1973 65hp Evinrude leaking+bad cylinder compression

Hello iboats I am new here and could use some help. I recently bought a boat and after a couple of rides a couple of days ago i went on the lake and about 15 min. after i went out the motor started making an awkward noise (knocking sound) I turned of the engine. tried to turn it back on and it wouldn't. (seized). after getting towed back home I removed the spark plugs then tried to turn over and it did. Did a compression test and I get 120, 120, 30... obviously this is horrible.. but also oil is leaking from somewhere under the engine because after turning it over oil comes out of the casing so its visible from the outside. Also if i try turning it over around 5-6 times it may seize up, until i pull the spark plugs back out. Sorry if my details dont explain much, but I am new to boats, but good with car mechanics. 2 strokes are different to me but I'm understanding them more.


I am wondering if this a job that I could maybe handle, and also what could have caused this? I took each spark plug out and each one is letting off spark.

Re: 1973 65hp Evinrude leaking+bad cylinder compression

The bad news is that what you describe sounds like your motor overheated due to a lean carb causing detonation or lack of water flow to the powerhead. I am suspicious by the knocking sound that you have a bad wrist pin in a piston. I'd even suspect that a connecting rod has broken and cracked the case except you still have 30psi of compression. Due to the age of the motor, I'd look for a good used powerhead on the auction sites. Boring the cylinders, new pistons/pins, rings, rods, and powerhead gasket set is probably the very least the motor needs and since the motor is so old, it's not worth the price to rebuild in my opinion-- a good used powerhead is much cheaper if you can find one. I could be totally wrong---I'm not a professional marine technician, so hopefully a true expert will answer your post.
Good luck and I hope I'm wrong,
JBJ

Re: 1973 65hp Evinrude leaking+bad cylinder compression

Thanks for the fast reply. Yah it does sound like a lot of work, you probably are right. Guess I should just take the head of and see whats going on. Just seems weird that it seemed to drive perfect for about 2-3 hours the days before when I was driving it, and then this happens.

Re: 1973 65hp Evinrude leaking+bad cylinder compression

Those motors gave a lot of trouble from water ingestion into the cylinders, coming from warped and leaking exhaust covers. That destroys the bearings and everything else inside the powerhead. Hey, the suddenness of the failure is the point at which that first part to break happened. You are not the first to experience it.

Re: 1973 65hp Evinrude leaking+bad cylinder compression

Thank you. I may try to open up the engine myself to investigate.. I would do it without a heart beat because I can redo car engines with easily, but this is a little different. Im also more familiar with fuel injection instead of carbs. Does anyone know if a regular automotive machine shop would be able to do the same kind of work on a 2 cylinder block? I may take it to the same place that does my car engines. Guess ill just give them a call. Ill keep you guys updated with pics hopefully soon when I open it up and you can give me your final opinion. I also found another engine like mine on craigs for 500.. Im wondering if I should swing towards that direction.

Re: 1973 65hp Evinrude leaking+bad cylinder compression

The looper block has huge ports in the cylinder walls, that scare some machine shops off. I notice you are in Florida. Unfortunately, we are here where the lakes have lush vegetation fouling. That causes overheating when you get stuck in the "hayfields". Just the slightest hint of overheating will warp the exhaust cover baffle plate, long before you even realize it is getting hot. The result is what I described above. Saying all this to say be careful when buying one. I don't know of any way to tell if there is a problem before the damage rears its ugly head.

Re: 1973 65hp Evinrude leaking+bad cylinder compression

I see. Im going to try and open it up on my next day off..

Re: 1973 65hp Evinrude leaking+bad cylinder compression

I have pictures!.
(it was sprinkling when I took pictures)
So i opened it and there are scratches and a big piece of metal stuck on the piston. How can you tell if the walls are scraped to bad? only a machine shop can tell? I also found what seems to be a piece of hose around the cylinder walls where the water flows.. any idea where that could have came from?

Let me know how i can make the pictures smaller.
Plan on taking of power head today hopefully!