1982 90hp Evinrude Compression

[Craftsman_85]

Ok Boat ran fine four weekends in a row. (first boat btw)was out the 5th weekend mid run at WOT the motor bogged down and slowly picked back up but not all the way felt like it was only runnin on 3 cylinders. Been troubleshooting the electrical while i was out of town had a friend playin with the motor Cylinder 3 wouldnt make any noticeable difference when it was unplugged changed the coil and it sounded alot better has good spark and motor has an equal drop in rpms now when each plug is disconnected one at a time. HOwever the plug on cylinder 3 when i just pulled it out has no fuel whatsoever on it. Did a compression test and low and behold 120 on all cylinders except 3. cylinder 3 has no compression at all. Cant order a factory manual until friday. Any help would be appreciated

 

[bktheking]

Re: 1982 90hp Evinrude Compression

Pull the head and check the gasket, head and/or cylinder walls for damage.

 

[Craftsman_85]

Re: 1982 90hp Evinrude Compression

I was planning on pulling the head whenever i come back in town after i get a factory service manual. It there anyway that a stuck reed valve could cause this? It is odd that the spark plug isnt getting any fuel on it at all.

 

[bktheking]

Re: 1982 90hp Evinrude Compression

A reed has nothing to do with compression, it's on the intake side of the motor. It wouldn't be getting fuel cause the lack of compression isn't causing fuel to be drawn in through the reed. A ZERO compression is indicative of a warped head or gasket issue I'm guessing.

 

[Craftsman_85]

Re: 1982 90hp Evinrude Compression

Ok, thank you for your reply. Ill wait for the manual and pull the head to see what damage has been done.

 

[bktheking]

Re: 1982 90hp Evinrude Compression

Pull the head, you don't need a manual for that! I have the same motor (1983), no biggie- if you need torque specs I can email them to you if the manual doesn't arrive on time. Check the head for warpage by holding it against a pane of glass.

 

[Craftsman_85]

Re: 1982 90hp Evinrude Compression

Well i have to leave tomorrow to go back out of town. If i get the weekend off ill do it then. Is there anything i should consider ordering to have in advance. Ive never really worked on a motor. Changed an alternator or radiator here and there but never anything like this.

 

[ezeke]

Re: 1982 90hp Evinrude Compression

Initially, just the cylinder head gasket so that you can replace the cylinder head if the gasket is bad.

You don't need to take the water cover off, just the cylinder head itself.

 

[Craftsman_85]

Re: 1982 90hp Evinrude Compression

Thank you for your quick responses. I will have memorial weekend off so I'll pull the head off when I get back on Friday night. Just curious as to why spark plug isn't getting any fuel at all yet there was a drop of rpm when that plug was pulled anyone ever have something like this happen?

 

[Craftsman_85]

Re: 1982 90hp Evinrude Compression

Ok so got the cylinder head off and The piston rings are shattered on it and the piston looks pretty nicked up on top. Im going too attempt to change this myself and as I've never done anything lke this any help would be very appreciated on how ths should be done correctly.

 

[ezeke]

Re: 1982 90hp Evinrude Compression

Basically, you have to pull the powerhead and disassemble it. At a minimum you will need to have a gasket kit, a piston and rings, new rod cap screws, plus whatever else you find.

You also need to discover and correct the reason for the failure so that it won?t happen again.

A factory manual on hand will make the job much easier.

 

[Craftsman_85]

Re: 1982 90hp Evinrude Compression

I am still waiting for the factory service manual. I decided to go ahead and break into her my question is do you have to pull the flywheel for this
process or can you pull the cover
behind the reeds without removing it