15hp johnson 1975 impeller question

[Happyfingers]

Giday all

I have just finished installing a new impeller kit
this one

and i put the motor in a tank and it seems to be working though im still unsure if i did it correctly
water after 30 secs or so comes out of the little hole just below the engine, its not a real strong stream but it doesnt get hot, if i idle the engine for a long time the water flow seems to stop

when i installed the pump kit i didnt seal the gasket with anything (the metal plate) and im concerned that this is wrong
when i put the ears on the water intake before reconnecting the stem to the engine (just to see what would happen) the water seemed to squirt out from underneath the plate as if the seal wasnt all that good

are you supposed to seal the metal plate of the impeller housing with something ?

there also seems to be water coming out of the area where the engine pivots on the plate that mounts to the tinny, is this normal ?

if ive done it wrong i can just pull the engine apart again and do it correctly thats no problem it was reasonably easy to do

i was gonna get the engine serviced even though it seems to run quite well
but after the shop told me it was $279 for a service for a 15hp outboard i nearly choked the engine prolly isnt even worth that much

any help is much appreciated
the engine is pretty much the same as the one in the picture

 

[Happyfingers]

Re: 15hp johnson 1975 impeller question

i can get my 2009 model gtx 255 is limited and supercharged jetski serviced for $280

im mistified as to how it can cost that much for a simple service

 

[Numlaar]

Re: 15hp johnson 1975 impeller question

From my experience, it goes (from bottom to top):

Lower unit housing
Gasket
Metal plate
Gasket
Impeller housing

If there were no gaskets between the two sides of the plate there is nothing to seal it down, and nothing to prevent a loss of pressure to the outlet tube...

As for using an actual sealer, I have heard both pros and cons, I for one, did use a sealer on mine, (Permatex 2B - best gasket sealer ever made IMHO), and its sealed up tighter then a ducks behind hehe... (Keeping in mind thats only on FLAT gaskets, and not O-rings!)

I know kits vary, so thats just from my experience... someone else may chime in with more knowledge, but wanted to give you an answer

 

[Solittle]

Re: 15hp johnson 1975 impeller question

Gaskets are not needed. It is normal for water to come out of a number of places besides out of the center of the prop. There are at least one drain hole on the lower unit and quite OK for water to come out of other places.

With a fresh impeller you may get a flow of water out of the hole just below the hood release lock. The flow will increase with rpm and may become a steady, but not high pressure, flow. When underway at higher rpm water will come out of that hole with some force.

I have a 75 9.9 - same engine except for the carb.

 

[Happyfingers]

Re: 15hp johnson 1975 impeller question

ok cool that makes me feel better


but now i have pulled the engine apart i am more confused

i just stripped it down because i was reading some old post that said the bronse tube can fail to seat in the grommet properly

and sure enough that was the case
so im gonna retry that without that happening again

but what confuses me now is that when i pulled the stemm off again the rear cavity behind the impeller the walls of that cavity are covered in a milky type oil and water residue and i cant figure where it would be coming from

its not the residue of the oil in the fuel as it is quite significant
the residue wasnt there when i put the engine all back together

so common sense says it has to be coming from the gearbox which has had its oil newly replaced

i dont wanna run this engine in the bay until i have it right as my kids will be in the tinny

does anyone know what might be the cause of this residue
again its not in the front cavity that has the gear rod in it
its in the rear caivity behind the impeller housing
the walls are completely covered in milky residue

cheers
and thanks for the advice

 

[bktheking]

Re: 15hp johnson 1975 impeller question

This was my 76 15 the other day when I pulled the exhaust tube off the powerhead, look anything like yours? Note the water tube grommet is gonzo.

