins the propeller, the Dog Clutch undergoes propeller thrust resistance.
This resistance is what wants to continue holding engagement..... as it should!

As eluded to, the SI (shift interrupt) system (via cable jacket resistance and lever arm movement), momentarily disrupts ignition, which in turn causes the engine RPM to stumble.
This occurs while simultaneously allowing the Dog Clutch to release.

All of this must work together, or you will have trouble such as what you describe.



I have the boat at a shop right now having a mechanic look at it but I'm getting nervous that he doesn't fully understand what the interrupt switch does.
Any.... I mean ANY Merc Mechanic should know full well how to trouble-shoot and adjust the Merc SI.
They should also know full well that the final adjustment must be made while the boat is in the water..... no exceptions.

Take your boat elsewhere before this guy costs you money in the form of damage.

Earlier today he said, "most people just remove those on these older boats".
Unless you are a HillBilly...... that is NOT TRUE!
Again.... take your boat to someone who knows how the SI works and why....., and who knows how to adjust it.
Click to expand...
 
Last edited:
Thanks for the advise everyone. I am going to pick up the boat as soon as they button it all back up.
Turns out my theory was correct, the Shift interrupt switch is not even installed. Looks like the PO removed it. Also, the boat is shifting into neutral out of water. I'm going to purchase a new shift plate assembly, Part 864363A1 Shift Interrupter Switch Plate Kit $120.00, and install that. Thanks again!
 
Last edited:
All Alpha mercruisers will shift out of gear when out of the water.

That is considered normal.

It is when they are in the water and they DONT shift out of gear that is not normal.


One note,

where was your missing shift interrupter switch mounted?

Any pictures?
 
Back
Top