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Submitted By: fixb52s
Date Created: 05-15-2008
Description: Everything mechanical needs help now and then. This boat is no exception. As with the nature of boats, this just loves to challange me.
Related Projects: 1986 Chris Craft Scorpion 178 BR
    Deck and stringer repairs
    Sea trial
    Hull restoration
Tools / Materials: Go to the Boating Store

3.0 140 HP
This is what came in this boat. A good old GM iron duke packaged as a 140 Mercruiser Alpha 1. It ran OK but stumbled on acceleration.

The outdrive is a 1.98:1 and seemed to work.

The exhaust bellows was gone, and the u-joint bellows was torn. The bellows are nothing but seals that keep water out of the drive. The exhaust bellows is not a show stopper (it directs exhaust through the prop) but the u-joint bellows must be good or else water will get to the driveshaft and drive, killing it in no time. The trim switches also have bad wires. There are 2 of them, one that connects to the trim gauge and the other to the tilt motor, stopping the drive at full up and down. These have to be replaced.

I had to remove the drive to replace the bellows. While in there, I also replaced the gimble bearing. This bearing is what the driveshaft rides in. I did not take any photos of all of this. After the work was done, an alignment tool must be used to ensure the bearing is centered and the engine is in alignment with the driveshaft. If it is out of alignment, the drive would not go in. The engine front mount is adjusted up or down to bring it in alighment.
Alignment tool

New outdrive
After the drive was reinstalled, it was found to be locked up. I took it back off to see what was up. Somehow, a pinion gear broke in half. I also found the needle bearings very loose, so the drive would need a rebuild. I found this 2 year old Sterndrive Engineering aftermarket SE-106 drive (with the correct drive ratio) on Craigslist for a lot less than a new one. It would have cost more to have the old unit rebuilt, so I made out like a bandit with this (A LOT of good luck that day). The stainless steel prop that came with it would be too agressive for my boat, so I swapped it with the old one.

Since I didn't know the condition of the fuel pump filter, I decided to open it up for a look.
Fuel pump

Shot filter
The filter was clogged up, so it will be replaced.

The rest of the pump showed some hard deposits, so it was cleaned up and the rubber replaced.
More solid junk

New filter
Now the pump should provide enough fuel.

I took the carb apart and found a lot of hard deposits. Some passages were completely blocked. After a good cleaning, the passages were blown out with compressed air to ensure they flowed. The float was adjusted, and it was put together with new parts from a kit. It is VERY important that it goes back together completely. The kit came with a diagram that showed an exploded drawing of it, but it seemed to be missing a check ball and spring that were on the carb when it came apart. I looked in the Mercruiser shop manual and it showed these. The kit did come with them, so it was weird that it was not shown. The kits will work with a few different variations of this carb, so ensure you have the proper book for yours.
Carb rebuild

Fuel line
The old line was cut and had a ruber splice in it. It was also collasped by the carb intake, so the new one will be installed. Parts are still avalable for these engines.

This engine still uses points and condensor, so both were replaced. The point gap was set at .022, and the dwell was checked with the engine running to ensure it was correct. The dwell will show if the proper point gap is set. Cars in the 80 did not see old style ignition systems like this (they went electronic around 75) but the boats still use them. I will eventually update this distributor with an electronic unit in the future. The conversion kit installs in place of the points and condensor, and will not wear out like points do. A lot of automotive mechanics today have no clue about point type ignitions, and look at a dwell meter like it is a UFO. I still own a dwell meter and timing light, and they sure did come in handy. The cap and rotor were also replaced.

Plug wires
The plug wires are not correct for this engine. They look like they belong to an OHV engine because of the long boots. I thought they would be OK for now, but when I ran the boat on the water for the first time, it stumbled, shook, and would not go over 1500 RPM in gear. I found 2 plug wires pulled from the plugs. When the engine is running, they work their way loose due to the extended boots.

New plugs and wires were installed. Runs much better.

More problems
When I took the boat on the water, I found it was stalling when I tried to throttle up. The lower shift cable was binding and kinked. I was replacing the cable and found that the cable was "glued" into the bell housing with some type of thread repair material. The cable guide was stuck and wold not come out. I drilled and tried to use an easy out, and it only made things worse.

I could have taken it to a machine shop for a helicoil, but it was cheaper to get this transom assembly. I got the whole thing for $50 from the same guy who sold me the SEI drive. It is nice to live in Florida close to boat boneyards. Before I took it home, we removed the cable and ensured the threads were good. It was in salt water, but is in good shape. I only needed the bell housing, and the hinge pins were broken and STUCK. The pin socket would not turn the pins since there was no grip. The gimbal ring was cracked so it was cut to remove the housing, and the metal around the pins was heated with a torch. A pair of vicegrips on the pins, along with the socket was enough to get them out. I could have drilled the bolts and used an extractor tool, but this was quicker. All the threads were chased with a tap, and the housing was installed. Once installed, the shift cable was replaced, and this glitch is finished.

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