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Two holes below the cowling

J

jnscherr

Contributing Member
I have a 1983 70hp Johnson. Wh

I have a 1983 70hp Johnson. What is supposed to come out of those two holes below the cowling?
 
"exhaust and wtr mist..the mid

"exhaust and wtr mist..the mid 80s would usually have a good wtr flow out of those,at high spd...those are....exhaust relief holes."
 
"I always though it was more l

"I always though it was more like chocolate milkshake, if you spray some powertune into the carbs with it running
"
 
You guys are hillarious...So i

You guys are hillarious...So it's normal for the exhaust and mist to come out those holes then. I thought with an exhaust through hub the exhaust all came out the hub. Maybe at higher speed then. Thanks again.
 
"(Exhaust Relief Ports - E

"(Exhaust Relief Ports - Exhaust Housing (Inner/Outer)
(J Reeves)

The long housing between the powerhead and the lower unit is called the exhaust housing. There is a inner housing within it that has a heavy duty seal around the bottom of it, or heavy duty seals around a inner extension between the housing and the lower unit.

The red hot exhaust travels down thru that inner tube and out the propeller with a somewhat supply of water to cool the propeller hub. A good amount of water surrounds and fills the space between the outer and inner tube, otherwise the outer housing would get so hot that the paint would burn off.

Some water pumps, for some reason (differing even when new) exert a great amount of water pressure, and if the exhaust housing seals are in perfect condition, the water fills the tube to a point of overflowing.

This brings into play those two holes or slots, whichever the engine might have, at the top rear portion of the exhaust housing just below the powerhead.

Now, if those two holes/slots weren't there, water would continue to flow up into the cylinders. Water not flowing out of those holes is no concern for alarm UNLESS that outer housing suddenly becomes extremely hot..... the warning horn should sound long before that happens.

The main reason for those holes being there (exhaust relief holes) is that when at an idle, there is an extreme amount of resistance encountered by the exhaust trying to escape due the fact that the outlet via the propeller is now blocked by a wall of water. The escape route in this case is for the exhaust to escape out those two holes, otherwise the engine would slow down quite quickly and die. If exhaust cannot escape, air/fuel cannot gain entrance to the engine.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"
 
Your 70hp utilises a thermosta

Your 70hp utilises a thermostat and a bypass valve to controll the water temp and water flow.
When the thermo opens you will see water which is hot exiting above the cav plate towards the rear section...At about a third throttle to half you will notice water exiting through the exhaust relief holes at the rear of the trunk housing just below the lower cowl
 
Now you have me confused. Is i

Now you have me confused. Is it water that's supposed to come out of there or exhaust?
 
"Both. Depending if the thermo

"Both. Depending if the thermostat and the relief valve is open, then both water and exhaust. At low idle You may notice water coming now and then as the thermostat operates."
 
"If water is comin out from th

"If water is comin out from the holes just above the cavitation plate at idle and the engine is not getting, only warm, would this indicate that water getting past the stat or relief valves - ie faulty parts or stat not seated correctly?"
 
O.k thanks. Everyhting is good

O.k thanks. Everyhting is good then. I think if there was something seriously wrong the motor wouldn't of ran as good as it did.
 
joereeves said:
"(Exhaust Relief Ports - E

"(Exhaust Relief Ports - Exhaust Housing (Inner/Outer)
(J Reeves)

The long housing between the powerhead and the lower unit is called the exhaust housing. There is a inner housing within it that has a heavy duty seal around the bottom of it, or heavy duty seals around a inner extension between the housing and the lower unit.

The red hot exhaust travels down thru that inner tube and out the propeller with a somewhat supply of water to cool the propeller hub. A good amount of water surrounds and fills the space between the outer and inner tube, otherwise the outer housing would get so hot that the paint would burn off.

Some water pumps, for some reason (differing even when new) exert a great amount of water pressure, and if the exhaust housing seals are in perfect condition, the water fills the tube to a point of overflowing.

