Thermostat or impeller?

Hey all, I've searched on here and came up with a couple of different answers already, but I thought that I would put the question in my own words and make sure that I still get the same results.
1978 Evinrude, 70horse triple cyl.
Just got it, but this is my second OMC o/b. Normally I'm an I/O guy.... but the money was right.

Anyway, my question.

Just below where the cowl sits on the motor there are two "pig nostrils" that I remember being the pee holes on my 85hp Johnson V-4. I remember seeing water puking out of them while being towed on a tube and having that sense of relief to see that much water coming out of them.
I just got this 70hp and upon putting muffs on it and starting it I am not seeing water coming out of the two holes. NOW question is, do I have to wait for the thermostat to open for a significant amount of water to come out of them? OR is my impeller pooched?
I haven't had it on the water yet to run it long enough to see it get up to operating temp and see if the water comes out of the holes.
Thanks for any input.
Chris

Re: Thermostat or impeller?

In my opinion, I would take the lower unit off, and inspect the impeller anyway. You never know what the previous owner did, or did not do. If the impeller looks like it is scratched or if it doesn't bend outward like a star in all directions when you remove it then I would replace it anyway. Also, check out the impeller housing, and feel for any gouges or cuts in the metal.

As for the thermostats, I would replace them too. I like to write down what I've done to an engine after I do it, so that I can remember years down the road what and when I did it.

Re: Thermostat or impeller?

I agree with luckyinkentucky. Check it out. Also your not going to get the water pressure from muffs like you will running it in a barrel or in the water. One more thing if you run it on muffs or a barrel don't do it WOT.

Re: Thermostat or impeller?

Either I am confused or you are.

I had a '75 70 Rude which I bought from a friend who had it for 10 years. He said it was hot. As it turned out, it was hot, alright, but not because it came off the assy line with excessive horsepower.

Over time it would start and run initially very smoothly but then as it continued to run it ran rougher and rougher. Finally one day, at WOT the engine froze. In retrospect the reason was a stuck shut thermostat which apparently had been sticking, and finally just froze. Cost me a .030 overbore overhaul.

The engine had no pee tube and no warning horn. After the overhaul I bored and tapped a hole in the head water jacket cover and bored a clearance hole in the lower right rear cowl installing a 1/4 pipe/5/16" hose barb and hose to the outside. I think I just left the stat out but don't remember. Had a good stream so I must have just left the stat out.............so it couldn't freeze on me again. Ha!

The holes (pigsnouts) at the rear of your engine that you refer to are exhaust pressure relief holes (some round some rectangular on OMC of the era) primarily intended to relieve combustion gas pressure at idle and low speeds so that they don't have to come up from under the water which poses significant back pressure on the engine trying to run. At WOT water may flow out of them quite freely but it is not a requirement. They are not a pee tube.

had a '72 125 Johnny, which I used to ski behind and water flowed freely out of them while I was being towed. Don't recall any at idle.....may have been some sputtering mist. All it said was that it was easier for some of the WOT water volume to exit those holes rather than go down and thru the hub to exit.

I don't know if your stat has to be open for water to exit there or not. The exhaust cooling is a separate loop and is not thermostatically controlled. It can't be. The exhaust manifold cover has to be cooled as long as the engine is running or you will burn it up. Some of the water coming out of the holes mentioned is obviously from cooling the head of the engine (via the stat) but how much is from where I don't know and it doesn't matter.

Not sure I agree on low pressure from ear muffs. Your city water supply is putting out like 70 psig and with the hose putting out full volume, water shoots out the side of the muffs till the engine starts and then is consumed proportionally to the speed of the impeller. Usually there is still some water excaping around them even at moderate rpm's indicating that the city water supply is supplying more water than the engine needs. Other than goosing for an instant, I never ran an engine at WOT on them.

On running WOT on muffs, the only problems I would have with it is the fact that the lower unit has no cooling unless muff bypass water is flowing over it and with no resistance for the prop to turn against, overrevving would be eminent. Uncooled, that gearbox can get hot and you can damage your seals. Also, even in gear, there is no back pressure on the engine's drive train like you would have with the prop turning against the water and it would be possible to throw a rod or something like that from over revving.

My 2c

Mark

Re: Thermostat or impeller?

Mark, thanks for the answer, it is appreciated. As far as the other two comments, yes, I do plan to pull the lower unit off, but that wasn't the question. I'm new to this forum but not new to forums and it's nice when someone like Texasmark actually READS the question and then answers properly.

Don't get me wrong Nimmor and Lucky, I appreciate your input, but two answers in a row stating the exact same thing that aren't even an answer are just a waste of time and effort and bandwidth.

Mark, you stated the same thing as I about being pulled and seeing lots of water coming out, but not so much at idle, and that's all I needed to know. We want to get out on the water today and I didn't want to pull it to the ramp without that answered. Thanks again.

I am not bashing the other guys, like I said, I do appreciate the input ( I had planned to do that on Tuesday).
Thanks for having me on the forum.
Chris

Re: Thermostat or impeller?

If you have no water at all coming out , your pump is pooched . I wouldn't even start it again until I pulled the foot and checked it out . Unless the pee tubes are clogged . I had to clean Dirt Dobber packing out of mine one time this year . It's amazing how small of a hole those suckers will fill with dirt .

Re: Thermostat or impeller?

Ok Monkaroo, can you please tell me where the pee holes are then? I don't want to cook the motor, but at the same time I think that I am worrying about nothing. I did pull a bit of dirt out of one of the holes that was packed up with wasp mud.
These are the pigsnout holes. Are they supposed to have water come out at all times? I thought that they were the exhaust relief holes.


A steady pee stream comes out of this hole just above the horizontal plate on the forward portion of the leg that gets warmer as the engine runs,


Other than that, there are no other spots that would be visible above the water line that would be a pee hole.
Thanks
Chris

Re: Thermostat or impeller?

I think they started putting tell-tales on in '79. My guess is that you don't have one. You can check the exhaust cover for a fitting and a tube. If you find it, follow the tube out to a nipple. That's your tell-tale out. It's not uncommon to have to shove a wire up there to clean it out every now and again.

If you don't have one, you can always retrofit one in if that's your desire.

Re: Thermostat or impeller?

Those holes are bypass ports and water will not pour out of them but rather a fine mist occurs at idle. These ports exist because of back pressue on the underwater (through hub) exhaust. At speed the majority of the cooling water exits the engine through the hub. If there is no water at all coming out of those ports, its water pump time. On a new to you engine, thermostat, bypass valve and impeller replacement are highly recommended. Since the engine doesn't have a tell tale, you can add one. Search this forum for the service bulletin.

Re: Thermostat or impeller?

Thanks very much guys.
Very informative, and I appreciate that.
I planned to do the impeller after the weekend anyway, but just don't have the time today or tomorrow and wanted to get out a little bit.

Thanks again for answering my questions.

Chris