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1974 evinrude 50hp

19K views 22 replies 7 participants last post by  Bubbakat 
#1 ·
i have a 1974 evinrude 50 hp that i recently acquired. got her on the boat and started her up in the driveway in a tank of water with a hose running in it.
she idled excellent for the 5 minutes she was running before i decided to shut her down. the reason for this is... there was no water coming from the tell tale.. on my 33 hp it would shoot water from the telltale the second you fired it up and until you shut it down. i was reading on a site that this motor has "auto pressure temp control, warning buzzer" so does it wait until it gets to a certain temp before it starts pushing water?? or???
i already have plans to get a new impellar/water pump ASAP as i know it wont hurt having a new one. i dont want to run it if its not going to cool properly.

btw.. the model number is 50473M.. thanks again for any input..

it has a different cowl on it.. i have the original but the seal on it is bad.

 
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#5 ·
I'm saying that I don't see a port in the lower cowling for the discharge, and it may not have one. It might be just like the older ones with a discharge after the thermostat opens.

I always put in a new water pump with any engine I get. A new thermostat should also be installed when you do a water pump. They work together for proper engine operating temp.
 
#6 ·






heres a couple photos i took this evening.. maybe give you a better idea..

you would think water would come out of the 2 holes on the rear of the motor... after starting it in the driveway.. air blows from these holes (exhaust?) for a couple minutes.. then stops. ?

sean
 
#7 ·
i got a few more pictures for ya's of the actual motor idleing. i let it run until the head of the motor was getting close to too warm to touch. then shut it off. the first picture is of the motor running of course.. and the second picture is the motor right after turning the water off, engine off too.





i called a local marine place today and said they could get me a water pump kit for 73.99 and a thermostat and gasket for it for like $24. thats a lot more than a water pump kit for my 33 ($22). anyways.. im probably going to switch both out and was wondering if this model of motor will be similar to taking apart like my 33. it has electric shift whereas the 33 had manual shift.. what other problems will i come across doing this myself??? thanks again.

sean
 
#9 ·
Yup, you need a water pump, thermostat would be real nice too.

They won't be difficult to change. I think the shift shaft disconnects underneath the carbs. Wait!!! It's electric shift. no shaft, but I'm sure there's a wire that needs disconnected

There will be a wire to the lower unit that needs disconnected. I have no idea where. Never worked on one, nor even seen a diagram.

You'll need the proper lower unit oil, and I'm told it's been out of production for a long time. Got no idea what you can use. I know some older shops have some hidden away. You've got to hunt it up.

Bubba , can you help him on the wire disconnect or the oil?
 
#11 ·
Wires to the lower unit are blue and green. Interesting wires. LOL. They are located on the starboard (right) side of the engine, and have a disconnect on them.

A man that works on these old motors told us (my friend FuzzFace and I) that you are to use a type c lower unit oil. However, he said if you could find it, it was quite expensive ($5.00 qt, minimum) and we should use dextron transmission fluid instead.
 
#14 ·
made a call today to a local boat parts store for parts for my motor....i got into explaining to him what my problem was and he told me that this particular style of motor, while in idle will not "spray" water. he then said if you let it idle for 10 minutes and it was still cool enough to touch (which it was) then it is probably cooling properly.. ?

im getting 2 different answers to my problem... i know im still going to replace the pump and thermostat in time.. (fixing my other motor now and money is kind of an issue, at $100 for part especially) i was hoping to get the boat out over this upcoming 4th of july weekend.

im in a predicament.. what should i do?????
 
#15 ·
Gotta scratch my head on this one also. Took pictures with the motor running. Have no idea why I'm not getting any water from the exhaust, unless the pumps out. Have to wait until I get the shop manual in to find out, I guess. The first picture shows water exiting from the two holes on the starboard (right) side of the engine before it is started. The second photo shows an area that water comes out of when the motor is running. The upper stream of water is gone when the motor runs. I'm stumped...guess I should have been born rich so I could just buy a new engine.
 

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#16 ·
thanks for the reply... when my motor idles.. it has water coming out of a few areas on the lower part of the unit (see pictures earlier in post) but only a very seldom, faint spit out of the two holes seen in picture below while idling.. im assuming this is the "telltale" as its the only place i can see water would come from if the motor would be submerged in water. ? im stumped.. i keep getting different answers to the problem.. grrrr...


sean
 
#20 ·
My understanding is that the regular fluid is so thick it will not lubricate the parts in the lower unit, causing failure and expensive repairs. Maybe the ports (holes) are small, don't know. I know you use 90W oil in a car/trucks rear axle, and only a few of those will take 90W in the transmission. Gotta go with what the engineers have said, and they said a type C fluid, not the regular flood.

I thought those two slots were the exhaust for the water pump, and that the pee holes were the little small streams that comes out the sides of the motor. Never saw a water pump exhaust out of the side.
 
#21 ·
Sean, I just found out today that our motors exhaust through the hub of the propellor. Was told to put it in a barrel of water (not to use a hose) or in a lake. Run the motor and keep your hand on the block. If it gets hot enough to burn you, your water pump/impellor is bad. If it just gets warm, every thing is okay.
 
#22 ·
Alright lawerence is getting on the right track here. Those two oblong holes are exhaust relief holes. Water will pass thru them sume at idle but on muffs it will only mist thru them. The pump really needs changing and I can beat that price but you will have to order from the internet and this guy really takes care of you.

The Type C oil used in that lower unit is a good refined transmisson oil.
Those engines didn't come with the tell tell hose but if interested I can send you a drawing of where to drill and size to put a pee hole in it.:big_smile:

Set it in a barrell of water and fire it up and let it run. The T-stat should open at about 140 degrees. Feel of the mist comming out of the relief holes and if it is real warm then ck the head to see how hot it is.

On droping the lower unit go to where awshucks said on the right side and look right down inside the cowling and there are the two wires. They are or should be knife blade connected and slip right apart but be sure to tie a string to them so you can feed them back up thru the houseing to reconnect them. If you don't do this get ready for some big cuss words because they are a bugger to feed back up thru there. If I have left anything out let me know.

Oh yea the regular oil in the lower unit won't work because it is to thick and won't let it shift. You have to use a type c oil.Light weight good stuff:lol:
Make sure you replace those little round gaskets under the fill and drain screws.
I am going to search for the right part number and link so you can order the kit.
 
#23 ·
Alright Sean here goes.

I see you live in IOWA. Now do you have a NAPA auto parts store or an O"riely parts store there?
If you do then both have a catalog that can order these parts for about 2 day delivery. or I can hook you up on the net.

Impeller part number 18-3083

Wear plate. Thise one is a must) 18-3343

Water pump kit with out the cup housing which i can't find) 18-3376

Now you can order these parts from this site I order from and the first one

18-3083 impeller 13.77 your cost

18- 3343 wear plate 8.21 your cost

18--3376 water pump kit without housing your cost 29.47

The shipping will be between 10 or 11 dollars.

If you just get an impeller then get the top two that will be plate and impeller.

or get the kit that has plate rubber gromments and impeller new bolts well worth the money.

Over the years I have found that the plat wears and causes most problems with the impeller sucking air up thru them and thus no water to cool with.

I like replaceing the whole pump assembly when possible.

This is a long way from 100.00 in my book.

But a 100 bucks is still cheaper then a power head.
 
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