 

[Happyfingers]

Re: 15hp johnson 1975 impeller question

yes that what it looks like but its not in the exhaust

its in the cavity of the lower prop area of the stem (think thats what its called)

the engine seems to run like a charm, starts easy and idles great though may need some adjustment there

i just put it back together and i think i did a better job this time
though i suspect i will have to pull the gearbox out and im not confident as i have no idea what to do

also when i turn the throttle back to slow the engine stalls because the revs are to low, is this just an adjustment as when you put it in gear the throttle turns way past fast and the idle adjust screw on the side is screwed all the way in and is ineffective (doesnt do anything)

does gonzo mean stuffed ?

thanks for all advice

 

[bktheking]

Re: 15hp johnson 1975 impeller question

yes that what it looks like but its not in the exhaust

its in the cavity of the lower prop area of the stem (think thats what its called)

the engine seems to run like a charm, starts easy and idles great though may need some adjustment there

i just put it back together and i think i did a better job this time
though i suspect i will have to pull the gearbox out and im not confident as i have no idea what to do

also when i turn the throttle back to slow the engine stalls because the revs are to low, is this just an adjustment as when you put it in gear the throttle turns way past fast and the idle adjust screw on the side is screwed all the way in and is ineffective (doesnt do anything)

does gonzo mean stuffed ?

thanks for all advice

Ya, that exhaust tube goes down to the lower unit and exits the prop, the area you are talking about. That's unburnt oil/fuel, mine just look extra poopy cause I had a reed that was stuck open from a zip tie.

Don't pull the gearbox apart unless you have to, water in the lower unit turns the the oil milky, almost white, nothing like what is in the pic I posted unless it's been in there for 30 years.


When you idle it down to the point it's going to stall, try adjusting the idle mix screw, it may bring the rpm back up. The other point of wear is the roller on the carb and the cam on the magneto, make sure they are in good shape. I just changed my linkage and roller to the later style and bypassed the starter lock.

Gonzo as in gone so I had to replace it, or gonzo.

 

[Happyfingers]

Re: 15hp johnson 1975 impeller question

ahh ok that makes me feel a lot better

oh time to go to work now and stop playing with motors

so im gonzo

cheers

 

[Happyfingers]

Re: 15hp johnson 1975 impeller question

Also i noticed when i ran the engine for about 10 mins

it was quiet happily pumping water the whole time
it ran quiet well with nil issues

but when i turned it off and took the cover off
it had a little bit of smoke in there which i wasnt really concerned about (just curious is this normal)

also how hot should the head be ? it was too hot to touch (for any length of time) is that normal

thanks for all the advice

 

[Happyfingers]

Re: 15hp johnson 1975 impeller question

and because im using the fuel that came with the engine

i have no idea what fuel mix im supposed to be running

anyone know ?

 

[Xcusme]

Re: 15hp johnson 1975 impeller question

Sure, no problem ..... 50:1

 

[Happyfingers]

Re: 15hp johnson 1975 impeller question

ok some good news and some bad news

i put the tinny on the water and it floats
however the new water pump didnt seem to help its problem as its still overheating
the fuel leak i found and can fix easy
i pulled the mainifold off the head and found the thermostat and took it out
im mistified as to how this sytem works as i can find a hole for the water to come in but not one for it to go out, behind the thermostat there doesnt seem to be a hole for the water to exit or enter, ive tried poking around with a coat hanger but to no avail

i managed to break the head off a bolt and now have a stuck bolt in the hole
ive sprayed oil all over it and had one go with an easy out with no success as i cant seem to drill into the bolt, all my drill bits just spin with no actual drilling
they are cheap drill bits but i would of thought they would of been able to drill the bolt out (might have to go buy a better bit) so thats a bit of a mess at the moment

tried to get the head off as well but the heads of the bolts are stuffed and ill prolly need some sort of clamp onto any crappy bolt type tool

would like to get the head out of the mounts so its easier to work on but i need a special puller to get the flywheel off

im just about to give up and throw this engine in the bin
its a mystery to me as it starts easy and seemed to be ok until i actually took it out and it very quickly overheated, i ran it in the tub several times without any issues

i think it has a full water blockage somewhere i just need to find it

so im explaining all that to my aunty at a kids birthday party and she says to me, laury (her 8 year dead husband and my uncle) has a tinny and a engine up at the holiday home in venus bay that you can have for free if you want, she wants to get rid of it as she is selling the house.

so next weekend thats what we are doing
going to venus bay to get another tinny and engine
the engine will be in pristine condition as my uncle would of looked after it, being he was a aircraft engineer, so it will prolly just need a water pump

she doesnt know how big the engine is just that it is a evinrude

so as im bringing the tinny to shore with smoke coming from the fuel leak spurting on the hot engine, i plant it in the mud and tell the missus to get out first
i turn around to deal with the engine and i hear this splash i turn around and im completely unsuprised to find my wife laying in the water fully clothed, the iphone somehow survived and my car keys still worked so i could disarm the alarm

what a day that was

 

[Rick.]

