74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

[r6speed]

Hi,
I am new to owning a boat however I have owned, raced, and worked on a lot of vehicles in the past so I consider myself "handie".

I bought this boat and of course nothing but problems first starter, then electric trim motor, then relays and wiring, then fuel pump, ect ect.
After everything I went through the boat has been running great and everything works great EXCEPT for this problem it started cutting out like slipping like hitting a brick wall for just a split second and at totally random times, it quickly went from just every so often to constant slipping or cutting out.
From my little learning I have had on boats it looks like it has something to do with my shift linkage, the part that cuts out when the boat gets put into gear (goes into gear fine though) but when its slipping I can see a little electric node type deal clicking and the shift linkage jolting really bad...not sure if it is that or not. I checked all the fluids and they all look alright and at good levels. I have been reading on here about this problem and have found none where people actually figure out the problem and POST THE RESULT.
I know it could be the dog gear but I would like to be sure before attempting to tear this completely apart.
Any advice would be appriciated!!


EDIT: I took the prop off to check if the rubber hub was slipping but how do I check that? Its not moving by hand but thats not much force...

EDIT#2: I don't think its the rubber piece cause if it where it should just stall out not JOLT fiercely

 

[Lyndy]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

The year outdrive you are mentioning does not have a shift linkage or dog gear. Up though 1977 were electric shift. There should be an electrical cord coming out the back of the Intermediate Gear Case and into the outdrive. Given your description, I would check for a faulty electrical connection. If you can post a picture of your outdrive it would help both me and others to figure what you have and some extra items to check out. In addition other things you are describing there are other problems that may exist. The picture of your outdrive will help narrow down the possibilities.

 

[r6speed]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Ok, the outdrive is also an omc250 and I do have a book for it. According to the book it has whats called a "pinion gear" which to me looks like a dog gear, as for the shift linkage I am refering to the cable part in the engine bay that you adjust for going into and out of gear...the part that stalls the boat for easy engage of the gear. That has a electric piece on it with a little node and that whole assembly JOLTS when it does its thing
but hey just like I said I know nothing about this.

I will get some pictures and get them on here within the hour, thank you for your help!! Its greatly appriciated

 

[r6speed]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Sorry about the picture quality I was unable to find my camera so I had to use my cell. Let me know if there is anything else I can take pics of that will help. Thanks

 

[Lyndy]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

At least I know why things were not adding up. Your drive is at least 1978 or newer. It is either Model 400 (4 Cylinder) or 800 (V6/V8). Think it may be the shifting mechanism but this one I am not familiar with but there are plenty on this forum that are. When they see the pictures I suspect you may get your answer(s).

 

[r6speed]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Ok thanks for the information, so the outdrive must of been replaced and its a V8 ford 302 engine if that helps anything. I sure hope its my shift linkage I really have a deep suspision its that little electrical guy but I just don't even know if that could be it or what that is??

Thanks!

 

[NW Redneck]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

As lindy said, your drive is a '78 or newer. Before that shifting was done by electro-magnets in the lower unit and didn't have the parts you show. That looks like a shift interupter that cuts out the motor for a split second to relieve strain on the gears while shifting. If it is faulty it could be your problem. If your motor is a ford 302 (like mine) it is either a 175hp or 190hp.
I don't think the 302 was ever rated for 250hp. I could be mistaken though. The ford 351 was 235hp. The drive should be an 800 series for use with a v8.

 

[r6speed]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Like I said in my first post I do think it could be something to do with that interupter but I'm not sure...does it look ok? What could go wrong with it? where do I start? what is that little electronic thing I have circled in the picture? Thanks

 

[r6speed]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Here is a pic of the outdrive tag maybe that will help

 

[WizeOne]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Here is a pic of the outdrive tag maybe that will help

Your drive in a 1981-1985 full mechanical shift 800. With the proper accessories it could have well been mated to the original electric shift intermediate housing OR the whole ball of wax could have been grafted into your boat.

I won't pretend to know what is the cause of your issue beyond the fact that your shift converter, at minimum, needs to be calibrated with the shift cable coming back from your throttle/shift lever.

Get a manual for the 1981-85 full mechanical shift drive, not the 1978-80 hydro-mechanical drive.

btw, you have the latest iteration of the stringer drives. Set it up right, maintain it and you will have years of joy with it. It will out perform all of the overly complicated black anchors.

