Mercury Outboard Question ( Ryoken??) Resolved!

[Fordum]

Considered placing this in the lounge, but it is tech..........

Got a 2004 90hp Merc. on my friend's pontoon boat. We have the first fishing trip of the summer planned for next week, and I was out getting things ready.
Fuel is stabilized non-eth. Hooked the muff up and let the hose run for a while to get the impeller well wetted.
Pumped it up, carb unit, and started cranking. Took a while for it to start, but runs pretty good with a slight lope.
Put it in gear to mix the foot oil, and will check for milk later.

Spotted a problem:
On each side of the driveshaft housing, there is what looks like a freeze plug.
Dome head, not the hollow cup type.
The starboard one is leaking water around the lower half of the plug. I realize that a coolant leak is not a problem in this case, since its an open system, and the leak is not enough to compromise the total flow.

But, if it were to pop out, I suspect the engine would lose enough flow to overheat.
Its not under as much pressure as a closed cooling system would be, but its leaking around a lot of its circumference, which makes me worry that there is not much holding it in.

The other side is dry.

I was not all that concerned, its low pressure, easy to get to, I just figured I would go to my local Merc. dealer tomorrow and pick up a couple. Use the old slide hammer trick to pull the old one out, slather on some sealer or glue and tap in the new one.

If there happened to be a corrosion problem with the hole, I would use one of the rubber expanding ones to get us by the weekend.
Low heat, low pressure, should last years.

Started checking the web, and that is when things went sideways. Lots of motors do not show those plugs.
Using the correct model and serial number found a pic, but it shows it as a screw in plug of some kind.
With a Phillips or similar head.

This one is smooth, although the paint might have filled up the head. If it is a screw, its probably just loose. I can go back out and scrape the head to see if there is a way to tighten it.
But, before I start tinkering with it, I would like to know what is going on.

This is the best drawing I can find of it. Its part number 25. I can also go back out and take a pic of the one I have it it will help.





NOTE: It is in the driveshaft housing, NOT the foot.

 

[ryoken]

no crue... I get what your talking about, but have never seen that happen... I do a fair amount of maintenance, pumps, trim cylinders, yada on the OB's, but Eddie does most of the mechanical stuff these days..

it's above the pump, thus why it's pumping out.. and yeah, if it popped out, you'd be overheating more than likely..

I'll take a peak at a few I have kicking around the yard tomorrow and ask Eddie and get back to ya in the evening...

 

[Fordum]

I appreciate it. I figured it was a little out of your area. You might find it hard to find one on the yard.
Most of the diagrams I looked at did not have them. And the one for that model was for before or after a certain serial number.

Sounds like the afternoon thunderstorm is brewing up outside. I was going to go out later to see if it was really a screw and if it might have been loose, but I might better go sooner than that.
Lightning here at the farm is not something to fool around with.

 

[ryoken]

eh, it's a 50/50 shot.. really depends on what got dumped in the water last week, and what's still on land... I know the plug your talking about, I've noticed it before.. but have never messed with one...

 

[Fordum]

Well, its not a freeze type plug. I went back outside and I could rotate it with my thumbs.
Its shiny black against shiny black, so I was not sure how far it actually turned, but I guess I got a 1/4 to 3/4 turn on it. I tried to unscrew it, but it stopped turning. Then it did not seem to tighten as far back as it unscrewed.

About that time, a lightning bolt flashed followed by the thunder about 1/4 of a second later.
So, I made a calm, dignified, but rapid return to the house.......

There is a big squall brewing up just to the West, moving to the North. But it looks like it may either swing over me or just expand to cover my area. I am already in lightning range of it, so I will be suspending operations on the boat until after work tomorrow.

The Mercury part number seems to be: 19-8M0026580

Meanwhile, I got one pic before things got puckery.........

 

[Fordum]

Well, went by my outboard place this morning. The head shop mech., who has worked on tens of thousands of Mercs, told me he had no idea what it was........

Said that they only put them on a few motors, and that line only had them on the last year they made them.
However, he said that any water leaking around it was exhaust water, so if it blew out there would be no problem.

I had been afraid that it was in the cooling circuit between the pump and the block, but its after the block.
So, I'm going to ignore it.

He said that he had seen motors come in with them gone, and the owner had not even noticed.
Did not think he had ever actually replaced one.......

Thanks Ryoken, looks like I have one less thing to worry about.

 

[ryoken]

cool.. honestly, I'm soooo swamped, I forgot to even look today... but you do have my curiosity up when I get a few minutes..

 

[blazer74]

(Swamped) Is that a boating joke? Lol.

 

[ryoken]

I wish....

tho I do have dreams of drilling large holes in every boat bottom in the marina...



till the 4th of July, my days are pretty psycho...