I Got Me a Mercury !!!

[tpenfield]

Re: I Got Me a Mercury !!!

Also, it seems like there is a fair amount of oil in/around the water pump. . . I am wondering if there is also a seal needing replacement there. :noidea:

 

[GA_Boater]

Re: I Got Me a Mercury !!!

You better get a book. There are three sets of seals - Shift shaft, prop shaft/carrier and water pump/drive shaft seals. The shift shaft and prop shaft/carrier seals are on the parts diagram in post #56, the water pump/drive shaft seals are usually in a full water pump kit, which wouldn't be a bad idea to do anyway.

 

[matt167]

Re: I Got Me a Mercury !!!

This covers the shift shaft seal and water pump on a Classic 50. Not the same but close enough if you back it up with a manual

 

[tpenfield]

Re: I Got Me a Mercury !!!

Another Update:

I went into town today to see if I could get a maintenance manual for the Mercury 7.5 HP as well as the couple of seals. Struck out on the maintenance manual, but I managed to get the 2 seals at the Mercury dealer.

So, without the manual, I just had to wing it. . . I replaced both the shift shaft seal and the drive shaft seal. I got it all put back together and filled the LU with new gear oil. The old oil looked old (black), but was not milky.

I plan on testing the engine tomorrow. . . . so hopefully it will work out.

 

[tpenfield]

Re: I Got Me a Mercury !!!

Here is a look at the Old and New drive shaft seal. As you can see, the old one was really worn and really not making much of a seal with the shaft.



The 2 seals were about $18 total at the Mercury dealer. Surprisingly, they had them in stock.

 

[jbjennings]

Re: I Got Me a Mercury !!!

What did the shaft look like? Deep grooves or rust pitted?
If the oil was black, it was just old and not changed in a while. If it were not milky or had no clear water in it, it likely wasn't leaking. Still not a bad idea at all to change the seals.
I think a lot of your oil you are seeing is just unburnt fuel/oil that is draining down the inside of the motor leg. Some of it is just seeping out the seam. There's a lot of unburnt fuel on a 2-stroke, especially if it's running rich. Synthetic oil will help a lot if it bothers you.

 

[tpenfield]

Re: I Got Me a Mercury !!!

What did the shaft look like? Deep grooves or rust pitted?
If the oil was black, it was just old and not changed in a while. If it were not milky or had no clear water in it, it likely wasn't leaking. Still not a bad idea at all to change the seals.
I think a lot of your oil you are seeing is just unburnt fuel/oil that is draining down the inside of the motor leg. Some of it is just seeping out the seam. There's a lot of unburnt fuel on a 2-stroke, especially if it's running rich. Synthetic oil will help a lot if it bothers you.

The drive shaft had some pits in it around where it goes through the water pump housing. The part where it seals was OK. The shift shaft was rusty up in the mid-section. When I left the LU inverted for a day, as shown in the pictures; I got visible oil out of the shift shaft seal and milky oil out of the water pump.

I ran the motor quite a bit yesterday and only got a sheen on the water when starting, so probably unburnt fuel. I may try to set the idle needle as you have suggested.

I will monitor the LU for the presence of oil when it is tilted up for several days, and I may take a closer look at the prop shaft seal at some point.

For kicks, I made a short video of a WOT run yesterday.

 

[tpenfield]

Re: I Got Me a Mercury !!!

Update:

I had the engine in the 'tilted up' position for the past few days. So, today I went to use it and checked for oil on the lower unit, etc.

I noticed oil, from what I believe to be the exhaust discharge on the leading edge. However, no lower unit oil, as the new stuff that I put in is that emerald green color, and the stuff I got off the leading edge of the lower unit was definitely brown. So, probably just the expended oil from the engine, etc. So, I think that it is just a natural thing for those engine to leak the exhaust oil at the seam for the lower unit.

Anyway, I not much of a oil film when starting this time and no puking of oil. So, that is a good thing.

I did take a look at the oil that I drained from the lower unit last week, and there is a small amount of water in there, but it did not do the milk shake thing.

