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enlarging pee hole ??

crankbait

crankbait

Regular Contributor
I have a 90, 175 hp evinrude, that got to close to some mud sand bars on the last outing. I flushed the engine and and ran it on the muffs until I thought the problem was solved. on the last outing......the pee stream was plugged again at the restrictor. I opened the clog and ran the motor into the dock with the small hose removed from the restrictor.

my question is......can I open the orifice of this restrictor to increase the pee stream ? the reason why I ask this, is the motor came off a bass boat that had a pressure gage in the dash that teed off a fitting on the pee stream hose. with the restrictor removed, the stream is as strong as my Yamaha 9.9.
 
it gets in internally through the routing of the water. It is not a simple system like an automobile engine. the main immediate reason was given above. (your gonna get back pressure to water pressure and overheat that water and restrict its design to flow out of the motor at a specific volume/capacity.)
additionally...
If you take an outboard apart you will be amazed at all the cooling system does. Multiple functions, such as preheats the cold intake water as it fills up in the side chamber heat plate and covers. (pull one off and you will see that it looks like a rats maze, heats water first, then sends it to cylinder walls next then goes to the hottest area next which is the top of the cylinders where the combustion chamber lies. in between these systems it has openings directly into the beginning of the exhaust ports of the cylinders, cools it and washes the partially burnt wasted and not fully used 2 cycle oil and gas mixture, so it can run down through the skeg and out the prop. so there are direct areas , lets say connections from pressurized water cooling systems directly to the pressure of the exhaust, so if the motor cannot keep up its water pressure because you are allowing too much to escape from an unchocked pee hole than the exhaust pressure backs up to the water system and heats the motor more so and if worse will stop the water flow through parts of the system and be overheating, but you will still have a pee stream etc etc. it also will clog up your engine at low throttle or trolling speed. If the water system does not rinse the throat of the exhaust and wasted evacuation system the slowly moving waste makes a thick milky mixture that hangs through your cooling system, (when fresh and wet if you pull the lower unit down it will look like someone dumped a milkshake up in there. this dries turns to powder clogs bunches up and hardens and will clog the smaller ports in cooling system first. and the smallest orofices happen to be at the combustion chamber (a.k.a the hottest part of your engine. when you pull your mot/boat out of the water this milky plaster crap clogs most of the motors drain holes, and backs down to the top of the water inlet tube, and restricts it like a clogged artery of a human heart.
summary these water systems are not a bolt on after thought water system designed to push a lil water in and out of your motor. they are complicated with interconnected function and purpose, and have been developed and refined for over 75 years. If one would think that these big manufacturers would unnecessarile choke down the pee hole because they are too cheap to ream out a piece of plastic ,, one should think again. s
bill_w said:
How is the exhaust gas gonna get into the cooling water? From where?
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It dont work like this fella's as if so a weak water pump would allow the same thing. The indicator comes off exhaust water jacket and it is just a indicator it has nothing to do with cooling. You can enlarge pee hole hose up to 1/4-5/16 dia with no problems other than it wont spray as far.....
 
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That is correct "A WEAK WATER PUMP WOULD ALLOW THE SAME THING",,,SO WHAT's YOUR POINT???????. Are you saying that it is ok to run around with a weak water pump on an outboard motor and none of the above will happen. ?

Alos
-you say the pee hole indicator has nothing to do with cooling. Well what the heck is it indicating then ??. That is like saying an oil pressure gague has nothing to do with the lubrication system of a 4 cycle engine.
-also you say the pee hole water comes off the exhaust manifold jacket. I have never worked on an "OUTBOARD" where that is true,
every one i have been into the pee hole is at the top of the engine or close to it, think I had one where it was at a lower cylinder for some reason, but the pee hole source was at the very end of the cooling system water run, and the next and only thing after that was a small drain hole, always real small, bout the size of a #41 choke.
 
b521, you've lost me with your explanation. On all of the bigger OMC's I own (3 V4's, 3 V6's, and a V8) all of the telltales come directly off the exhaust water jacket. And I've had many of my outboards torn down, and I can't think of any where the exhaust and cooling water interact, except in the midsection housing. This includes my old motors, 5 1958's, 2 1964's, and a 1972, all twins, 5 1/2 to 50 hp. The tell tale outlet on my 200 hp looper is at least the same diameter as the hose that goes to it, if not bigger.

