1995 onwards 50/60/70hp triple cylinder heads porous ?

**phillnjack** · 03-10-2019, 04:03 PM

I have the 1995 3 cylinder 60hp evinrude and infact 2 of them, 1 good and 1 for spares as its a sister motor but a bit too far gone to repair..
so the cylinder head from the spares engine needed work and I took to sanding it down, ideally about 80 thou so as to get a higher compression,
a bit nearer to the performance cylinder head of a sst60 but in keeping with being able to use pump gas.. so far so good.
Now for the dodgy bit.

Once I started with 40 grit wet n dry on the dead flat surface ( yes thats right 40 grit) due to this head needing to go down by such a
round 70 thou to get it back to level surface all over and ideally down around 80 thou to get the compression I want, I noticed that
tiny little pin holes are in the head surface !!! not just in a few spots here and there, but all over the head.
At first I put this down to maybe damage while its been knocking around in the workshop and not sitting on a dead clean surface.
So then I start getting the head down by around 20 thou and instead of seeing less of these micro pin hole things I start seeing even more.
Obviously not realy happy with seeing these pesky little thing so look around to see if anyone else has these on their cylinder heads.
Not only was I shocked to see a few with similar little holes, but I also then see a few brand new old stock heads for this motor and that
too has the identical little holes just not so many of them on the surface. ( mine was not showing much at surface to begin with)
This head is now down by 60 thou and it seems like there is no end to these pin holes, when one lot gets sanded out another bunch appears.
I am now down to 120 grit paper and will soon be going to around 250 then maybe even 400 for a final finish when I get real close .

Now before I go much further, what is the deal with these pin holes, will the head still be ok ? would the gasket seal up ok with these all over
the head ? I am mainly worried about the fire ring on the head more than anything else.

is this an issue with other motors from OMC in that era ? or just on the later 3 cylinder motors in the 1990's.
pic below shows pin holes
zoomed in pic of mine and pics 2 and 3 are a brand new cylinder head showing the same little pin hole marks

.

**FMP** · 03-10-2019, 04:20 PM

Old trick which may help, hit the surface with rattle can paint just before assembly.
Depends how perforated it is .

Permatex 80697
And related products by Permatex
https://www.permatex.com/products/ga...-temp-sealant/

**phillnjack** · 03-10-2019, 07:16 PM

yeah I was thinking a etching primer or something similar to keep the water from pitting the head , the perforations are just what you see, they dont
go deep or anything, it is just tiny micro air bubbles and I just cant get over these motors having heads like this.
apparently its due to gases when molding them. some say cooled to fast and some say its hydrogen in the smoke from the lost foam ? I have no idea, but
think its a terrible thing for omc to have let these out the door.. I had not even noticed this until the first few passes with a bit of paper, and thought it
must of been my dirty work bench or similar, but the more I sand it then the more little pin hols come back.
each hole is about 8 thou diameter and about 3 thou deep.

**FMP** · 03-10-2019, 07:50 PM

Unless a trail of holes are leading from the chamber the gasket will likely conform, plus a bit of insurance with the sealant. Try it .

**phillnjack** · 03-11-2019, 06:41 AM

This all the head gaskets ive seen for the omc 56 say NO sealant !!!!
I was thinking a drop of sealant , but got told dont use any. I cant sea a reason not too ?

**Motv18** · 03-11-2019, 05:02 PM

Heat and it has to be anarobic or arobic? I forget which. But mainly the heat on the head is to high and breaks down the sealants.

**LittleCharger** · 03-12-2019, 05:45 AM

Very common on the omc heads, if your concerned before you do your final true up on the head you can fill the holes with JB weld (apply with a razor blade) then sand out.

**racer** · 03-12-2019, 07:34 AM

Normal for lost foam castings.

**phillnjack** · 03-12-2019, 01:49 PM

Ok Racer I appreciate your answer that lost foam castings are all like this, from what ive seen this is the case..
But will this be ok with the normal gasket ? or do I need to add something to it or just put a gasket on and forget about it.

Also , going from 140 to 145 psi with it in normal size then cutting down 60 thou any idea of how much the compression might bump up ?

thanks in advance

**phillnjack** · 03-12-2019, 02:09 PM

Motv18
Heat ? outboards dont get as hot as car and truck motors and they often have head gasket sealants...
average car temp is 200f, average outboard temp 145f... I would prefer NOT to have to use any sealer.

**racer** · 03-12-2019, 02:14 PM

About 160 and nothing on the gasket.

**FMP** · 03-12-2019, 02:52 PM

Might make a decent motor out of it yet!

**Instigator** · 03-12-2019, 07:28 PM

As Racer said, it'll be fine w/just the gasket.

Ive experimented w/sealer even though the factory manual says not to.
Had a 3.3 that leaked water to cylinders no matter what and tried sealer.
It worked for a while but not long.

Get the head straight/flat, install a new gskt and torque to spec.

**Motv18** · 03-13-2019, 06:28 AM

Yep heats the main thing, the other is cure method.

Yea if that’s the appropriate application then go for it.

Rules of thumb are just that smash them with a hammer.

edit: sory bout that. Bad day