I also set the idle needle on the carburetor, as that was a little on the rich side.

 

[tpenfield]

Reviving this thread from 12 years ago . . .

My beloved Mercury 7.5 HP (1969 vintage) pretty much bit the dust at the end of last season. I decided that its tour of duty was up and it is honorably relegated to the spare parts bin.
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I have been scouring the Internet over that past week for its replacement. I came across a listing of a 1973 7.5 hp Mercury . . . I reached out to the seller and made an arrangement to go see it (cash in hand). I did a spark test and a compression test, both of which were fine. Cash on the table and in the car it went.
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$175 . . . I had wanted to get a mid-1980's 7.5 or 9.8, but it just didn't turn out that way (unless I wanted to go to $500 )

It took a little bit of coaxing (OK a lot of coaxing), but I got it started after about an hour of fussing with it. I'm going to swap the lower unit which has the SS drive shaft and a newer impeller. The 'new'/blue merc sort of pumps water, but not much. I suspect the impeller is pretty much toast.

Anyway . . . I got a few (modified) parts to swap over to this motor from my old outboard. Namely the stainless steel drive shaft (from a 1980 motor) and the stainless steel swivel pin/assembly that I made (all by myself).

The 1973 model has a few nice upgrades from my 1969 version. . . .

Electronic ignition.
Better tilt mechanism.
Better water circulation/pee hole.

Some of the fuel system hoses are leaking, so I may see what I can re-purpose from the old engine. I also plan on running a heavy dose of fuel system cleaner and some Mercury Powertune through the engine.

Hopefully, I'll get quite a few years out of this motor . . . We shall see.

 

[Grub54891]

Do me a big favor: never let go of the tiller handle while the motor is running! It only takes .100th of a second to have a disaster! I was foolish once, the motor jackknifed and threw me into the bottom of the boat. I was very lucky I didn’t get thrown out.

 

[racerone]

These little Merc's need a new impeller every 3 years.

 

[tpenfield]

These little Merc's need a new impeller every 3 years.

Yup . . . They do.

 

[tpenfield]

Do me a big favor: never let go of the tiller handle while the motor is running! It only takes .100th of a second to have a disaster! I was foolish once, the motor jackknifed and threw me into the bottom of the boat. I was very lucky I didn’t get thrown out.

You need the lane-keeping function . . . oh wait-a-sec . . . that is with cars

 

[tpenfield]

Yesterday, the motor needed a squirt of fuel to get it started, but today, after running all sorts of fuel system and combustion chamber cleaner through the engine, it started on the first pull. I got to do a little more work, prepping it for 'action'.

I decided to give it a fresh coat of paint this morning . . . almost good a new.
.

 

[redneck joe]

Man, wish I'd known. I just gave mine away a couple weeks ago and I had done all the reviving stuff already.

 

[jimmbo]

The 68 and 69 Decals, were the Best Mercury ever put on their Motors.

 

[tpenfield]

After some frustration this morning I got the new-2-me Mercury mounted on the dinghy and went out to the boat to check on things. This motor is a 1972-73 vintage (Serial number 337XXXX). It has the larger fuel fitting.
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I had run the motor on my old plugs, because I wasn't sure about the 'lifetime' plugs that it came with. I put the original plugs (AC V40FFM) back in and it ran fine in my test tank. This morning not so much. It was a no-go down at the dock.

I put the old/rusty plugs from my 1969 Merc (Champion L86C) in and it started right up.

I'll be going out today/tomorrow to grab a new set of plugs.

I plan on parting out my 1969 vintage motor and use the $$$ to grab a 4-6 hp motor.

 

[redneck joe]

You got my nomination for the ugliest dingy I've ever seen.

 

[airshot]

what dingy looks heavy....is it ?

 

[tpenfield]

what dingy looks heavy....is it ?

It's gotten heavy . . . I think the foam is getting water logged. Might be time for a re-fresh.

I made this dinghy and designed it to be self-bailing, which it is . . . just not well enough any more.