Mercury 850 85hp. Good engine or stay away?

[Bman2895]

I run up a shallow arm of my lake and have not had that problem but i do not put on the tab.

When kicking over in the driveway before every trip, i do have to lower and prime. Raised to tabs and primed does not work.

82 model.

Oh I wasn't running it while up on the tabs. I'd kill it floating up to the bank go back pull the motor up put it on the tabs and then Coast it into the sand

 

[racerone]

The brown / copper decals were for 84 / 85 models.

 

[redneck joe]

try tightening the bolts/nuts for the motor mounts. If they squish in....

 

[Chris1956]

Those motors when tilted, leaked fuel out of the carb throats. The fuel sat in the lower cowling fuel drain "pan" until the motor was tilted down and then leaked into the water. Most of the time, you needed to reprime.

The PTT system on the 50HP motor is a bit different than the one original to the 850. I do not think they will interchange. The PTT system on the 115HP motor should work on the 850.

I would look into aftermarket PTT systems for that motor, as the original PTT systems took up space in the boat, the cylinders often leaked and repair kits were either not avail and if avail, were tricky to install without a special tool. Also, replacement PTT motors were hard to get. ARCO used to make them, but not sure if they still do.

 

[Texasmark]

The brown / copper decals were for 84 / 85 models.

Mine had Mercury spelled with a "lower case" m.......disqusted me every time I looked at it.......It had 3 stripes, silver, red, and one other color, blue I think, I forget.....they were beneath the name in a straight line from the front of the cowl straight back and at the rear turned down and cut off.

 

[Texasmark]

Those motors when tilted, leaked fuel out of the carb throats. The fuel sat in the lower cowling fuel drain "pan" until the motor was tilted down and then leaked into the water. Most of the time, you needed to reprime.

The PTT system on the 50HP motor is a bit different than the one original to the 850. I do not think they will interchange. The PTT system on the 115HP motor should work on the 850.

I would look into aftermarket PTT systems for that motor, as the original PTT systems took up space in the boat, the cylinders often leaked and repair kits were either not avail and if avail, were tricky to install without a special tool. Also, replacement PTT motors were hard to get. ARCO used to make them, but not sure if they still do.

Opinion: I think the 115 was just the 850 with an extra carb and a couple more pistons stacked on top.....with a 2:1 gear box. Having had both, The '88 115 I6 was liken to a well oiled sewing machine. Another mighty fine engine that loved to run my little Ranger "pad" boat at 50 MPH at 6k RPM. You could hear the engine singing and the prop humming since the blade tips were right at the surface at best trim....Mercury original Laser SS prop.

 

[redneck joe]

Ive looked for an aftermarket tnt system but havent found one that can handle a motor larger than 35 or so?

 

[Chris1956]

Mark, the 115HP IL6 was indeed an 850 with another carb and two more cylinders, labrinth seal and reed valves. The Mercs were modular in that way.

CMC used to make PTT systems for larger HP motors. They may not be the only ones.

 

[Bman2895]

Finally did the water pump today. It seemed to be fine, but I noticed the stream at idle was kinda lousy so I went ahead and did it.

Ill post some pics but I dont think there was actually anything wrong with my original one? Let me know if yall see something I dont.

Also I did some reading and put the engine in gear and pulled the foot. On the re install it just wouldn't quite mate back flush. I tried rotating the engine. Tried changing the gear I had the foot and motor in. F N R didn't seem to make a difference. Made sure the water pump tube was in. Verified the drive shaft was engaging and the shift shaft also was engaging. It just wanted to sit 1/2" ish off. It wasn't like a hard stop. You could push and it hold it and it would move together, but it always sprung back that little bit.

I went ahead and drew it together with the nuts. Like i say It wasn't like I was fighting to draw it together. And I was using a little wrench as to limit my force. Idk im kinda paranoid something was off? But I checked up in the mid section and the splints all looked good and wasn't any obstructions I could find. Also Verified the engine still spun freely and has all the gears.

 

[Bman2895]

 

[jimmbo]

The Impeller was long past its Best Before Date. I bet the New one didn't have bent Vanes
I just love Burry, out of Focus Pics, makes it easier to give parts a Pass.
You did get the Vanes curved it in correct direction, when you lowered the Housing over them

 

[Bman2895]

The Impeller was long past its Best Before Date. I bet the New one didn't have bent Vanes
I just love Burry, out of Focus Pics, makes it easier to give parts a Pass.
You did get the Vanes curved it in correct direction, when you lowered the Housing over them

Weird pics are clear on my end. And yes. Spun the lower clock wise as I installed the pump housing. Correct right?

 

[Chris1956]

CW is the correct direction. That is either an old Merc impeller or aftermarket. New Merc inpellers have resin instead of brass as the core of the impeller. Both work fine. It looks like your picture was of both the top and bottom of the impeller. The photos I saw did not show wear on the impeller, but after a while they tend to get a set in the vanes and don't pump as well.

I always install the gearcase with the motor in neutral, as it the gearshift "clicks" into neutral and doesn't move, making the mating of the shiftshafts easier.

Some gearcases had a spring-loaded driveshaft pin. do you have that?

 

[Bman2895]

CW is the correct direction. That is either an old Merc impeller or aftermarket. New Merc inpellers have resin instead of brass as the core of the impeller. Both work fine. It looks like your picture was of both the top and bottom of the impeller. The photos I saw did not show wear on the impeller, but after a while they tend to get a set in the vanes and don't pump as well.

I always install the gearcase with the motor in neutral, as it the gearshift "clicks" into neutral and doesn't move, making the mating of the shiftshafts easier.

Some gearcases had a spring-loaded driveshaft pin. do you have that?

That little pin in the end of the drive shaft? Yeah if thats what your talking about. It didn't really wanna move for me?

And I believe it to be the original OEM impeller. PO did say the boat hadn't been to the lake maybe 10 times since new in 1974.

Im keeping all the old parts in case this new one has an issue.

 

[racerone]

That impeller has taken a set.----Vanes do not flex.----Does not perform well at all.----It is scrap.

 

[Bman2895]

That impeller has taken a set.----Vanes do not flex.----Does not perform well at all.----It is scrap.

Gotcha. It's all new now.

And from what I read it seems I was fighting with that pin on the driveshaft.

 

[Bman2895]

Seems to have fixed the issue. A solid stream now at idle, but id have expected a bit more pressure on a new pump.

 

[jimmbo]

That design of Pump pressurizes the Cooling System to about 6 psi at 5000 rpm. Mercury's Water Pressure Gauges for the old Inline Motors, only read up to about 9 PSI. The V6s were a different matter