Re: 15hp johnson 1975 impeller question

With the leg and head remove I would recommend that you connect a hose to the water tube and let some water run through giving the water way a good flush. If you had a manual (and I'm recommending you get one) there is an adequate drawing in it showing all the water passages from the intake to the exhaust. Your little story at the end makes me wonder if you have a plugged intake which will stop water flow regardless of the pump's condition. My best advice is to get an OMC factory service manual for your specific motor. You will get lots from it. In the mean time here is lots of great information you might find useful. Best of luck. Rick.

http://www.sschapterpsa.com/ramblings/OMC/OMC info.htm

 

[Happyfingers]

Re: 15hp johnson 1975 impeller question

why would the head be deliberately plugged ?

im confused
i tried putting a hose in the hole with the thermostat and nothing gets through

 

[Rick.]

Re: 15hp johnson 1975 impeller question

why would the head be deliberately plugged ?

im confused
i tried putting a hose in the hole with the thermostat and nothing gets through

I don't think anyone said it would be. I did say if your leg went into the mud there is a chance the water intake could be plugged. Rick.

 

[raczekp1]

Re: 15hp johnson 1975 impeller question

--------------------------------------------------------------------------------

Hi.
I had similiar problem with my Jo6HP/73y.the water flow was wery week.
i was looking for many casualitis,new impeler,new gromats, i took the powerhed of from mid section( i broke 3 of 6 bolts, but im maenage to unscrev one, and 2 of them to drile out) and clean water paseges under powerhead cover but the problem was in water pum.this thing was losing underpreseure, becouse there water pump housing athat cover impeler there was small space. so i put very thin bronze wascher(iner dinension equal witch the schaft, outer dinension 23 mm) and problem is gone.water is floating from my Jo as a river!
when I change the water pump imprler in my john6Hp/73y , but I wasnt sure if iput impeler in right way.Before I conect leg witch engines midsection I took bucket with water, put the leg on my engine in the bucket and conect the rod witch the driling machine(i use plastic tape to wrape around the end of the rod before i put it in the driling machine). run my driling maschine in right rotation and i could see if water is flating from water pump outlet

 

[Happyfingers]

Re: 15hp johnson 1975 impeller question

lol

thanks for the suggestions guys

i was ready to give up on this engine but dont like being beaten

i went out to the shed and had a further play, managed to find all the holes where water flows and the blockages that were in them
drilled out the broken screw and went from a 8mm thread to a 10mm thread on one of the bolt holes, it was touch and go with the available metal but it seems to have worked

removed the thermostat and threw it away (not even sure if it was working)

made a new gasket for the one that i wrecked when i took the water cooling manifold off

put it all back together, gasket goo on both sides of the gasket, fixed up the bolt hole where i drilled right through to the piston cyclinder sleve where the water circulates (liquid metal) white plummers tape on the thread just to be sure (as water was coming out this bolt hole, prior to me fixing it)

cleaned out all the drain holes that were blocked in the well of the engine

fixed the fuel leak that was causing problems and danger

let the goo dry overnight

started her up and ran it for a full ten minutes with water circulating, no leaks, no overheating, forward and reverse all working in good order

made sure i didnt overrev it as there was no load on the engine whilst in gear it would of quite happily reved itself to death

motor sounds stromg and is cooling itself
water comes out exhaust slightly luke warm and only occassional spurts and dripping out the hole thats just below the engine

you can hold you finger on the engine as long as you like, it doesnt get hot

taking it out to the river for a test run tomorrow
if all goes well ill register it and take the family out in it to do some snorkling

so all in all im feeling a lot better

fingers crossed

 

[bktheking]

Re: 15hp johnson 1975 impeller question

Overcooling itself, hope you replaced that stat, without one they run 50-70 degrees cooler than they should, it needs to run between 130 and 140 or so F.

 

[Happyfingers]

Re: 15hp johnson 1975 impeller question

dont say that LOL

whats the problem with it being to cool ?

i still have the thermo just dont want to pull it all apart again
dont even know if the thermo is working

arrhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh