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Discussion Starter · #1 ·
so, i finally got my outboard back together (thanks silverfish! it purrs like a kitten.). i cannibalized another lower unit with a better design and replaced all the seals and gaskets in the lower unit. i also replaced the impeller system. at idle, i get a weak stream of water, if any, from the telltale. at roughly 2k rpm (by ear), i get a fairly healthy stream from the telltale.

so, how do i know if i'm overheating? i don't want to have gone through all the trouble of fixing the lower unit to end up messing up the powerhead.
 

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One trick I can think of is a temp. crayon type thing (can't remeber what it was called). We used two of them. One melted at optimum running temp. and the other at a higher temp. You drew lines on the powerhead with the crayons and started up the motor. You wanted the one to melt and the other not to. Only problem is I don't know where you would get them. You might try a shop to see if they would mark the powerhead for you. Probably do it for free.
 

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Well, when it starts to lose power and seize up you'll know. Brutal, but true.
I'm assuming it's a small outboard without an audible overheat alarm. If it has a telltale, and there's water coming out, it ain't getting hot. If you stick your finger under the telltale water it should be warm, but not hot. If the motor has a thermostat, it will probably run a little hotter.
As long as you have that telltale water, I wouldn't worry about it.
 

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You were pretty close, STG. They're called temperature indicating crayons. They work just like you said.
Another thing are heat tabs used by engine rebuilders, but those only work at a high temp, and your motor would do a Chernobyl by the time one of those melted.
 

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As long as it aint clogged, run it. I don't know what you got, but it should pee pretty steady, even at low rpms. If you switched out the lower unit, did you get the correct impeller?

Good Luck.

Mark and the not so master mechanic dog.
 

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I occasionally see motors running hot while I'm in trolling mode. Telltale sign is alot of steam coming from the water outlet. Not trying to be "funny" here, but if your water is steaming alot..it's running too hot.

If you haven't got a manual for your motor, you can probably get one at GI Joes. Good thing to have if you do alot of your own work, and it looks like you do.

Mark
 

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Discussion Starter · #8 ·
a buddy of mine gave me the shop manual and i've also got the user's manual. neither of them tell me how i will know if it overheats, just what to do after it has overheated. i ran it in a trash can today and saw a lot of steam coming out of the exhaust after about 5 to 10 minutes or so. i didn't run it for long because the telltale wasn't very strong, except at higher RPMs. the user's manual says it has a thermostat but the shop manual doesn't show one in the engine diagram.

[ 04-27-2003, 03:25 PM: Message edited by: ampersat ]
 

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Discussion Starter · #9 ·
anybody else got any ideas?
 

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other than the usual, take the hose off where it comes out of the block and start the motor, if there is a big stream comming out your hose or nozzle is plugged, if it barely comes out hook the hose back up to the motor and remove the other end from the nozzle and blow some air thru it as a peice of junk could be caught in the tube on the inside of the motor, did you use dishwashing soap to lube your new impellar when you put it in ?, if not you might have fried it ?

[ 04-27-2003, 07:00 PM: Message edited by: boater ]
 

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My telltale doesn't pee all that much and mine has been running faithfully for years (I use it on my drift boat) Of course on the drift boat it doesn't run for long spells either.
 

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One time the telltale on my Merc was plugged up by spider eggs.
You'd think the water would have blown it clear, but I had to pull the hose off, run a wire thru it, then blow it out with compressed air.
The intakes on the lower unit get clogged up sometimes, too.
 

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My temp gauge is my hand. If I stick it in the stream and it is hot, problem, if not, all is well. :smile:

Course, many of the guys here could just see how hot their onboard sink is.... :rolleyes:
 

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Dear Ampersat:

I had this problem on my 7.5 Johnson for a few years. My motor would heat up and soon shut down; I could not restart it until it cooled.
Twice I took it to Stevens and they finally found corrision inside the motor on the aluminum.
Before this incident I would often find sea weed stuck in the line where the water exits the motor. I cleaned this line up with a thin copper wire.
Good luck & Best Fishes

Are you still thinking of a Tigard lunch or happy hour sometime?
 

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Get a temp guage and mesure the water comming out of the motor at idle, then measure the head temp, should be able to get a pretty good idea
 
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