All the indicator tells you on these motors (V4 and up) is that the impeller is actually pumping water. It's not telling you that the water is circulating through the block in any way.
 
"A WEAK WATER PUMP WOULD ALLOW THE SAME THING",,,SO WHAT's YOUR POINT???????.
Point is exhaust gas cannot enter cooling system as was stated as exhaust pressure would overcome a weak impeller..
-you say the pee hole indicator has nothing to do with cooling. Well what the heck is it indicating then ??. That is like saying an oil pressure gague has nothing to do with the lubrication system of a 4 cycle engine.
-also you say the pee hole water comes off the exhaust manifold jacket. I have never worked on an "OUTBOARD" where that is true
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The indicator on a Johnrude is a indicator that impeller is working, it can be peeing fine and still overheat. The V-4/6 crossflows and all the Merc inline motors use the water jacket for the indicator stream as it the first to fill up.
When you suck sand/mud into the engine is it OK to make the telltale larger so it don`t plug up so easy?
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Yes....
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Kimcrwbr1
first you say the following
kimcrwbr1 said:
My concern would be when running WOT. When the thermostat opens up running the engine hard is there going to be enough water going through the heads. The water pressure needs to be higher than the exhaust pressure or the exhaust gasses will enter the water jacket and not cool properly. You can try just keep a close eye on head temps and that it dont lose pee pressure running the engine hard.
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Then you say this
When you suck sand/mud into the engine is it OK to make the telltale larger so it don`t plug up so easy?

summary is: you say don't do it (as in don't enlarge the pee hole) as you will lower water pressure, causing exhaust gasses to backfeed into the watersystem causing improper cooling, then you go the other way and say it is ok to open it up to keep it from clogging.

could you explain these opposing answers to the same question.? I believe the question is it OK to enlarge the pee hole restriction, meaning did the manufacturers choke it down permanently for a reason or not???
 
faztbullet
you state the following
Point is exhaust gas cannot enter cooling system as was stated as exhaust pressure would overcome a weak impeller..

well if the exhaust pressure beats out the water pressure (which you just said and which it does do) then it will indeed backfeed.
 
The point is your incorrect as enlargeing pee hose has nothing to do with back pressure or cooling operation of motor. What I said was if it worked by your theory the exhaust would overcome a weak impeller (which it wont)...
 
It is not just my theory. Look at posts number #2, #3, and #5. all seem to agree, but your theory is different.
And every manufacture out there chokes down the pee hole size from the I.D. of the direct hose that feeds it. IMHO. I cannot see how anyone could consider that a coincidence, rather than it being part of the design. and you don't have to choke it down to see a spray, that is not why it is choked .. unchoked the spray has a lot more volume to it which reduces the cooling system "pressure" thus not allowing the cooling water to escape from the designed openings with as much force and pressure to do its job. out it's system through to meet with the exhaust in the midsection/adapter plate area.
faztbullet said:
The point is your incorrect as enlargeing pee hose has nothing to do with back pressure or cooling operation of motor. What I said was if it worked by your theory the exhaust would overcome a weak impeller (which it wont)...
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that is correct .. the exception is in the mid-section housing, on smaller outboards it is right at/below the adaptor plate.
b521 said:
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bill_w said:
b521, you've lost me with your explanation. On all of the bigger OMC's I own (3 V4's, 3 V6's, and a V8) all of the telltales come directly off the exhaust water jacket. And I've had many of my outboards torn down, and I can't think of any where the exhaust and cooling water interact, except in the midsection housing. This includes my old motors, 5 1958's, 2 1964's, and a 1972, all twins, 5 1/2 to 50 hp. The tell tale outlet on my 200 hp looper is at least the same diameter as the hose that goes to it, if not bigger.

All the indicator tells you on these motors (V4 and up) is that the impeller is actually pumping water. It's not telling you that the water is circulating through the block in any way.
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well all the other ones do, so how does that work. In other words a gazillion do and a couple do not.
My guess is they have more flow thereby being able to keep wih maintaining the pressure they need to work effectively in all they do.
With outboards there will always be a few exceptions.
This discussion is predicated upon too much pressure/ flow being relieved by cutting of the restrictor. (kinda like washing your car without a hose nozzel) that is just a side analagy. and the opposing stance is that exhaust flow/pressure will not affect water flow/pressure.

