Head gasket blowned between two cylinders ... Why ? See picture

[PeterboroughProject]

Hello to all of you !

I'm reading post here since couple of years and now I need some help

I have a Suzuki DT85 1987 Oil injection 3 cylinder.
Last year, I had a chek-up done on motor by Suzuki dealer, waterpump changed, carburator has been removed, cleaned and needles changed, then ajusted etc ... (cost over 600$)
Compression was 152 150 150.
I've run my boat about 25 hours since and one day, after fishing all day, on my way back an alarm came from dashboard. Overheat I guess.
The strange thing is that the motor was starting after that but I wasn't able to put it in forward without the motor to stop.
It was the last try I've done last years. The boat was winterized (Lots of snow here in Canada ...)
This spring, I started the motor in my driveway, everything was ok even on forward.
I took it to the lake. Everything was ok for 5 minutes, get to 30mph then loose power and motor shut off.
Now it does the same thing than last year, choking on forward but strange grey mixture come from the exaust.
I took the head off, here's what I found ...

Everything seem ok except that ... What should I do ... Changing the head gasket only will be ok ?

Thanks for future answer !

 

[stylesabu]

Re: Head gasket blowned between two cylinders ... Why ? See picture

head gaskets usually blow from overheat,depending on how hot it got will determine how fast gasket lets loose. check to make sure there is no warpage to head or block. then replace gasket replace t-stat and water pump and all should be well.

 

[PeterboroughProject]

Re: Head gasket blowned between two cylinders ... Why ? See picture

If the head is warped, can I see it by simply putting it flat on a table and look all around or it's not as easy ?

Btw thanks for helping !

 

[boobie]

Re: Head gasket blowned between two cylinders ... Why ? See picture

Get a good straight edge and check it with that. A carpenters square would even work.

 

[99yam40]

Re: Head gasket blowned between two cylinders ... Why ? See picture

I would take it to a machine shop and have it resurfaced or at least checked by them to make sure it is within tolerance.

I have used wet sand paper and a flat glass surface to resurface heads on smaller outboard heads, but this one could be too big to do like that.

And then you still need to check the block surface for straightness also

 

[PeterboroughProject]

Re: Head gasket blowned between two cylinders ... Why ? See picture

Really good advice 99yam40 ! Thanks !! I just tried to put water on a glass and put my motor head flat on it then flip it to look under, it appear to be perfectly flat

By the way, I don't have the repair manual ... Anyone know the torque for the head screw ? Is it the same for all screw ?

Thanks !