This brings into play those two holes or slots, whichever the engine might have, at the top rear portion of the exhaust housing just below the powerhead.

Now, if those two holes/slots weren't there, water would continue to flow up into the cylinders. Water not flowing out of those holes is no concern for alarm UNLESS that outer housing suddenly becomes extremely hot..... the warning horn should sound long before that happens.

The main reason for those holes being there (exhaust relief holes) is that when at an idle, there is an extreme amount of resistance encountered by the exhaust trying to escape due the fact that the outlet via the propeller is now blocked by a wall of water. The escape route in this case is for the exhaust to escape out those two holes, otherwise the engine would slow down quite quickly and die. If exhaust cannot escape, air/fuel cannot gain entrance to the engine.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"
Click to expand...
 
joereeves said:
"(Exhaust Relief Ports - E

"(Exhaust Relief Ports - Exhaust Housing (Inner/Outer)
(J Reeves)

The long housing between the powerhead and the lower unit is called the exhaust housing. There is a inner housing within it that has a heavy duty seal around the bottom of it, or heavy duty seals around a inner extension between the housing and the lower unit.

The red hot exhaust travels down thru that inner tube and out the propeller with a somewhat supply of water to cool the propeller hub. A good amount of water surrounds and fills the space between the outer and inner tube, otherwise the outer housing would get so hot that the paint would burn off.

Some water pumps, for some reason (differing even when new) exert a great amount of water pressure, and if the exhaust housing seals are in perfect condition, the water fills the tube to a point of overflowing.

This brings into play those two holes or slots, whichever the engine might have, at the top rear portion of the exhaust housing just below the powerhead.

Now, if those two holes/slots weren't there, water would continue to flow up into the cylinders. Water not flowing out of those holes is no concern for alarm UNLESS that outer housing suddenly becomes extremely hot..... the warning horn should sound long before that happens.

The main reason for those holes being there (exhaust relief holes) is that when at an idle, there is an extreme amount of resistance encountered by the exhaust trying to escape due the fact that the outlet via the propeller is now blocked by a wall of water. The escape route in this case is for the exhaust to escape out those two holes, otherwise the engine would slow down quite quickly and die. If exhaust cannot escape, air/fuel cannot gain entrance to the engine.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store"
Click to expand...
How exactly the outer housing will get hot until the paint will burn off ? The housing is already inside the water, you have no clue what you are talking about.
 
vs565 said:
How exactly the outer housing will get hot until the paint will burn off ? The housing is already inside the water, you have no clue what you are talking about.
Click to expand...
That's alright little man... someday daddy might teach you how to read. My writeup is self explanatory. Here, let me explain it to you...... one short paragraph states "The red hot exhaust travels down thru that inner tube and out the propeller with a somewhat supply of water to cool the propeller hub. A good amount of water surrounds and fills the space between the outer and inner tube, otherwise the outer housing would get so hot that the paint would burn off."... The word "otherwise" indicates "If No Water Existed". Everybody else understands that BUT you Dumbass!
 
racerone said:
Really ??
Click to expand...
Yes Really racer! Years ago when you first came on Marine Engines site, you were loaded with sarcastic, snide, insulting remarks, casting such wording around to other members helpful replies as "Pure Rubbish" just to state one. I see that you haven changed. You just can't help yourself can you? For the record, I took a strong dislike towards you then when I was quite active... and now at the age of 91, due to your arrogant superiority attitude complex that's apparently embedded within your boney head... you can consider yourself a first class ass in my book!
 
joereeves said:
Yes Really racer! Years ago when you first came on Marine Engines site, you were loaded with sarcastic, snide, insulting remarks, casting such wording around to other members helpful replies as "Pure Rubbish" just to state one. I see that you haven changed. You just can't help yourself can you? For the record, I took a strong dislike towards you then when I was quite active... and now at the age of 91, due to your arrogant superiority attitude complex that's apparently embedded within your boney head... you can consider yourself a first class ass in my book!
Click to expand...
I don't think racer was talking you Joe.
 
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