Lost Forward

[Twainer]

Took the boat out one last time to try & run most of the fuel out of it. Was cruising along at about 3,000 rpm when it revved up like I lost the prop. I immediately thought this is what happened & pulled the throttle back. Put it in gear again & sure enough nothing. Put it in reverse for giggles & it went into gear & moved. So obviously not the prop. What kind of issue might I be looking at?
Boat is a 1977 Mark Twain OMC with a 351W

 

[Redrig]

Test for 12v when in forward at the forward shift wire . If you are getting 12v then it's time to tear into the lower . It's either the shift magnet or the shift spring ( exact thing happened to me that you described and it was my shift spring , tab on the end broke off)

 

[southkogs]

... and be sure the stupid wire didn't just disconnect in front of the intermediate. Not that I've ever had that happen ...

 

[Twainer]

Test for 12v when in forward at the forward shift wire . If you are getting 12v then it's time to tear into the lower . It's either the shift magnet or the shift spring ( exact thing happened to me that you described and it was my shift spring , tab on the end broke off)

I am mechanically inclined but boats are new to me... where am I testing 12v up at the shifter or aft of the boat? If I have to tear into the lower (which will not be til winter) how much of a job is that? Are we talking comparable to an auto transmission with 100's of parts & special tools?

 

[Redrig]

The voltage test is done in the engine bay area . Kinda by your tilt motor you will have a thick black cable follow that and there will be two splice points where you can access the wires , green or forward and blue reverse . Test those To make sure your controller is sending out 12v in forward

 

[Twainer]

The voltage test is done in the engine bay area . Kinda by your tilt motor you will have a thick black cable follow that and there will be two splice points where you can access the wires , green or forward and blue reverse . Test those To make sure your controller is sending out 12v in forward

Great thanks

 

[kenny nunez]

The ohm reading to the shifting coils is 4.5-6.5 on low scale. Be sure that there is a stainless ground strap from a bolt on the side pivot cover to one of the bolts that attach the steering bumper. A momentary loss of either a ground or positive feed will snap either the spring or shear off a shaft. When testing with the ohm meter shake the wires going into the drive. Any time the drive has to be repaired the shift cable will have to be replaced . If there is a break any place on the cable do not try to repair it. Galvanic action will burn right through it and you get to repair the drive again.

 

[Twainer]

Test for 12v when in forward at the forward shift wire . If you are getting 12v then it's time to tear into the lower . It's either the shift magnet or the shift spring ( exact thing happened to me that you described and it was my shift spring , tab on the end broke off)

Ok... well I am just now getting around to looking into this. I was hoping the lug at the splice point was loose. Unfortunately not! Unplugged it there & was getting the 12V there in both forward & reverse.
I am mechanically inclined but never tore into anything like this. How much of a job is it? Are there any special tools needed? To be honest if I could gotten around to this before our cold weather I would have handed this torch over to the marine repair shop. I am fairly confident he is so busy I wouldn't see my boat before the 4th of July.

 

[Redrig]

just buy a good used lower unit , swap it over and go boating .

there are a few special tools needed to replace that forward spring and they can be tough to find.

If you decide to try to replace the spring PM me , I have alot of the stuff that you will need .

 

[southkogs]

I agree ... look for a new lower, and swap. It's a lot easier, and possibly even a little cheaper.

 

[Twainer]

just buy a good used lower unit , swap it over and go boating .

there are a few special tools needed to replace that forward spring and they can be tough to find.

If you decide to try to replace the spring PM me , I have alot of the stuff that you will need .

Yeah the more I look at it in the shop manual the more I believe I don't want to tackle this right now. Where are good places to start looking for lower ends on a boat this old?

 

[Twainer]

I agree ... look for a new lower, and swap. It's a lot easier, and possibly even a little cheaper.

Thanks for your input all.

 

[Redrig]

Where are good places to start looking for lower ends on a boat this old?

My replacement and current lower unit , I picked up from Ebay .

I got lucky and found a good seller , he sent me pics of the OHMs of the magnets and pressure tested it for me. got about probably 50 or so hours on it with no problems , check there and your local classifieds , shouldn't be a problem hunting down a decent one .

its pretty easy to swap it in too , get a new water pump kit and grease all of your splines

 

[southkogs]

I found mine through Craigslist. Like REDRIG, I found a good seller who knew what he was doing.

 

[Twainer]

Thanks guys... I will be on the hunt!

 

[kenny nunez]

If you get a good lower be very careful installing the shift wire. Since it is close to the lift gear do not move the drive until the wire is pulled through the intermediate housing. I have seen where the wire got damaged from the owner using the tilt before installing the wire.