Head gasket?--(w/pics) UPDATE

[Dave Abrahamson]

1997 Johnson 115SPL
J115HXEUA

Overheated a few times while scalloping due to major floating grass everywhere.
The motor now gets to maybe 3000 RPM and falls on her face trying to plane out.
Went to check coils with a spark tester and found this when I pulled the bottom port cylinder spark plug.
Spark looked fine on all 4. I'm hoping it's just a head gasket.
I'm getting a compression tester next.
Should I do both gaskets? Or is that overkill?
The other plugs looked fine.

Thanks..(and thanks for the other times you've helped me out)
Dave

 

[Joe Reeves]

Re: Head gasket?

Re: Head gasket?

Check the compression on all cylinders.

I see no evidence of pre-ignition on that plug.... just water wetness. In all probability a head gasket leakage (lets hope).

 

[1946Zephyr]

Re: Head gasket?

Re: Head gasket?

May as well do both, since the head gasket set will probably come in a pair. Besides that, if the one side went, it's likely the other won't be far behind. One other thing you might check to, is the inner plate on the exhaust cover. The aluminum ones like to get pinholes eaten through and they sometimes have a good enough angle to squirt water into the exhaust port.

Do like Joe Reeves suggested first and check the compression. That cylinder should read lower than the other three, if it's blown. If your compression is good, then I would pull the exhaust cover.

 

[Dave Abrahamson]

Re: Head gasket?

Re: Head gasket?

Thanks guys...will do
I will post back with results

 

[Dave Abrahamson]

Re: Head gasket?

Re: Head gasket?

When I'm changing the head gasket(s), do I need to use new head bolts?
Do they stretch when you torque them down?
Thanks
Dave

 

[boobie]

Re: Head gasket?

Re: Head gasket?

No. Just clean up the threads on the bolts and in the block.

 

[Dave Abrahamson]

Re: Head gasket?

Re: Head gasket?

OK Update,
I did a compression test and the results were not as I expected.
The top port cylinder was 110/115 psi
The bottom port cylinder,(where the milky watery plug came from), was also around 110/115 psi.
The top starboard cylinder....around 80 psi
The bottom starboard cylinder was 110/115 psi

What do you think?
Exhaust cover needs to come off like 1946Zephyr said? Its a bubbleback if that makes a difference
I guess I'll find out when I pull the heads.

Thank again

Dave