Sudden power loss with prop. or something else??

primative":34nxmr9t said:
top cylinder with infrared type point and read gun with temperatures from 202 to 214, but mostly 202 at top and 165 to 175 at bottom.
Click to expand...

That sounds like too much variation to me, I bet there is a simple obstruction of some kind; in the coolant-suply pipe (from the waterpump housing) maybe? like a improperly aligned rubber seal, or o-ring? It just sounds way too much like your not building enough flow in the cooling system :!:
Was any of this going on, before the first impeller change?

Was a little difficult following this thread precisely :disgust
 
Hey Red Fox ! Your ears may have been burning over the last week. Your name and some of your photos were discussed during the Nashville Gathering cruise on the upper portions of the Cumberland River System in TN. We got to see a few eagles flying around and checking out our C-Dorys as we made passage up river. New birds to our area and the last time I saw eagles in the wild was the inter passage cruise in your neck of the woods. Wish you could have made the trip Brother! Later
 
Yeah but were there any gorgeous eligible young ladies for me ... :smilep :xlol Thanx for the notice my friend :thup Can't wait till I get the new Canon 20-D ... waiting :cry

Now, back to the subject here :shock: :D I was also wondering about that water in the 'river' you (CAVU) (if yet talkin to me, that is :| ) run in. Is it possible that there is a problem with deposit build-up from its water? It does sound like 'overheating' is going on :!: and there is simply an obstruction or leak in the plumbing :?
 
Dan,

I think you are right. This sounds like an electrical/electronic problem. My guess is that it is in the main ignition control box or the wiring to it. That is why you occasionally see the tach way off and why this is so intermittent.

When I was working as a mechanic we had a customer bring in his '73 Mercedes 450SL because it was "acting wierd". In reallity what it was doing was any time you put it in drive and hit a certain RPM the engine would die. Then when it slowed down again it would fire back up. You could drive it at any RPM in reverse though! After many arguments with my boss and many hours of replacing uneeded parts I finally tracked the problem down to a broken wire going to the computer. What was happening was that when the engine RPM's came up the motor moved a little bit causing the wire to lose connection. As soon as the motor shifted back it started running again. I spent well over 40 hours and 5 weeks trying to find this problem as the customer was insistent that we take the time to fix it regardless of what it cost.

To me what you are describing sounds very much like what I had with the 450SL. What I would do is unplug and replug all electrical connections going to the ignition control box. If you find one that looks like it was making a bad connection fix it. If after doing that it still has a problem see if you can find an accomodating person with the same motor as you. Borrow their control box and do a test run. It the problem goes away you have found the problem!

Good luck! These kinds of problems are why I'm bald now! :lol:
 
I think electrical is the most likely source of the problem. A key element is the ground side of the circuit. Grounds which change in resistance because they are loose or corroded will change the voltage from a sensor and cause it to read a false positive.

I 1991 Ford Powerstroke that ate about 3 to 5 glow plugs a year. A month before I sold it, I found the problem was a ground wire to the block had a higher than anticipated resistance. The glow plug controller interpreted this a condition that told it to leave the glow plugs on longer than necessary causing them to burn out at a higher than expected rate. All becasue of a few ohms.
 
I think Dan is on the right track. Not knowing a thing about Hondas, I would think a black box is generating the tach signal. The brain senses an overspeed and cuts rpm down. Operator throttles back. Brain senses this and allows rpm to build again as throttle is rolled on. Could be the temp light is another function of the black box? Both over temp and over rev are safety features probably monitored by one box.

The Tach is showing eroniousely high RPM's at times and engine doesn't cut out. Then the opposite happens. Engine is within rpm limit and overspeed cuts in... Find out what electrical gadget deals with both. If it uses a simple sensor under the flywheel or camshaft to sense the rpm check that, too. Possibly dirty from mud-dawber or damaged.
 
LOL I have to agree, after re-reading a little more careful here :crook . But the large temp-variation in the head? taken does not sound normal to me. Could be both, and it comes to a process of elimination, whats another theory going to hurt :idea: :wink:
 
Hey guys, sorry for the slow response to your replies. I'm illigiterate,and am not too skilletful on the gillternet. I know these are excuses which is a cunning invasion of the facts. So I will try not to be funkey any more, and here it is.

I feel a little giddy.Since I replaced the thermostat I've been out four times without a problem. After reading your responses, I realize it may be a false coincidence, and logically this problem is not likely solved. But if it is that would be ok by me! My wife has intuitively felt it's an electrical problem all along. That doesn't mean anything yet, but we all know its a bad sign.

For what its worth I put the old thermostat in hot water with a cooking/mercury thermometer so I could see when it started to open. I think it started about 172 degrees and was as open as it was going to get at 176-178(I don't know what full open is supposed to look like).I had already installed the new one and didn't think to compare the two.


Looking to the electrical side of things is next. I will let you know what happens.

I really appreciate your responses. These ideas are just what I needed to be able to pursue this any further.

Thanks,
Tom
 
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.
 
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
 
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
 
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)
 
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
 
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.
 
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