Now keep that in mind and tell me why there are a gazillion threads in here, stating that they will get a pee stream at idle, but loose it when they increase the throttle. Because you are increasing the amount of exhaust in relation to a small impeller that is also increasing in volume, but not enough because there is a problem. If exhaust pressure did not enter into it the thing should still pee. . The statement that exhaust that exhaust in most all outboards is seperate and unaffected by the exhaust is false.

Thats one of many ways I see it work.


racerone said:
?????------------The 2 cylinder 48 / 50 hp models do not use the restricter nipple.---So how does that work ?
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I'm thru with this post as its obvious you have read one to many Selco manuals and do not fully understand how a t-stat controled cooling system works (Educated beyond one's intelligence) . As for the original posters question ..the answer is yes you can enlarge it and it will have no effect on cooling system operation.
 
no problem
but your statement of educated beyond ones intelligence, np if I were going to back at ya I would say, you can't argue with someone dumber than yourself"
faztbullet said:
I'm thru with this post as its obvious you have read one to many Selco manuals and do not fully understand how a t-stat controled cooling system works (Educated beyond one's intelligence) . As for the original posters question ..the answer is yes you can enlarge it and it will have no effect on cooling system operation.
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Racerone

You ask good questions that are relevant. Not scewed.
Just thought of something to mention as I am pretty sure you have been into them. The Merc 110’s with the nylon washer /bushing which is at the top of the water intake copper tube. It melts, from heat, . I don’t believe it it melts from the heat of the block. IMO that block would seize way before that bushing melted. Just an opinion ..Why, the reason I am presenting this to you is because it is at the beginning of the cooling water, cooling process of the power head. There by eliminating confusion with dual purpose applications in the water systems routing down the line. ) If you remember after the water passes through that bushing it travels to two places along a horizontal milled slot. First exit of maybe mmm 70 percent of its capacity the water goes up to the side cover distribution rats maze. The remaining water travels the width of the adapter plate along a milled out slot that is protected from the engine as it is covered by a gasket on its top side. That water cools the adapter plate primarily, (as the adapter plate bears the initial/highest heat from the exhaust) especially in the bushing area. (as bushing is connected to adapter plate , which holds the prescious bushing(to cool it) then down a dump sliding board tunnel then shoots out directly to the hottest part of the exhaust and they all mix and fight pressures. . That water from there (the 30 percent )
)never enters the powerhead and it has a direct unrestricted exit pathway to the exhaust pressures. That area is real hot, under load it is extremely hot. I believe when engines melt that bushing it is melting primarily from the heat of the exhaust (heatgun), not so much the powerhead. Now that is only one place the flow pressurized cooling water escapes from along its long double run and capacity reservoir build ups along the side of the inspection cover plate which internally routs different waters from different pre heated areas to its respective purpose, (some to cylinders, some to heads, etc etc and within all that the system looses slight pressure because there are ported holes in other areas through all the flat points that are for drainage when the motor shuts off. And yes those drain holes are open areas where if there is “not” a lot of water pressure then the hot pressurized gasses come in.
So there is many areas that exhaust is able to fight with water pressure that is weaker than designed. So if you cut its nozzle off to wash your car, there by now running your garden hose at full port,,, hope nobody is runnin the shower and flushing the commode at the same time.
Not trying to be funny a trying to be relative
The whole thing can be summed up with one word, CAPACITY
 
I have replaced many of those melted bushings due to the block overheating.-----------------As for the rest of the rambling I would like to know what you are consuming as I think I should try some .-----Over and out.
 
A 110 does not have a t-stat controled system and cooling is controlled by water restriction in block like all inline crossflow Mercs from 9.8(110) to 150hp I6..
 
Agreed and thats the whole point. . Cooling is controlled by water restriction.
faztbullet said:
A 110 does not have a t-stat controled system and cooling is controlled by water restriction in block like all inline crossflow Mercs from 9.8(110) to 150hp I6..
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