73 Evinrude 65hp Triumph Thermo-Switch unhooked

[wkuadam07]

I bought this awsome pontoon yesterday!!! It has a good ole 65 triumph circa 1973. Model 65373R. Drained and flushed the carb bowls, changed the lower unit oil. Fresh gas can from my other boat. Started it and it runs great! Compression tested it after running it and it's 118, 118 and 115 on the bottom. It did stay cool, i plan to do the thermostat and a water pump impeller, ordered the parts on Iboats today as a matter of fact. I took it for a good long cruise with 6 friends and did periodic checks to make sure it didn't feel or smell hot and it's running quite well. It needed a rectifier, had bummed wires on the back and had obviously been cracked from time and then touched and got hot, tested and no luck on charging, so I substituted a 4 wire rectifier from a newer model i had laying around and left 1 wire unhooked and it charges perfectly now. I did check the stator and it checked to the spec i could find, at least both wires had the same resistance, and with throttle the stator made 30-40 volts AC, so i think my rectifier swap is the fix there, at least temporarily. I have wrangled these charging systems before.

Here is where my problem lies, the wires coming from the head, i believe it's where the "thermo switch" pn 384088 is located were unhooked when i bought the motor. Does anyone know how this thermo switch works on this motor? Normally open, normally closed, does it work on a change in resistance? I am assuming that these 2 wires hook to the power pack, but the labeling isn't adequate enough to hook it up being certain that i am not going to fry something. I want to test this switch, and hook it up properly if it works, or replace it if it doesn't, but i am not sure how to test it. I looked in the sticky thread at the top and wasn't able to locate wiring diagrams... I am fairly handy with my volt meter, and basic knowledge got my this far... but sometimes it isn't enough and I must bow to the experts... and beg for your help. I would love to have this motor working 100% so i can have piece of mind this summer and have good times at the lake, as is, it could overheat and i would never know until it was WAY too late...


Many thanks in advance.

Adam

 

[F_R]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

I gotta run, but just a quick reply.....Are you talking about the switch in the cylinder head or the one in the exhaust cover? The one in the cylinder head is to turn on the overheat horn if it gets hot. It is a normally open switch, closing at a certain temp to sound the horn. The other switch is for the semi-automatic choke. Many of those are disconnected on purpose.

Neither one connects to the power pack in any way at all.

 

[racerone]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

This is how it was designed.----Thermo switch for engine overheat sounds the horn.-It has a tan coloured wire.---It goes to ground when motor runs too hot.-------Test horn by turning switch on and grounding at the rubber covered connector.-----Thermo-electric choke switch is lower on the cylinder head.---Cold motor and turn ignition switch on and choke goes on half way.--Operate manual choke switch for full choke.----When motor starts it will run with partial choke. When it reaches operating temperature the choke kicks off.---Most of these thermo-electric chokes were reconnected to just work off the manual switch.-----Neither switch is hooked up to the powerpack.

 

[boobie]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

If the choke works properly just leave them unhooked. It was a bad idea anyway.

 

[oldboat1]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

I have a slightly smudged diagram for a '72 65, and think I either had or fooled around with the '72 model -- engine side shows a tan wire from the temp sending unit, with a knife disconnect in that wire, which runs through the plug to the overheat horn on the boat side. The thermo switch shows a purple wire to #6 on the terminal block, and a grey and yellow wire to #8 on the block. The purple wire proceeds on the boat side to one of the poles of the choke switch, and finally on to the second pole of the horn. The grey and yellow wire continues to one side of the choke solenoid (motor side). The other post of the solenoid (purple and red wire, #7 on the terminal block) proceeds up to the other post of the choke switch (boat side). It looks like the thermo switch is in the closed position when the choke switch is open (which might be the opposite of the choke solenoid -- can't tell).

But it looks to me like the horn might not sound unless both the sending unit, thermo switch and choke solenoid are properly connected -- seems necessary to complete the circuit.

not sure what wires you have in front of you -- but clearly there is no circuitry (on the '72 model) between thermo switch/switch solenoid or temp sender to the powerpack. As to concern over whether the overheat horn would properly sound, though, it looks to me like you may need to rewire one side of the horn if that automatic choke system is disconnected -- may need to override and replace the connection provided by the auto choke connection. Maybe that was already done, if needed, by the PO.

