Sudden power loss with prop. or something else??

[gljjr]

I agree Dan, coincidence is very rare when it comes to motors. Something changed that seems to have fixed the problem.

I still have a hard time believing it was the thermostat. Especially since it seems to have worked fine on the stove when in a pot of water. More likely is that it truely was an electrical problem and by doing the R & R on the thermostat the wires got moved and no longer have a bad connection.

[digger]

Usually, erratic problems like you have described are caused by a bad ground wire. It can make the brains of the motor dumb, including bad tach readings. Check the ground wires within the motor cowling. Usually black, or black with white stripe. Could be banana connectors, or loose ground bolt on the block. You can pull the connectors apart, put a little silicone grease on them, and push them back together. Good luck. Ron

[primative]

Rene here (aka, the wife) weighing in.

Dan, Gary, thanks for your positive spin and to all who have taken the time to read and reread this complex problem of ours and offer responses. We are rereading them, too!

It would be lovely to believe that our motor troubles are over, and we are enjoying this reprieve, but considering the history... last summer this problem resurfaced in June. ...then after not being able to reproduce it at the shop, Tom used the boat to fish in the Ocean through the Astoria bar for three consecutive days in July with no problem... then we fished outside the Garabaldi bar in August another three days, again no problem. But last fall it reoccurred on a trip on the Columbia in September and again in October on the John Day River. Everything since then has been well documented in this thread.

If we were using the motor more often perhaps we would make faster diagnostic progress, but work gets in the way. We are happy that the motor doesn’t leave us stranded, but also very fortunate that it hasn’t usually acted up when we have a long distance to go. This did happen once a few years ago on our last day of camping about 10 miles out on the northwest side of Vancouver Island and we limped back with a very full load of people and gear.

The other blessing is that it has given Tom a reason to learn more about the motor. I’m very proud of him for doing his own mechanical work, and it gives us confidence considering we like to go places where we can’t count on there being folks to help us. He has started by replacing the least costly parts. The part that is the brain (for both the temp and the tac), the control box, is quite expensive to replace (but still cheaper than buying a new motor)!

Steve checked the wiring earlier, I believe Tom said at the wiring harness, and didn’t see problems with connections there. Now Tom has been looking at diagrams for the control box and thinking he may try opening that up to have a peek. I imagine he’ll also be carefully inspecting the ground wire, thanks for that suggestion, Ron.

So... maybe it’s resolved, maybe not, and we’re not counting on it. Being some sort of mechanical problem, though, we will eventually get to the bottom of it. And it could be just the wiring, which would be so great!
- Rene

[dogon dory]

Sorry, Folks - Post Deleted By Author

[C-WEED]

Dan, I know what your saying. I like to think of it as a little TLC. You take care of it and it will take care of you. (hopefully)

[Falco]

Primative:

I scanned all these posts and they caught my eye. I have a 2004 22' with twin 40 Suzis - the first the factory ever installed on a 22. I love my twins but they are heavy and the ass end of my boat was constantly down (and the bow banging) until I finally learned the factory had installed the wrong sized trim tabs (too small). Once corrected, all has been well. In the interim however, the factory installed 5 degree wedges on the engines to position the props further under the boat, reasoning this would get the bow down (along with the too small trim tabs). This worked reasonably well -- except that periodically at 4800 RPMs one or the other Suzi would overheat, the alarm would go off and the engine would auto power down to an idle. This problem was very difficult to consistently reproduce. Looking over the transom at the engines while underway however it seemed to me that the side cooling water intakes (located under the cavitation plate) were subject to exposure (i.e., coming out of the water and thus not sucking any water in). This is made worse by the fact (contrary to factory advertising and popular belief) that C-dorys have displacement, not planing hulls. When underway a huge and very deep "hole" exists in the water just aft of the transom.

We took the wedges off, installed the right sized trim tabs and I've never had another problem. NOTE: these engines recover VERY quickly from an overheat. I suspect yours does too. The alarm would cut out within seconds of the engine assuming an idle and I could power back up immediately. Note also outboards will overheat VERY quickly and are pretty particular about the volume of cooling water they need.

So I hate to send you on a wild goose chase, but I would look very carefully at your engine mounting (especially position of the cooling water intakes at speed) and/or engine trim (and/or trim tab position if you have them) when this is occuring. Perhaps try different engine trim positions to see if you can replicate the problem (or not). My best guess would be to try and position the intakes "deeper" (add weight aft or refit the engine on the transom?) and/or further back (i.e., higher trim) to avoid the "displacement hull hole".

Good luck. Engine overheating is about the worst thing that can happen to an outboard. Hope you are changing your oil often.

Falco
Bucking Coho

[Sea Wolf]

Falco-

Thanks for the very through explanation of the problem you faced! Amazing how the factory trim tab set up was done in wrongly and how hard it was to find and correct the problem.

The great service this site provides is to share these ideas so that others don't have to work through their problems alone. I wonder if the factory always shares these revelations of wrongs with the other boat owners who they know are in similar situations?

I am in disagreement with you on the planning/displacement nature of the C-Dory. I do believe the boat fully planes, and begins to do so very early in terms of mph, gradually working through some transitional stages from about 9-12 mph and even further before it gets on a full, hard, flat out plane.

At these lower speeds, semi-displacement movement takes place, with the water leaving the hull in an upward movement behind the edge of the bottom/transom joint. The shape of this water flow will be dependent on the boat speed, loading (weight) in the boat, and as well the trim of the engines and even the trim tabs.

In my opinion, it would definitely be possible for twin motors mounted off-center (as they must be) and tilted forward up toward the bottom of the hull to take in air in the space behind the trailing edge of the hull and the rising wave form, and probably only at certain speeds and conditions. One definitely has to consider that they are pulling water down to them under these "tilted up" circumstances and could well pull down air as well.

Tilting the motors back into a more horizontal trim following the trim tab replacement would account for the termination of this problem.

Since this pretty much reasoned speculation, not direct observations, I guess we'd have to hang someone over the back of the transom as an observer with the original set up to get some verification.

Maybe if we find the guy in the in the kayak who stole Tyboo's sturgeon we could put him in the plug cut sea lion outfit and "volunteer" him to be the observer/bait and go whale watching. Joe.