no cooling in the top, heat indicator burned

[marinus]

So, I have been having some issues with my 1980 Johnson 50hp Seahorse (aka the seawhore). Broke down on me two weeks ago and I fixed the carbs and checked the ignition before I realized I only had 25psi in each cylinder. Took the top of today and found the head gasked had failed around one cylinder (the steel ring was broke). So I started to look around for the cause of the overheat and found the heat indicator that is connected to alarm all black and not working. The thermostat works properly and opens up.
When I do fix this, how can I be sure that the water is getting all the way up to top? I looks like no water has been up around the cylinders, that area is more covered in some oil and carbon stuff. Can the escaped pressure and heat make the water not getting up?
I saw before that the indicator beam was kind of weak, especially on idle. What else can cause this, I had the impeller replaced before it happened so that should work. When I had it on land running with the muff, I noticed that most of the water is getting out via the exhaust, can the water take a "short cut" and not circle all the way?

 

[jonesg]

Re: no cooling in the top, heat indicator burned

take a photo, especially of the water deflectors in the head.
You might need to have the head trued up or do it yourself, they can warp slightly when overheated (blown gasket).

 

[marinus]

Re: no cooling in the top, heat indicator burned

I think I can get the head back in good shape, doesn't look to bad. I did run it very hard when it happened and I can still turn the disk by hand pretty easy. But I'm worried that the top isn't getting water?

 

[HybridMX6]

Re: no cooling in the top, heat indicator burned

If the head gasket blew by a water jacket, the water would have been going into that cylinder, so it is possible water was not getting circulated properly. Would also explain the rather clean one vs. a rather dirty cylinder.
Also, you can pull the lower unit off and make sure they got the water pump aligned properly with the water tube in the midsection, as well as while it's off, pull the t-stat and stick a water hose into the hole and back flush the system and see if anything comes out. A trashcan with some screen over it works well to collect the water pouring out of the midsection when you do this, and should collect and noticable pieces that could cause a water flow problem. For instance, if your old water pump impeller had fallen apart, or a piece fell off, part of it could have got lodged up in the tube leading to the powerhead.