Failed 25 hp head gaskets

[Brokeback Johnson]

This summer we have repaired three early 80's OMC 25 hp engines that suffered a head gasket failure. All engines had little or no compression.......after installing a new head gasket each had 130-140 psi in each cylinder and ran perfectly.

Has any one else experienced this with these engines? What's going on here?

http://i124.photobucket.com/albums/p12/swedesleds/25hpheadgaskets.jpg

 

[flintcreek]

Re: Failed 25 hp head gaskets

I have 2 35 hp that are 77 and 82 models that had the same problem....heads and blocks did not seem warped and compression was 130 + on both motors after putting on new head gaskets....both went bad between the cylinders, just like your pictures. Fixed the 82 last year and it ran good, but looks like it is going to need a clutch dog. Fixed the 77 a month or so ago and now compression is good, but it is still not wanting to run. I have a DVA attachment for multimeter ordered, hopefully I can figure it out next week and get it fixed.

Flintcreek

 

[JB]

Re: Failed 25 hp head gaskets

Do you have a handle on what torquing sequence was used on those heads?

On those twins I always start at the center and work out, then retorque after a few hours of operation.

 

[Brokeback Johnson]

Re: Failed 25 hp head gaskets

Yes we use never-seize on the head bolt threads and torque gradually from the center out.