Evinrude 18 compression

autoed

Cadet
Joined
Feb 29, 2012
Messages
8
I have attempted to revive my dad's old 1965 18hp Evinurde. Mechanic (supposedly) replaced coil and points and rebuilt carb. Would't idle. Mechanic adjusted points. Idled fine. Second outing with the motor, it ran great for 15-20 minutes at full speed then started missing and shut down to about 25% power. I have decided to go at this myself because I don't really trust our local shop (I think he replaced original plugs with used ones). Pulled plugs and bottom one was oily black in appearance and damp. Replaced with J6C's. Tried again. Same thing. Hard to start, but ran great for a few minutes then went down on power. Compression test shows 90 in both cylinders. (Is that within spec?) Plug wires appear to be OEM. Could be an issue. Any other ideas? Someone had suggested fuel pump diaphram, but I couldn't find a fuel pump kit anywhere. Just replacement pumps. Is the pump rebuildable?

I am on my way to get a flywheel puller to check to see if the coil and points have actually been replaced.

Thanks for any input. I REALLY appreciate it.
 

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: Evinrude 18 compression

The compression is fine, have you checked the spark with an air gap spark checker, it should jump a 1/4" air gap and be bright blue.
Is your fuel pump mounted to the lower exhaust cover, could have a diaphram leaking causing a rich condition in that cylinder.
When it acts up you can use a self powered timing light to check the spark with the engine running to see if you are dropping a cylinder.
They do make a kit to rebuild fuel pumps (sierra), it is not listed for a lot of pumps but will work. You will have to go to their website and look it up. Have you checked the pump flow and pressure?
 

kfa4303

Banned
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Sep 17, 2010
Messages
6,094
Re: Evinrude 18 compression

Hi autoed. Welcome to iboats. Great old motor you have there. One o the all time greats, really. It sounds like you're dropping a cylinder, which isn't that uncommon and is pretty easy to fix. The good news is that the compression is seems to be ok. Anything over 80 psi with both cylinders being within 10% of each other is fine. Every thing else can be fixed with ease. You're probably dropping the cylinder becaue you have poor spark to one of the cylinders. While you could try to trouble shoot it all, it will be much easier to simply rebuild the ignition. It's a cheap, easy DIY job. You can get a tune up kit right here at iboats for about $20. Use the link below to walk you through the job. Be sure you pick up some (1/4" x 20 x 3") GRADE 8 bolts and washers for the flywheel puller as the ones that come with it are not strong enough for the job. Once the flywheel is off (be patient with it they can be stubborn sometimes) you'll be able to inspect the ignition. If the coils are scorched, or cracked they'll need to be replaced (again about $20 each here at iboats). However, if they look smooth and intact, they're probably ok. Next install a new set of points and condensers and gap them to .020" using a feeler gauge at the highest point on the crankshaft cam. I would also inspect/replace the spark plug wires themselves. You can try snipping about 1/2" of old wire off of the coil end in order to expose some fresh copper. However, if the wire still appears greensih/grey, you'll want to replace them. Be sure you use 7mm COPPER CORE wire. You can usually get it for a few $ a foot at many auto stores and/or small engine shops. That's really all there is to it. Once it's rebuild test each lead using an air gap tester ($5 at auto store). You should be able to get a bright blue spark capable of jumping a 1/4" gap with ease. With the spark and compression taken care of, all that's left is fuel. It's probably not a bad idea to clean/rebuild the carb if it hasn't been done in a while. Again, it's a cheap, easy DIY job. You can get a carb kit here for about $20. Use the link(s) below to walk you through the job. You can test the fuel pump before you replace it by, turning the motor off and squeezing the primer bulb. If it gets and stays firm then goes slack once the motor is running, then the fuel pump is probably ok. However, if the motor begins to die while running then picks up when you manually pump the primer bulb, then the fuel pump is probably bad. You'll have to check to see if your pump is rebuldable. I think it is, but I may be wrong. Give these links a read and holler if you get stuck.

http://www.leeroysramblings.com/johnson_E-FD_15_18hp.html

http://www.marineengine.com/parts/v...ntage-evinrude-johnson/380574/38057400001.htm

http://www.duckworksmagazine.com/06/columns/max/index6.htm

http://www.outboard-boat-motor-repa...on 3 HP 1952-1967 Ignition System Tune-up.htm

http://www.leeroysramblings.com/Rebuilding_fuelpump.htm

http://www.iboats.com/Johnson-Outbo...2237907--session_id.192146385--view_id.271265
 

autoed

Cadet
Joined
Feb 29, 2012
Messages
8
Re: Evinrude 18 compression

Kinda sounds like I was on the right track...but I sure do appreciate having a MAP now!!!!!!! Thanks, guys! The old Alumacraft FD will appreciate it one of these days. She's getting tired of the 3 mph that the Yachtwin 3 (my get back home insurance motor) is capable of.
 

autoed

Cadet
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Feb 29, 2012
Messages
8
Re: Evinrude 18 compression

Thanks for your info. You also helped me tremendously with an Alumacraft FD steering issue. Duckworks has all the right parts and I got a diagram (I think from you ) for cable routing. Thanks a ton. This boat (and motor) were purchased new by my Grandad, passed to my dad and then me. My dad is 83 and his health is failing quickly. I want to get him a ride in the old tub before he can't do it anymore. It is in almost perfect original condition and it means a lot to me. Your help has saved me a lot of time.
 

kfa4303

Banned
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Sep 17, 2010
Messages
6,094
Re: Evinrude 18 compression

No prolemo. Keep us posted on your progress. We love pics ;)
 

autoed

Cadet
Joined
Feb 29, 2012
Messages
8
Re: Evinrude 18 compression

Working on the pics. Can't remember where I put the ones I took. It is funny how that boat and it's freshly painted red trailer, which was purchased with the boat in 1956 get so much attention at the lake. It never fails that someone stops to comment or ask questions. Lots of love out there for the ol' girls I guess. Will keep you posted, next time with some freshly snapped photos. As a suggestion to anyone out there reading the forum, I found a terrific way to freshen the aluminum on an old boat like this. I went to my local truck stop with a truck wash (wash lots of aluminum trailers and wheels, right?) For $20, believe it or not, they applied a citrus-based cleaner to the boat and washed it completely. It came out looking bright and beautiful without being polished. Took the grime from 30 years of sitting under oak trees right off and made her look like a new nickel.
 

kfa4303

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Sep 17, 2010
Messages
6,094
Re: Evinrude 18 compression

Cool. Did you happen to catch the name of the stuff? I've heard of Alumabrite, but it's some kind of an acid-based aluminum cleaner. It works well, but I'd rather not mess with any crazy chemicals, if at all possible.
 

autoed

Cadet
Joined
Feb 29, 2012
Messages
8
Re: Evinrude 18 compression

I will have to check. I don't think it was Alumabrite. The name started with Citra...something or another. Worked amazingly well. I was shocked. Didn't etch the aluminum o alter it in any way. No streaks either. Here is a pic of my baby. 1965 18hp and 3-horse "get-home insurance" motor mounted and ready to go. I have the original steering wheel and original console, but they are not installed. Easier fishing without them.photo.JPG
 
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