New to me 1974 evinrude 70....need overhaul advice.currently siezed.

[240240]

As title states. Manual trim. Was ran in salt water for about 3-6 months, sat in a mooring. Previously a freshwater boat.

Engine siezed...pulled head and found rust in hole #3.....also cyl#1 has excessive play side to side at near tdc.engine still siezed with my impact wrench at the flywheel bolt....

. Reading up on here, next step is to pull the lower unit and start looking there.....

How do I pull the lower unit from the power head? Am I wasting my time with an old nla engine?


The ignition coils are new....other than that, the previous owner showed me a video of when the ran it.....said he docked it. Came back a month later and siezed.....I purchased a new starter for it and still siezed...hence the teardown....so I might as well tear it all down and go from there.....locally on cl there's late 80s Johnson 70s that are for sale for $1000 that "run"......

Also the prop looks to be in poor shape...cracks in center and cracks at blades.....need advice there as well.


..https://m.flickr.com/#/photos/99626820@N03/sets/72157661395980063/

 

[F_R]

You already have established that the problem is in the powerhead, not the lower unit. Well, you could have lower unit problems also, but that is a different story. You need to to pull the powerhead and tear it down & inspect. Once the powerhead is off, you can make sure the LU isn't also seized simply by turning the shaft.

From prior experience, I can tell you that the powerhead most likely is junk. Water (salt, even) squirts from a warped exhaust cover plate, into the exhaust ports and destroys the entire powerhead.

 

[240240]

You already have established that the problem is in the powerhead, not the lower unit. Well, you could have lower unit problems also, but that is a different story. You need to to pull the powerhead and tear it down & inspect. Once the powerhead is off, you can make sure the LU isn't also seized simply by turning the shaft.

From prior experience, I can tell you that the powerhead most likely is junk. Water (salt, even) squirts from a warped exhaust cover plate, into the exhaust ports and destroys the entire powerhead.

Got it. I probably will have time to pull the powerhead between today and tomorrow.

I'm currently leaving trans fluid to try and release the piston. But there is no budge. This sieze looks hard, and looks like its coming from behind as you mentioned...I didn't see any damage to the head gasket, the head looked like it was sealing properly.

 

[racerone]

The various popular lotions and potions will not work.------Time to take it apart to see if anything can be salvaged.

 

[240240]

This thing is definitely done.... There's another 70 Johnson locally that I may pick up so I can have a spare parts engine....I can't find decent outboards in this size for less than $1000, even for old roached out ones....the one in I referred in supposedly has a new impeller and carbs rebuilt...

 

[flyingscott]

To use the one you have as a parts motor will have to 76/77 and earlier to have the lower unit work.

 

[phillnjack2]

dont get to down. now to completely rebuild that into a as new engine is going to cost less than a good secondhand one.
you main worry is that the crank and rods are good, piston and rings are dead cheap, and maybe a rebore is called for..
in total that powerhead can easy be rebuilt for $500 and be as good as new, that's including carb kits to rebuild those too..
but you need to get right into this motor before buying anything, as you could get right in and find its too far gone, or might be lucky and
find everything in the block is good.
I think tear all the way into it then check out the prices of a rebuild kit.