'89 Evinrude 90HP Piston #1 Keeps Blowing Out

janker

Cadet
Joined
Jul 9, 2005
Messages
12
Re: '89 Evinrude 90HP Piston #1 Keeps Blowing Out

Okay, I'm getting ready to put this thing back together once I pick the piston up tomorrow.<br /><br />If it is electrical, is the ignition coil the most likely source of the problem? I have ordered a new set of coils.<br /><br />My Clymer manual says to put gasket sealant between the block halves, which we have done the last 4 rebuilds. This, however, seems to be producing sludge in the crankcase, esp in the #4 cylinder. (A reminder that it is the #1 that keeps blowing out). The sealant that we used said it was fine to use where in contact with gas, but it appears that this is not the case. I have cleaned off what residue remained between the block halves. I have talked with several mechanics who looked at me like I had 2 heads when I said this is what the manual said to do. What is your opinion? Gasket sealant or no?<br /><br />Is there a way to test a carb jet to see if it is functional? Dhadley suggested that I bump up the mid and high speed jets. Is there a way I can verify that these things are even working before I go and richen up the mix?
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: '89 Evinrude 90HP Piston #1 Keeps Blowing Out

No gasket sealer!! <br /><br />Use Gel Seal. Its an anarobic sealer that hardens in the absense of air. <br /><br />Before you put it on make sure the surfaces are very, very clean and dry. Just before you put the Gel Seal on, put a straight edge on the block half. That flat edge gets pretty small right by the by-pass areas. Look real close at the #1 by-pass area. If that edge isnt straight -- stop!
 

janker

Cadet
Joined
Jul 9, 2005
Messages
12
Re: '89 Evinrude 90HP Piston #1 Keeps Blowing Out

what's your opinion regarding the electrical problem / ignition coils and checking the carb jets?
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: '89 Evinrude 90HP Piston #1 Keeps Blowing Out

The coils only send spark to the plugs when they're told to. I doubt they are the problem.<br /><br />If the carbs are clean, changing the jets will have the desired effect.<br /><br />BTW -- good job on taking the time to find and continue the original thread.
 
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