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Evinrude 1978 75hp repair needs help !!

J

JeanArr

Contributing Member
Hello everybody !!

Im trying to repair my 1978 Evinrude (Modelnr. 75842c) and need more than a little help:)

So the main problem is one of the pistons has a lower compression
(the one in the middle) than the two others and when turning the flywheel
you can feel that at the pistons "dead point" it is very hard to move the flywheel.

After some investigations i found out what the problem is.
One of the bearings between rod and crankshaft is broken.

Now my goal is it to remove the cylinder so i can get to the crankshaft what seems impossible to me!!:confused:

I already removed all screws that held the lower casing and all the screws that hold the cylinder together but i do not come any further because of Nr.20 in the following picture
Evinrude Crankshaft And Piston Parts for 1978 75hp 75842C Outboard Motor

I hope some one has experience with sth like that and can help me!! :(

Thank you already;)
 
There is one nut ( hidden ) at the back of the motor, it holds the block onto the exhaust housing did you remove that ?
 
I really believe i removed all screws but is it necessary to remove the ehaust housing?
If you want i go make some pictures right now.
 
There is one nut that needs to be removed !----Did you do that?-----------The motor block must be removed from the exhaust housing !--------Part # 20 is the seal retainer and the screws are on the bottom of the block !!
 
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Take a break !---------------------You must first remove the entire powerhead in order to take the motor apart.-----You are looking for a short cut and there is not one.--------------There are 4 screws that hold the seal retainer in place and you can not reach them the way you might hope.
 
Take a break !---------------------You might want to initiate a search for used replacement parts ,as this is not going to be cheap.
 
Yes thats the problem. I just didnt think that i would have to take the whole thing apart.
So Im going to remove the powerhead, the exhaust housing and then im going to post a new picture.
What would the next step be? Thank you:)
 
We have a online store in Germany where they have all necessery parts.
Where is the hidden screw?
I removed the exhausthousing next to the cylinderhead.
 
The cylinder head has to be removed in order to do this repair.---So remove the cylinderhead now and it will be easier to see the hidden nut at the back.
 
Okay I removed the six screws that hold the powerhead to the exhaust and now im going to remove the cylinderhead.
Thank you guys
 
You must find that nut ( hidden if you have never done this job ) --------before you can remove the powerhead.------Just follow advice here and you will make progress.----If not then you will damage expensive parts.
 
Allright!!:cool:
Found the secret Nut, Powerhead is off!!
Next step Flywheel off;) and then its almost done.
thank you for your help
 
Now the worst has happend:(
The broken bearing damaged of the middle rod damaged the crankshaft.
There is a little part of the chrome coating missing. I think that only a new bearing wont fix the problem and a new crankshaft is not worth it (1.100$).
Now it is possable to run the engine with 2 Cylinders but does that make sense or does maybe some one has used parts?
Thank you
 
Just like I suspected.------------------You need to find good used parts.----------------Measure cylinder bores. Measure pistons.Take lower unit apart and inspect it.-------Then decide what to do.------------------It might be best to find a used assembly on e-bay or a local dealer ( don't know how popular these engines were in Europe ) and if there are rebuilders over there.-----Lots available here.----------So do a search for rebuilt outboards / powerheads and see what shows up.-------------------Try ---crowly marine ------iboats ----as an example.-------------Running on 2 cylinders ???? I don't think so as there then may be a oil problem on one bearing and it would run a little rough.
 
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I already found the best solution.
I called a few engine service shops which fix car crankshafts and they said i could bring it to them tomorrow.
They grind, polish and coat the the thing and its good to go:)
 
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