Powerhead Plumbing

[peety]

First post on this terrific forum.
I have a 87 Johnson 150 vro(removed and pre-mix fuel) that has just been thru a head gasket(both sides) and water pump project. The shop removed both center plates between the heads(v plates?) . The port side head gasket was leaking exhaust into one of the water journals and over-temping the engine. Now the engine is cooling properly with both side thermostats opening properly.
My question: There is now lots of grey & black oily water acumulating above the foot/gear housing section. I know water is supposed to be coming out of the mating points but have never seen the oily water issue. It has cooled to the 50's in my area and now the exhaust has lots of blue smoke during the first 5 minutes of warm up with a cuff for cooling...Do I have a problem...Thanks for any suggestions.

Also, what is the water plumbing setup behind the two plates between the heads? The mechanic said the pistons looked good? Could there be a water leak in this section?

 

[emdsapmgr]

Re: Powerhead Plumbing

Water can get into the lower cyls of any crossflow if the head gaskets are leaking. Your description of the plates is probably the exhaust manifolds/covers. It also is very possible that leaky exhaust manifold gaskets can leak water into the exhaust chest. Sounds like your mechanic took care of both possibilities-a very correct fix on his part. You can see the good results in the current cooling. When that engine runs, the unburned fuel does mix with the spent cooling water, causing the dark substance you mention. Usually this mixture exits out the prop only. If it is exiting above the lower unit, you may have another minor issued. If the lower unit was recently remove(for water pump replacement) is is possible that the large oring around the exhaust tube may not have been aligned correctly during reinstallation. This can permit the spend exhaust to exit the lower unit in other areas. While not a huge problem, you may want to get it corrected sooner rather than later. If the exhaust gases are misdirected, they leak into the water cavity around the plastic water pump housing. That housing does not like to be overheated and can suffer from shortenened life over time.

 

[peety]

Re: Powerhead Plumbing

Thanks. I see a small amount of water weeping out of a small pin hold (just a small drop every two to three minutes) on the bottom of the exhaust manifold cover. I don't remember seeing this before. He removed both exhaust manifold covers during the repair due to hot spots. It is now very even and cool once the thermostats open. I will try to post a pic of where the water is exiting from the middle section and foot.

Two Questions. It appears he replaced the exhaust manifold bolts(some snapped off) with stainless bolts. Also one head bolt appears to be stainless. Will this not create a problem down the road due to electrolysis. Lastly, Can this water seeping into the exhaust chest create a problem.

Thank You Very Much

 

[emdsapmgr]

Re: Powerhead Plumbing

After replacing a head gasket or exhaust gaskets and the engine is run a couple of times, the head bolts and the exhaust manifold bolts should be retorqued. You may find that this will take care of the minor leak at the bottom of the exhaust manifold. It is also possible that the manifolds were installed without any sealant. You can apply some permtex type sealant to those gasket surfaces, which may also stop the leak. Water in the exhaust chest can be a problem if/when it gets ingested into the combustion chambers of the lower cyls. That will promote rust, misfiring, and may even cause a hydraulic lock-if too much water gets in the cyl. All of these are bad situations. If you observe that the top of the piston appears to have a "washed" (clean) appearance, you may have an internal water problem. The piston tops should normally be dark brown, or black.

 

[peety]

Re: Powerhead Plumbing

Behind the outside exhaust plate should be exhaust only? No water? Mine is a flat plate, not a bubble back. There are two plates according to the schematics. Thanks Again for this valuable information.

 

[emdsapmgr]

Re: Powerhead Plumbing

Yes, you have two exhaust covers. The inner and the outer. Water is in the cooling cavity between the two plates-only. Both covers use the same gasket...