1971 Evinrude 18hp Cylinder Head

[JaSla74]

Greetings All,

I picked up this 1971 18102s about a year ago & it seems that if I'm not chasing part it's another on this one. I basically rebuilt the magneto along with some other maintenance, but I lost compression on the top cylinder here...



I've been snooping ebay for a replacement head, but if anyone can chime in what other years may fit or if they know of a parts motor please let me know.

I'm already in the market for another tiller, but I'd like to get this one back together for a secondary or just sell it. I'm debating on how deep to go, but the cylinder walls appear okay (outside of some carbon) & the rings don't look like they've let go. I dunno. Just ready to get out of the garage & on the water:\

 

[twocyclemania]

Re: 1971 Evinrude 18hp Cylinder Head

The pictures are pretty good and I'm looking at the tops of the cylinder walls. Both seem to have some degree of corrosion. They can be 'eaten' by electrolysis (salt and whatever) and you'll never get good compression - plus you'll get cooling water into the cylinder. In other words you'll never have compression. I picked up the identical (18) motor years ago, found the plugs wet, pulled the head and found just what I've detailed. The power head was toast. I thought about having the surface ground but I don't know if the tolerances would work. Maybe someone out there does know. If it can work you'd have higher compression and a faster 18. I still have the powerhead laying around for that day (that will never arrive) when I need parts. I bought a good powerhead, replaced it and had a great running motor.

 

[boobie]

Re: 1971 Evinrude 18hp Cylinder Head

Try the top secret files at the beginning of this forum and look for salvage yards.

 

[kfa4303]

Re: 1971 Evinrude 18hp Cylinder Head

HI ja. I just replaced the head gasket on my '66 20hp which is virtually identical to your motor. In fact these old FD/E models were practically unchanged from the mid 50s-mid 70s so there are tons of interchangeable parts around for cheap. I would check sites like ebay, aomci.org, marineengine.com, and right here at iboats for any parts you may need. Here are some great all around links to get you started. Holler if you get stuck. BTW, good to see another N. FL member in the forums too. I live right down the road (sorta) in Tallahassee.

1971 Evinrude 18102S 18 hp Outboard Motor Parts

Maintaining Johnson E & FD Serie

 

[JaSla74]

Re: 1971 Evinrude 18hp Cylinder Head

Thanks for the input fellas. I put a CL wanted ad & wouldn't you know a nice fella in Macclenny FL had just what I needed. Took a drive this evening to pick up & just ordered the a few gaskets. Hopefully I'll get her back together by the weekend.

 

[JaSla74]

Re: 1971 Evinrude 18hp Cylinder Head

So after a vacay & waiting on some miscellaneous parts to come in I finally had a chance to put her back together. Good news is she starts with one to two pulls. Bad news is she bogs down at WOT with the cowl on. Cowl off she planes quickly & runs fine.

My first thought is that she's choking on exhaust. However, I replaced the baffle gasket under the powerhead & it appears to be holding. Are there any other areas I should be looking for exhaust leaks. Also, what other causes are there for the motor to bog down with the cowl on? Thanks

 

[JaSla74]

Re: 1971 Evinrude 18hp Cylinder Head

Bumping for help. If no one chimes in I'll start a new thread.

 

[Chinewalker]

Re: 1971 Evinrude 18hp Cylinder Head

Check plug wires near the cylinder head and side. May be rubbing something and grounding out with cowling on.

Also, check exhaust cover gaskets for leakage. And, retorque bolts holding powerhead in place as your new gasket may be leaking.

 

[JaSla74]

Re: 1971 Evinrude 18hp Cylinder Head

Thankee. I'll take another crack at it tomorrow.

 

[Daviet]

Re: 1971 Evinrude 18hp Cylinder Head

You can use fogging oil injected into the carb to make smoke to find your exhaust leak.