1985 Mercury 75 hp very weak stream

[Gimmyabeer]

Hello,
I have an '85 Merc 75 hp. It has a very weak stream from the pisser hole (?). We changed the impellar with no change. While we were running it we noticed water coming out of the exhaust ports. Just bought it last year, it's my first, so I'm not sure if it's missing something. Also while draining the gear lube, it had a very bad smell to it. We were thinking maybe gears burning?
Any help would be appreciated.
Thanks,
Tim

 

[Chris1956]

Re: 1985 Mercury 75 hp very weak stream

Tim, The gear oil does smell of sulfer, normally. Get a qt of marine gear oil for mechanical shift engines. Smell the new stuff. Does it smell the same as the old stuff?

When you replaced the impeller, did you use new gaskets and a new wearplate? Did you remember to install the key that drives the impeller?

 

[Gimmyabeer]

Re: 1985 Mercury 75 hp very weak stream

Yes, I replaced everything that came with the kit. My brother in law has a 50 hp Merc (same year) and his has a good stream and no water comes out of his vents. His stream is warm also where as mine feels as cold as the water going into it.

 

[Chris1956]

Re: 1985 Mercury 75 hp very weak stream

Tim, most inline Merc motors do not have thermostats, so cold water exiting is normal. When you say exhaust ports you mean the exhaust relief ports high up on the midsection, just below the powerhead? Water will exit there normally, when ideling in the water.

 

[carholme]

Re: 1985 Mercury 75 hp very weak stream

Do the easy things first. Get a piece of lawn trimmer string and shove it up the p tube to see if you can free any blockages caused by mud daubers who love to nest in that tube.

Gerry

 

[cr2k]

Re: 1985 Mercury 75 hp very weak stream

Trimmer string or if you have a compressor shoot some air up there.

Did you turn the shaft the clockwise when you put the housing on the impeller?

 

[Gimmyabeer]

Re: 1985 Mercury 75 hp very weak stream

Yes sir, those are the ports I'm talking about.

 

[Gimmyabeer]

Re: 1985 Mercury 75 hp very weak stream

What would happen if the impellar was put it wrong? I think we did it right, just wondering.

 

[brnschoneck]

Re: 1985 Mercury 75 hp very weak stream

it probably wouldnt shoot out at all ..I have a 65 and my stream is wake always and when going faster it kinda spurts out not a even stream ..I beleive it is normal as long as u put a new impellar in you should be fine ...they dont shoot out like ur newer 4 swtrokes

 

[emckelvy]

Re: 1985 Mercury 75 hp very weak stream

It doesn't matter on a new impeller if you happened to twist the blades backwards, as soon as the motor is started they will flex over and be pointed in the proper direction. Note that you should never reverse the rotation of a used impeller, however, as the blades will have taken a set and you stand the risk of breaking blades and sending impeller pieces into your cooling system (not a good thing!).

That being said, the best way to clear the telltale is a good blast of air. You can also tell if water is circulating thru the block by feeling the exhaust cover (large plate on the Port side of the block). It should be cool to the touch or barely lukewarm. After a hard run it may be a bit warmer than that, but since the motor doesn't have a thermostat it should never, ever be so hot that you can't hold your hand on it. And should cool down pretty good once you're idling for a while.

Water blowing out the exhaust reliefs is a good sign that you're pumping a lot of water.

If you truly are having cooling issues as noted by too-warm block temps, pull the lower unit and inspect the impeller and also the pump plate and stainless "cup" insert. If the plate or insert are badly worn, it'll reduce pumping efficiency, even with a new impeller. Also inspect the water tube grommet for wear. With the lower unit off, you can blow air up the water tube or even connect a garden hose & flow water thru the motor.

But I suspect it's just a partially plugged telltale, a very common problem.

HTH & let us know how things go.........ed

 

[Gimmyabeer]

Re: 1985 Mercury 75 hp very weak stream

Thanks Ed, I'll try blowing it out after work tonight.