New Member with a Merc 800

[Bruiser61]

I've visited your forums many times over the last few years. I've always found it informative and spot on.
I recently got a pretty sweet deal on a 1990 Key West 1700 dual console with a 1978 Mercury model 800.
The hull was in very good condition for it's age. A few chips, gouges, dings and light spiderweb cracks. NO soft spots!!
The motor? Not so good. PO had started to working on it. As with most old mercs, the wiring crumbled at the slightest touch. Many wires were completely gone. Many wires just disconnected and hanging there. Lower unit removed, controls disconnected, etc.
The PO was in way over his head (more than I).

Because of the information on this forum and prior experience, I have been able to take care of a lot of the issues.
New stator and trigger assemblies.
Rewired the entire boat. I even found some household extension cord spliced in under the deck!!!

I'm getting close to completion. Just some problems I can't seem to work through. Hoping someone can offer the solution.

I do have a lot of pics, but I'm at work now and can't upload them. I will try to add them later today.

I've tried to get the lower unit back on (after replacing the impeller), no matter what I do, I can't get it to mate up with the mid section. About a half inch gap.

The mercury switch was gone. I replaced it. One wire to ground, the other???

The trim/tilt pump chatters in one direction like the solenoid is no good. I've tried two different solenoids with the same results.

Thanks in advance for you help and input!

 

[alldodge]

You didn't say what motor your working on other then something about old Merc's. Since its a motor issue we can see if GA_Boater can move it to the OB section for more help

 

[Bruiser61]

HMMMM,
As stated in the original post....
1978 Mercury Model 800.

 

[Sea Rider]

Meanwhile it's moved. Drive shaft is not getting inside the other power unit. Grease lightly the upper drive shaft's splines, push upwards the lover leg till won't go any further in, at same time, rotate gently the flywheel with hand, wrench CW. Drive shaft will surely snap in as a breeze...

Happy Boating

 

[alldodge]

woops, my bad. Just need it moved to the OB section which should happen shortly, then the OB guys can assist

 

[Bruiser61]

Thanks Sea Rider.
I'll give that a try this evening.

 

[Bruiser61]

Thanks AllDodge.
I had thought about posting there as well.
No problem that you didn't notice the info.
My old eyes fail me more than I care to tell.

 

[GA_Boater]

Howdy, Bruiser.

Moved the original into the Merc outboard section, so it's taken care of.

On the mercury switch - As you found, one wire to ground and the other goes to the ignition system, either the switchbox or magneto to kill the motor if it's tilted too high where a spinning prop can hurt someone or the water inlets are high and dry. Gotta dig in the wiring diagrams for the connection.

On mating the lower unit to the midsection. A 1/2 gap sounds like either shift shaft or water tube alignment. Quite a few of us have found using neutral instead of forward works better to mate the shift shaft. A helpful tip - https://forums.iboats.com/forum/eng...od-of-shift-shaft-setup-for-mercury-outboards

For the water tube, what works best for me is to stick in the motor and let it hang. When I offer the lower unit, the driveshaft meshes first and with the plugs out, turn the flywheel slightly until the lower goes a little higher. Then using a thin screwdriver in the gap, move the water tube and shift shaft slightly to align with the water pump and upper shift shaft.

Also I use a floor jack to support and raise the lower unit. Once the driveshaft and motor are meshed, the jack hold it in place to fiddle with the water tube and shift alignment. No forcing - When it's lined up the lower slides up like butta.

Hope this helps. Gonna look for the wiring and maybe merc850 is around, I think he's posts the wiring diagram.

 

[GA_Boater]

Mercury switch wiring;



The other orange wire is from the plug on the side of the motor and goes to the key switch.

On the TnT chatter - Check the fluid level in the trim pump and look at the rods on the trim cylinders for rust or roughness. Also put a little trim fluid on the rods - The seals may be dry from sitting and need a little help until the juice is circulating again.

 

[Bruiser61]

Thanks GA_Boater.
I figured the second wire from the mercury switch went to the switch box, just didn't know where.
I think the chatter sound is something electrical. But, I'll fill and lube the pump and all rams and give it another go.

 

[Bruiser61]

Well, as usual, work got in the way. I hate when that happens!
At any rate, I haven't had the time to work on my issues as yet.
I've got a buddy coming over on Saturday to lend a hand and to bring the beer.
I'll update when the work is done or the beer is gone, whichever comes first.

 

[Bruiser1956]

Forgot to post an update (I'll blame it on too much beer)

I was able to get the lower unit back on. Thanks for the tips!

The mercury switch wired in and working as it should. Again, thanks for those tips!

The trim/tilt pump still chatters in one direction (although the motor doesn't move). This one is a head scratcher.

If anyone else has any ideas, I'd love to hear them.

Thanks

 

[Chris1956]

A lot of those PTT units had a single solenoid for the up direction. Solenoids do make a noise that you could describe as a chatter.

Also, the solenoid is wired thru a trim limit switch. These usually break, but I guess it could be intermittent. If you have the three button trim control, push the middle and top buttons together to bypass the trim limit switch.