Mercruiser 470 head and gasket inspection

[Max-Falcon]

Hi everyone
I am in a Merc 470 water in oil situation. I get water or coolant (not sure yet) when running engine on muffs. Since I knew at least one case of engine overheat event had taken place, I decided to service the head anyway. Can someone have a look at the attached 2 photos of the head and the block and tell me if they see any clues for leaky HG or anything else. At this point I'd very happy if my HG is bad and issue is not cracked head or block!
P.S. I forgot to drain the AF when I loosened the head bolts so all the AF in cylinder 4 was not there when the head bolts were tight. Also I did not clean anything when I took these 2 shots just to preserve clues!

 

[Bt Doctur]

between the top 2 cylinders looks blown

 

[Scott Danforth]

You didnt do a pressure test?

 

[nola mike]

between the top 2 cylinders looks blown

Agreed, that shot of the head. Less likely that you'd have a cracked head/block, though certainty possible

 

[Max-Falcon]

You didnt do a pressure test?

I did a rad pressure test before taking down the riser and manifold. Pumped 15psi, it dropped to 14psi almost immediately, then stayed there for about an hour that I had the tester on.
Then I did another cooling system pressure test with riser and manifold off ( blocked hoses) this time It was loosing pressure very slowly but steadily. Is that what u meant by pressure test?

 

[Max-Falcon]

Agreed, that shot of the head. Less likely that you'd have a cracked head/block, though certainty possible

I’m sending the head to the machine shop to do what machine shops do with heads, machining, pressure testing, check for warps etc. is that the correct way To deal with this issue?

 

[rallyart]

I’m sending the head to the machine shop to do what machine shops do with heads, machining, pressure testing, check for warps etc. is that the correct way To deal with this issue?

With the head off, that is a good idea. You'll need to clean off the surface of the block too. A ScotchBrite pad on a drill is a good way to to that by yourself after you use a scraper to get rid of chunks. They'll likely want to do the valves too. That will add to the cost but might be worth it while you are working on the head. Once you take things apart there is always more you could do so it's a question of deciding on the value your add.
My old boat had the 470 in it and it lasted week over 3000 hours, including being underwater once. It smoked a bit more after that but we never had to take it apart.

 

[Scott Danforth]

I did a rad pressure test before taking down the riser and manifold. Pumped 15psi, it dropped to 14psi almost immediately, then stayed there for about an hour that I had the tester on.
Then I did another cooling system pressure test with riser and manifold off ( blocked hoses) this time It was loosing pressure very slowly but steadily. Is that what u meant by pressure test?

if you pressure tested the block, the block should have been empty. you do the cooling side pressure test empty.

 

[kenny nunez]

You better remove the timing cover and install a Speedy sleeve over the water pump impeller shaft along with the 2 seals. The “weep” hole in the bottom of the cover is plugged up. Most times when coolant enters the oil that is the reason especially if there is no blown out sections of the head gasket, Having the head machined is a very good thing that you are having done.

 

[Max-Falcon]

You better remove the timing cover and install a Speedy sleeve over the water pump impeller shaft along with the 2 seals. The “weep” hole in the bottom of the cover is plugged up. Most times when coolant enters the oil that is the reason especially if there is no blown out sections of the head gasket, Having the head machined is a very good thing that you are having done.

The weep hole wasn't leaking. I pushed a paper clip in the weep hole to make sure it is not plugged, it went in for about a couple of inches or so, still no leakage when engine was running. Based on this can I conclude that water in oil is not from failed camshaft seals?

 

[kenny nunez]

Looks like you lucked out, most times however those seals are the cause. Since there are no cam bearings in the block over tI’ve the cam “sinks” which is another cause of the seals leaking.
Just keep a watch for coolant in the bilge.

 

[Max-Falcon]

Head is back from the machine shop. They said it had no crack or other damage but had a little warp which was fixed with resurfacing. I got all the gaskets too. Is there anything I should do (test, repair, etc.) before the assembly? Also any particular tricks of trade for this head assembly beside instructions mentioned in the service manual?