Estate sale lot of 18 - 25hp motors - Compression gauge variables.

slowleak

Petty Officer 1st Class
Joined
Feb 21, 2011
Messages
209
Day two, lots of heat, large pry bars, pb blaster, and the head won't budge?
Am I missing something here? I've applied enough force under the tabs of the head to break it in two but it won't budge.
If its glued on somehow, its likely not coming off anytime soon by the looks of things After sitting soaking in hot penetrating oil overnight, and being heated with a torch for an hour I've gained no ground on getting the head to break free of the block or gasket.

I'm getting close to just running a hole saw through the face of the head to just salvage the rods and pistons and throwing the whole powe head in the scrap pile. If I use any more force than I've been using, there likely won't be anything left anyhow. If a 10 ton hydraulic spreader won't separate the head from the block, there's likely not much that will.


Not really related to my original post here but I've got a half dozen Stihl chainsaws and every one of them uses a felt air filter, so does my old Homelight. The Stihl saws use a felt covered screen, the Homelite has a stiff felt filter in the shape of the side cover opening. The Stihl saws are fairly new, all from the 90's or 00's, the Homelite is mid 60's.
I don't think I've ever seen a saw with a foam filter.
This fits my 036 Pro, and my 024, 026, 029, 034, & 056 use the same or similar filters. My Stihl concrete saw uses a round paper element.
Stihl 036.jpg
 

cyclops222

Lieutenant Commander
Joined
Mar 21, 2024
Messages
1,800
Sounds like someone GLUED the head on with epoxy.
Parts motor now.
Might have done other areas also.
 

Mc Tool

Petty Officer 2nd Class
Joined
Aug 7, 2024
Messages
186

Day two, lots of heat, large pry bars, pb blaster, and the head won't budge?
Am I missing something here? I've applied enough force under the tabs of the head to break it in two but it won't budge.
If its glued on somehow, its likely not coming off anytime soon by the looks of things After sitting soaking in hot penetrating oil overnight, and being heated with a torch for an hour I've gained no ground on getting the head to break free of the block or gasket.

I'm getting close to just running a hole saw through the face of the head to just salvage the rods and pistons and throwing the whole powe head in the scrap pile. If I use any more force than I've been using, there likely won't be anything left anyhow. If a 10 ton hydraulic spreader won't separate the head from the block, there's likely not much that will.


Not really related to my original post here but I've got a half dozen Stihl chainsaws and every one of them uses a felt air filter, so does my old Homelight. The Stihl saws use a felt covered screen, the Homelite has a stiff felt filter in the shape of the side cover opening. The Stihl saws are fairly new, all from the 90's or 00's, the Homelite is mid 60's.
I don't think I've ever seen a saw with a foam filter.
This fits my 036 Pro, and my 024, 026, 029, 034, & 056 use the same or similar filters. My Stihl concrete saw uses a round paper element.
View attachment 405507
Are you able to remove the intake side of the crank case ? Dunno about your motor but some the crank assy inc pistons etc is fitted up thru the base of the cylinders unnamed (1).jpgunnamed (2).jpgunnamed (3).jpg

This is my Tohatsu M18d , as you can see in the last pic there is nothing to stop you pounding the 5hit out of the underside of the head :D.
I dismantled it for these pic's for you ;).............actually thats bulls hit , in my eagerness to assemble my pile of new bits ( crankcase and crank assy are Chinese parts ) I forgot to check the ring end gap . I agonised over it for a month or so reasoning that I couldnt remember the last time I actually had to take a bit off a ring end so she'll be right , but I couldnt stop thinking about the ensuing disaster if this was the one I should have checked , so I pulls it to bits and .... yeah , book says min 7 thou and I had 10 in one pot and 13 in the other so all good , now I just gotta get some more gaskets .
 

Mc Tool

Petty Officer 2nd Class
Joined
Aug 7, 2024
Messages
186
???---Cylinder head MUST be removed in order to get the pistons out of these fine Johnson / Evinrude motors !
Yeah , the last Jonnie I had used a con rod with a removable cap anyhow with the removable cap the rod and piston can be disconnected from the crank and pushed out the top but with proper 2 stroke motors 😆 the rods are one piece and the crank components are pressed together and the whole plot is shoved in from the bottom of the case .
6 of one and 1/2 dozen of the other .
 

slowleak

Petty Officer 1st Class
Joined
Feb 21, 2011
Messages
209
The head has to come off, the piston skirts won't even go down that far,
If I could drop it all out the bottom, I'd have smashed the head off the thing from below. The bad part is the thing ran, I just wanted to see why its got such high compression.

If they had epoxied the head on all the heat would have killed that bond already. I also don't see any sign of any glue around the seem, it all looks very factory that way. The only bolts that gave me trouble were the four inner exhaust cover bolts, all of which broke off but left enough to get hold of later.

At this point I've taken everything off it besides the head and pistons The crank and all other parts are off and tagged for future use elsewhere, I'll likely just take it to the drill press and cut the head off with a hole saw to get the rods and pistons out. At this point, the head us getting sacrificed to maybe save the block but its more a battle of wills than anything else.
 

Mc Tool

Petty Officer 2nd Class
Joined
Aug 7, 2024
Messages
186
Ah OK , hard to know what to do next ........ go hard Dude , dont spare the horses :LOL: maybe as a last effort get real serious with the heat , wait until the Mrs is out and chuck it in the over ( she has been with me for 37 years :D for those of who just wondered :LOL:) or get the torch out , but yeah a hole saw would get you the pistons and rods , shame aye but the rest of the parts have a habit of coming in handy :)
 

cyclops222

Lieutenant Commander
Joined
Mar 21, 2024
Messages
1,800
Why I never buy anything used. Some dirtbag screws anyone buying his junk. (n)(n)(n)(n)(n)(n)(n)
 

aspeck

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May 29, 2003
Messages
19,029
Dunno cyclops , I wouldnt have ANY vehicles at all , or a boat ..... or a house .
just gotta know your stuff :) and walk away if it seems suss (often triggers a reduction in asking price )
Yep, in another life I sold new cars ... would never want to buy one though ... let someone else take the depreciation hit and get a good used one at half the price, then run it till the wheels fall off is my motto! Works for me!
 

Crosbyman

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Joined
Nov 5, 2006
Messages
5,573
wd40 is good stuff
 

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starcraftkid

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Jul 5, 2010
Messages
238
I had a 1968 18hp short shaft tiller motor that belonged to a neighbor who passed away some years ago and left me his boat and motor. He had the 18hp hanging in the garage because he couldn't pull start it any more in his 70's. He had bought a new motor with electric start, and power tilt. I kept his boat for a while but found one cleaner and swapped the motor over. I hung the original motor and thought maybe it had gotten carboned up so I pulled the head and found someone had already doubled the head gaskets.
With two gaskets it gave me 195 psi with three pulls. I mounted a starter on it and it tore up the used starter in five starts. I bought it a Chinese starter and a larger battery with larger cables and sold the thing with the boat and never saw it again.
Once it was running it felt like a 30hp not 18.It ran circles around the new four stroke that I kept.
 
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