Struggling with Mercury 3.3hp 2 stroke repair

[bobgarrett]

I am struggling with a Mercury 3.3hp 2 stroke repair.
Trying to get the gear box off the bottom of the leg to replace the impeller I have already stripped the bolt top off the two bolts despite soaking them for weeks with WD40 penetrant.
Now I cannot get the bottom part to separate from the drive leg despite some hefty thumps with a big rubber hammer. I am worried about damaging it with a metal hammer.
I note there seem to be two small rectangular holes near the front, should these have something inserted? But how robust is the metal.
Any idea how to get this apart?

[ggray]

I've been watching this as I have an old Merc 3.3 that I'm planning to pull out of the barn and use again. Hope I don't have your issue.

Assuming you get it apart, you might look at this thread of some years back. A difficulty of "pumping" oil into the lower unit. Mine has this problem.

https://www.cruisersforum.com/forums...de-158524.html

[Lepke]

I got one. It's been wall art for about 5 years and I bought an electric. The electric cost less than the usual outboard shop fee.

[James M B]

Did you disconnect the gear shift rod? There is a round hole cover (shows in your picture) you open and through that hole disconnect the gear shift rod.

[bobgarrett]

I have not disconnected the gear control rod yet but will if I could get any movement on the leg bottom.

[tedban]

So the bolts are probably seized to the aluminum. I think on my 15hp there were also two pins. I hammered a screwdriver and chisel gently into that rectangular hole and also used a punch and hammer to separate the case. A little heat from a propane torch would probably help

[nuku34]

Its to late for this advice, BUT anyone buying a new or newish small outboard should first of all remove EVERY bolt you can get at and apply anti-seize compound to them, then put them back (using a small torque wrench set for the diameter of the various bolts so you don’t strip the threads in the alloy). Mercury, and probably every other outboard manufacturer, does not put anti-seize on the bolts when the outboards are assembled. This insures that in time the stainless bolts will corrode the alloy female threads and be a bitch to get out.
Why do they do this? Save a few bucks on the assembly time and materials, or maybe they have a secret deal with the service people who get to fix all the sheared off bolts and/or replace the alloy castings when the DIY folks give up on fixing them.

[Jammer]

Originally Posted by bobgarrett

I am struggling with a Mercury 3.3hp 2 stroke repair.
Trying to get the gear box off the bottom of the leg to replace the impeller I have already stripped the bolt top off the two bolts despite soaking them for weeks with WD40 penetrant.

The way forward if you're going to invest the time to try to salvage both castings is to carefully center punch and drill the bolts, marking the bit so that you stop drilling before reaching the threads. You would start with a drill about half the size of the bolt and go up 1/64" at a time until you reach the casting. Once that's done it should be possible to knock the casting loose. Then you can center punch and drill the bolts in the lower unit and maybe get them out with a screw extractor, if not you drill them and put in a Helicoil.


It's difficult, it's a lot of work, and you may not be able to get a straight shot with a drill.


I would seriously consider getting a used lower unit (check ebay) and cutting into the existing one just below the mating surface, cutting through the bolts, using a die grinder (if you have one) or a hacksaw (otherwise). Once you've done that a 2 pound hammer will remove what's left (remember to undo the shift linkage).

[Dave_S]

Ha, this thread caught my eye because I'm doing the exact same job today. I thought I was in for a nice easy day.

🤬

Maybe I'll do it another day 🙂. I could just watch tele and drink rum and not break anything.

[stormalong]

Those engines were made by Tohatu. I have owned a few versions of this engine with different brand names and engine cover shapes. The earlier ones had no anti seize when built. My current one, which I bought new in 2007 was assembled with anti seize. I took it apart right after buying it to put anti seize in and was pleasantly surprised that it was already done.

[Jammer]

Originally Posted by Dave_S

Ha, this thread caught my eye because I'm doing the exact same job today. I thought I was in for a nice easy day.

🤬

Maybe I'll do it another day 🙂. I could just watch tele and drink rum and not break anything.

I just yesterday got a spreader bolt loose. I had been spraying it with penetrating oil every few days for the last three weeks. Yesterday it moved just a tiny bit, and I rocked it back and forth, less than 1/10 of a turn at a time, until it freed up. Same situation, stainless steel bolt in contact with aluminum.


Use good penetrating oil, not WD-40 or motor oil. I use JB-80. There are other good ones. Be patient. It may take weeks. Apply penetrating oil daily if possible. Work the bolt in both directions, carefully, gently, until it comes loose. Don't twist the bolt apart, that makes matters worse.

[Pete7]

Originally Posted by nuku34

Why do they do this?

They don't want you to fix it, they want you to buy a new engine, they are after all in business to sell outboard engines. If everyone fixed their engines, then who buys the mew ones.

Pete

[Dave_S]

I pulled mine apart today. It came apart ok but with some resistance on the 4 housing bolts so I was feeling pretty smug that I had got it in time.

Yeah, should have known better, I just bought the impeller, not the full kit. The cup that the impeller runs in has a blister in the coating so it will destroy the new impeller in a few revolutions 🤮. Back to the shop tomorrow.

[Jammer]

Originally Posted by Pete7

They don't want you to fix it, they want you to buy a new engine, they are after all in business to sell outboard engines. If everyone fixed their engines, then who buys the mew ones.

Pete

Never ascribe to malice what is adequately explained by....


If you are in the business of producing something as mechanically complicated as an outboard motor in relatively small quantities (compared to, say, refrigerators or cars) then it is incredibly difficult to get details like this right, consistently, across a wide range of models and with constant turnover of assembly staff, with constant changes in parts availability, with the cost pressure due to the competitive landscape.

[nuku34]

So, a tiny bit of anti-seize on each bolt + an extra 5 seconds per bolt is going to be a "cost pressure"? I'd pay an extra $15 for a new ob I knew had anti-seize on all the bolts. But then I buy for reliability, ease of maintenance, and quality, not price. Generally you get what you pay for.