Anyway, not expert opinion by any means. But think your overall goal is to make sure the temp warning system is working -- hope all the stuff I've mentioned is irrelevant or easily explained away for operation of the warning system.

 

[F_R]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

OK, to settle this (hopefully). Here is the wiring diagram

 

[oldboat1]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

Thanks, F_R. So need to locate purple and yellow wire from the thermo switch on the '73, and move it to #7 to keep the warning system working -- yes? Simple fix, if hasn't already been done.

 

[F_R]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

No, not exactly. You move the purple/yellow wire from the CHOKE SOLENOID to #7, not the one from the thermo switch. Having said that, it is a modification to the choke operation, not to the warning system. Here's the deal: As originally produced, the electric choke was a two-stage affair. As soon as you turn on the key (cold motor) the thermo switch would half close the choke. The driver then lifts the toggle switch below the key switch and holds it while turning the key to start the motor. That, and the thermo switch half-close feature combined fully closes the choke for cold start-up. Releasing the key to run position, allows the choke to return to half-choke position till the engine warms up enough to run without some choke. When the engine is warm enough, the thermo switch opens and the choke opens and stays open till the next cold start-up.

Got it that far? Here is the rest of the story. The scheme worked just fine....except. In some situations, the half-choke would be on when it really didn't need to be, usually after shutting the motor down under certain conditions, and restarting. So, the company sent out a service bulletin advising the re-wiring to prevent the problem. After the modification, the driver holds the toggle up to choke it and releases it to run. There is no longer any warm-up choke feature. If the motor sneezes and tries to stall before warmed up, the driver momentarily lifts the toggle to give it a short shot of choke. That's the way many motors still are today.

The overheated motor warning horn is a totally different circuit, with a tan wire from a different thermo switch.

Are we clear now?

 

[oldboat1]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

good diagram. May help the poster identify the protruding wires.

 

[wkuadam07]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

You guys are awsome!!! That diagram did help. What is disconnected on my motor is the automatic choke temp switch. The other temp switch is hooked up still. I agree, that automatic choke is a bad idea waiting to happen, my motor starts excellent if i simply turn the key, if it doesn't hit i bump the choke till it hits, then bump the choke again if it tries to die. After 10-15 seconds it runs perfectly like this. After it's warm no choke is needed at all for a quick start. I am still going to go home tonight and check the high temp horn circuit, if it's good to go then i have a solid motor. My iboats order with a water pump impeller, spark plugs a plenty, a new thermostat kit, and some other goodies is on the way.

The only other worrisome thing about this motor is that it doesn't have a tell tale line up high to confirm water pressure. My other evinrudes have a tell tale that sprays out the bottom half of the engine cowl... is there a place to tap this motor and add one? Or am i looking in the wrong place for the spray line, perhaps it's stopped up, and i have not located it.

Many thanks!!!

 

[F_R]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

It doesn't have a tell-tale

 

[racerone]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

If you maintain the water pump impeller ( replace every 3 years ) you really do not need a tell tale.---Tested hot horn is all you need.

 

[oldboat1]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

Yeah, if you continue along with the maintenance stuff you are doing, you will be fine -- impeller replacement, check out and test warning system. Tell tales are OK, mostly at startup IMO. But in case of catastrophic failure of the cooling system, I can't see where the motor gets saved. By the time your son or daughter taps you on the shoulder and asks whether there should be water coming out somewhere (and btw, it's getting kind of smoky), the motor is probably cooked.

 

[F_R]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

Personally, when I'm out boating, I find a lot better stuff to look at than watching a motor pee.

 

[racerone]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

If you have a motor with a tell tale you still need to learn to interpret what it is " telling " you.-----Many motors with this tell tale have been overheated by owners who simply did not know.

 

[wkuadam07]

Re: 73 Evinrude 65hp Triumph Thermo-Switch unhooked

^^True story there, i watched a guy "warm his motor up" with it latched up and completely out of the water one day at the river. It died, he lowered it, he shoved off, and when he tried to restart it had boiled the gas in the carbs and the hood was full of fumes... the starter made just enough spark to ignite and the cowl went to confetti... and he was floating down the river only 3-400 yards from a dam. He ruined a nice looking old merc that day... I towed him back to the ramp so that he wouldn't be on the evening news.