Questions about '75 Merc 75

[Buzzwindrip]

I just picked up a 1975 Mercury 75 - ser# 4091049- for $25 on Craigslist. Sold by the original owner, who said it hasn't been run in a long time, and couldn't say if it ran or not. I have not tried starting it yet either, as I wanted to pull the plugs and check the lube in the gearcase before doing that. The foam sound deadening material in the cowl is deteriorated, and I want to pull that out as well.
Some questions: The manual refers to "grease" for the gear case. Isn't just hypoid gear oil in there? Is there a suitable automotive gear lube to replace it with? What viscosity?
The motor was fairly clean under the cowl, but in the grime that is in there, there appears to be some fine metal flakes scattered around. I can see some on top of recoil starter too. Normal, or is there something grinding away that will be an expensive repair?
Where the heck is the motor side fuel filter? The fuel line runs to a blue plastic cover on the left side of the carb. I assumed the filter was under there, pulled it, and nothing. Just some holes. Is the filter under the plate that has the 4 screws on the left side of the carb? The manual refers to the filter cover, as if it is easy to get at.
There is a plastic rod that extends up from the front of the LU. It ends in the vicinity of the clamp, but is connected to nothing. Is this the reverse lock in a broken state?
All wiring and fuel lines look to be in good shape. There is one hose, between the base of the power head and the vicinity of one of cylinder heads that has cracks in it. Can anyone tell me what that line is?
I took a chance on the motor, as did 17 other wannabe buyers, hoping to have scored a gem on the cheap. I was about to replace the gas tank, as it is rusty on the inside, but will hold off till I find out if the metal dust is a show stopper. I am going to clean the gas tank and filter the best I can, and try starting it. If it is a no-go, I would just relist it rather than dump a pile of cash into it. Any help appreciated in the meantime.

Glenn / Cudahy, WI

 

[corm]

Re: Questions about '75 Merc 75

Hi,

Its junk.
I'll give ya your $25 for it.

 

[corm]

Re: Questions about '75 Merc 75

Hi,

I forgot about your questions.
The filter was under the blue cover until someone lost it.
The metal is from weak wave washer allowing the starter pawls to bounce off the flywheel. Pretty normal on these engines.
The plastic rod is part of you reverse lock. There is a slot that it goes into and a clip that holds it in. The clip is in the lake. The next one you put in will be in the lake too. Unless you can find a metal rod to replace the plastic one with. I would not bother or waste the time on it. I am sure it is NLA.
You probably should put a water pump in it if it runs ok in garbage can.

 

[Buzzwindrip]

Re: Questions about '75 Merc 75

Hi,

Its junk.
I'll give ya your $25 for it.

Yeah, there were 17 replies to the OT that posted it origianlly. Thanks for the tip on the filter. What was it, a fine screen in a disk shape?
I have a WTB on the local C-list for a used tank. I can get a new tank for $30, but then I have more invested than I care to in the event it won't run.
Glad to hear the metal bits are normal!
If it does start and run, I will tackle any impeller issues. Thanks for the reply.

 

[corm]

Re: Questions about '75 Merc 75

Hi,

The screen was round and just under the dia of the cover.
It fit under the cork gasket that seals the cover. If I remember right
there is a slight recess in the metal pump body that it fit into.
I'd put in an little inline myself if I did not have any fine mesh around.

 

[Buzzwindrip]

Re: Questions about '75 Merc 75

I picked up a cheap Attwood plastic tank today, swapped the old hose to the new tank, added some 50:1 gas I have mixed for my sailboat kicker, and after 4 pulls this thing fired up. It runs a bit rough at low speed, but I do have new plugs for it to try. At first I thought the impeller was shot, as the indicator was the last to the party. The stream was good, FWIW, but it did stop and restart a few times at idle.
One more question: it seems there was some exhaust escaping from the indicator port during the few times the water flow stopped. Normal, or bad head gasket? I will definitely be replacing the impeller now that I know that this thing actually runs.

 

[corm]

Re: Questions about '75 Merc 75

Hi,

If you were running it in a container it could have been sucking exhaust into the water system. The water intake is above the prop so this can happen once in a while. This engine does not have a head gasket.

 

[Buzzwindrip]

Re: Questions about '75 Merc 75

Hi,

If you were running it in a container it could have been sucking exhaust into the water system. The water intake is above the prop so this can happen once in a while. This engine does not have a head gasket.

That makes sense. I had it in a tub, and there was definitely exhaust bubbling up and under the cavitation plate.
Gee, looks like I got lucky twice on outboards. Now if only the rest of life worked that well...

Thanks for the help corm!