1981 Evinrude 25HP Blown Engine

[jdixon22]

I nabbed a 25hp Evinrude outboard at a garage sale for $40. Guy said one of the pistons was bad. It has a new starter, new carberator, overall looked clean (freshwater only). Anyhow, nothing was seized so I took the chance and gave him $40 for it.

Get it home pull off the piston head find the top cylinder piston is burned with metal shavings inside, cylinder wall scourned minorly.

I know I can get new oversized pistons and have the cylinders bored out etc. My question is, the cylinder head over the top piston is also burned with pieces of the blown rings etc. burned into the casting of the cylinder head. Do I need to replace the cylinder head? Can I clean it up and re-use? It isn't cracked. There are a few pieces of piston ring fused in and the "high" areas of the surface are pitted/rough. I found that I can get a new cylinder head at cost of $370, just not sure if it's worth it....

 

[wilde1j]

Re: 1981 Evinrude 25HP Blown Engine

Replace the head:

Salvage yards:
sea-way.com
outboard-parts.com
laingsoutboards.com
tcoutboard.com
fairwindsmarina.com
salvagemarine.com
marinepartsoutlet.com
Superior Marine (800-338-9281)
trixieslanding.com Trixie?s Landing, Bayville, NJ 732-269-5838
americanoutboard.com
piratemarinesalvage.com/

 

[Al-53]

Re: 1981 Evinrude 25HP Blown Engine

There was a few heads on ebay....check there......I am not sure..but I think the 20 to 35 will fit....like I said not sure....my OMC manual sorta shows them all alike..may be different on the inside for a compression ratio.....

but check ebay

Al

 

[jdixon22]

Re: 1981 Evinrude 25HP Blown Engine

Thanks wilde1j...

Called marinepartsoutlet.com and they had 1 for $150, matched by the cast number.

Once I get the cylinder head and make sure all is well, I will look into the cylinder problem.

Is it easy to simply get and replace the cylinder sleeves or just bore them out and go a size up in pistons / rings? I would imagine that the piston size would be dependant on how much wider the cylinders have to be bored out..

Sorry for the noob questions, never messed around with cylinders and pistons...

 

[wilde1j]

Re: 1981 Evinrude 25HP Blown Engine

Bad hole needs to be bored. Let the shop tell you the oversize. Don't use an automtive shop. The following is a list of good shops:

Mar Fab -- talk to Kurt or Dan at 931-738-2815 (Tennessee)

Flagship

Tribble

Blackburn

Roehrs

Riverside

Get an OEM shop manual if you plan to do the labor. BTW, you need to determine the cause of the failure, or it surely will happen again.