You'd be best off finding an expert in your neighborhood and don't be fooled by some wanna be. They can do more harm than good.

 

[r6speed]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Well I have the book for it but its not too helpfull when it comes to troublshooting. I most definately can't afford a marine mechanic nor do I think its worth the money you give them, i would rather try it myself and completely destroy it...it was only $900, if I take it in I'm sure the bill won't be below $900 I'm not willing to risk that. Does anyone know how to figure out what the problem is? Anything I can check or look at for obvious problems? Does anyone know what that electrical piece is I outlined in the pictures?

 

[WizeOne]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

The pictured switch is the shift interupt switch on the shift converter box. It simply, momentarily grounds out the ignition to enable you to pull the outdrive out of gear. If it adjusted properly, it only cuts the ignition when you pull it from forward back into neutral. The gears are cut in such a fashion as to constantly pull it into gear when engaged. You can only pull it back into neutral when you momentarily unload them.

Your description of what is occuring is not at all clear. Is the motor actually cutting out or is something slipping that allows the rpm to increase. I suppose that if the unit is actually trying to slip out of gear because of some wear, it could be causing backpressure on the drive shift cable causing the switch to activate.

I also suppose if the converter was not adjusted (calibrated) correctly, the outdrive may never be firmly engaged into forward gear. What manual do you have? and is it for the right series of drive? Selocs and Clymers are quite deficient.

You might make some temporary marks on the converter scale to denote the shift arm position in reverse, neutral and forward. Then disconnect the cable from your throttle shift control (at the converter arm) and manually move the lever into forward, then back into reverse and see if its stopping points are the same as when connected to your throttle/shift cable. Neutral should be dead center of those two outer marks.

If the two do not coincide then you need to adjust the ram on the shift cable til they do. You may also need to readjust the interupt switch at that point but you'll need to consult the manual for instructions on that.

 

[r6speed]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Well it sounds like that switch grounding out the ignition could be the problem maybe cause it goes hay wire when it happens. I have now adjusted the the arms on the linkage to dead center of the mark.

What is happening is not the motor cutting out really though, its like just for a split second the outdrive is hitting something in the water and jolting the whole boat, but only for just a split second then back to normal and it doesn't matter if I'm going slow or fast.

However your theory of backpressure on the drive shift cable causing the switch to activate could possibly be it?
I did what you said and it seems the boat is fully engaging in gear and when it jolts the motor does not rev nor die it is such a small amount of time it has no time to do anything it just keeps going.

I have the manual for this outdrive and the old one, but there is no troubleshooting techniques for this problem.

I am thinking about taking the boat to the water and taking video of what is happening, if I do that do you think it would make a big difference in understanding the problems?

 

[studdy05]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Overstroke switch adjustment is here.

That site can help you with your settings and some minor shift cable trouble shooting.

 

[WizeOne]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

.... I have now adjusted the the arms on the linkage to dead center of the mark.....

You did not read my post. Dead center of the 'mark' means nothing. Cables stretch, dead center shifts. You need to verify current dead center by determining deep forward and deep reverse with the throttle/shifter cable completely disconnected. But then I repeat myself.

Also be sure to read studdy05's link for the switch adjustment.

 

[r6speed]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Ok I had read that wrong, I appolagize. I will get out there and do that, thanks you for the help I will post results soon

 

[r6speed]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Ok I correctly adjusted the neutral adjustment or "converter" and running it out of water it is not jolting, I don't think it would in the water in that case either but I'm not 100% so I'm taking the boat out in the morning to see if it does it in water. On that site suggested above (guide I followed) it also explains how to adjust the electrical "overstroke switch" they call it so I will adjust that in the morning before I go just cause it can't hurt. I am taking my video camera also incase it keeps jolting.

Thanks for all the information its greatly appriciated!

 

[WizeOne]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Well, did the two sets of marks differ at all?

 

[r6speed]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Yes they did, I adjusted it again wrong once again and of course it didn't work, but once I realized how it all worked it was easy to understand how to adjust it so I got it all adjusted took it out and just like a dream she went!! Thanks a lot guys I really appriciate it!

 

[WizeOne]

Re: 74 OMC 250 -Jolting-slipping gear-shift linkage- problem need help newbie here

Good job!