1974 Merc 1150 Lower Unit Busted?

[eggs712]

I recently purchased a '74 Merc 1150 really cheap. It has good compression, strong spark on all cylinders, and a nice SS prop. However, it seems to have some serious lower unit issues.

I drained the gear oil before ever starting the motor, and about 80% was water, which immediately alerted me that something could be wrong with it (it freezes here frequently during winter). I filled it up with some fresh gear oil and fired it up on muffs. She started easily, but wasn't pumping water so I killed it within 15 seconds of starting it. I next dropped the lower unit to change the impeller and water pump gaskets, putting the throttle in forward before dropping the unit. I've noticed something startling about the unit now; the shifter won't move from forward gear. I've changed impeller on an inline six before and the shifter easily worked by hand, but this one is solidly stuck in forward. I went ahead and changed the impeller and bolted the lower unit back on. However, it still won't move out of forward gear. The control box works as it should, and I can see the cables working properly in the engine. Yet the prop will only turn CCW like in forward gear no matter what I shift to. What's strange to me about this is that I can see the shift cable working properly, and it makes a clunking noise when changing gear as it should.

Another possibly notable thing is that the anti-reverse lock isn't properly working. The motor doesn't have power tilt/trim, and the reverse lock is supposed to release only in forward gear to allow the engine to lift. However, it's released no matter what gear I shift to now, allowing the motor to lift in any gear.

Does anyone know what's going on here?

 

[carholme]

Re: 1974 Merc 1150 Lower Unit Busted?

Did you ensure the correct positioning of the reverse lock cam on the lower shift shaft prior to installation of the LU or was there damage to the cam, seen here as item 46:

Mercury, Mercruiser, Force, etc. - GEAR HOUSING ASSEMBLY, COMPLETE (PAGE 1) - MERC 1150

Here is a link to the condensed version of the Clymer manual. Download it soonest to your computer as the link is short lived.

MERCURY - MERCURY IN-LINE SIX-CYLINDER MODELS (1969-1988).: Small Engine Repair Reference Center Home

See Fig M14-53 on page 316.

Gerry

 

[Chris1956]

Re: 1974 Merc 1150 Lower Unit Busted?

Eggs, Remove the gearcase and gently try to turn the shifter with a crescent wrench. It should turn CCW, and click into neutral.

 

[eggs712]

Re: 1974 Merc 1150 Lower Unit Busted?

Thanks for the replies, guys. I dropped the lower again and was able to shift into neutral with a wrench. I then put the control box in neutral, reinstalled the unit, and now everything works properly again.

However, it still didn't pump water when I fired it up. The lower unit doesn't make any weird noises, but I did notice one odd thing; there was water pouring straight from the propshaft when the water hose was on. Do y'all know what the problem may be?

 

[racerone]

Re: 1974 Merc 1150 Lower Unit Busted?

Question, is the exhaust cover getting hot ?------Is the overboard hose plugged ?-------These wee hoses plug up all the time.-Motor will cool just fine with the wee hose plugged up.

 

[eggs712]

Re: 1974 Merc 1150 Lower Unit Busted?

It only ran for about 10 seconds, but no it did not get hot to the touch. The hose plugging is a good possibility! The boat sat uncovered outside for months, and it may be caked in dust; I'll try cleaning it out and see if that fixes it.

Is the water pouring from the propshaft any reason to be concerned?

 

[Chris1956]

Re: 1974 Merc 1150 Lower Unit Busted?

Water should exit from the prop shaft and the gratings above the antiventilation plate. The telltales get clogged all the time. Remove the wrap cowl and pull off the telltale hose and see if water is exiting from the cylinder head water jacket.

Water in the gearcase could be leaking past the seal in the waterpump base. It would be a good idea to replace the waterpump base, so the seal is new. Clean up the driveshaft with sandpaper and lube it with grease. Now remove the waterpump base and replace it.

 

[racerone]

Re: 1974 Merc 1150 Lower Unit Busted?

Water pouring out at the propshaft is very normal.-------You need to address water in the gearcase.------------Pull it apart / inspect and if all parts are still usable you may be lucky.---Order a seal kit and install that it.

 

[eggs712]

Re: 1974 Merc 1150 Lower Unit Busted?

Thanks for the help guys. The peehole was indeed clogged, and now pees a good stream of water as it should.

Like racer said, I'm gonna next install lower unit seals to address the issue of all of the water in the lower unit. Hopefully the gears weren't ruined by the water.