Runnin hot...bah!

[TheTinMan]

At this point I was kinda hoping for a blown head gasket...easier fix than removing powerhead.

[kamikaze]

Tin:

What makes you think head gasket is bad if compression is good all around?

If water is getting into a cylinder then high water pressure could be understood due to compression stroke, but you said plugs are not steamed clean, nor is compression bad. so I don't understand why you think head gasket?

With all the bad head gaskets I seen, water always gets into the cylinder on the power-stroke at least when compression drops and vacuum is formed. Never seen a bad gasket that only flowed one way.

Bite the bullet, it's most likely going to be under the power head in the poppet's

Kamikaze

[TheTinMan]

I know it's NOT the head gaskets, think you misunderstood my post. I have a couple more things I want to try before removing the powerhead, but I do believe I will end up removing to find the blockage.

I can run all day @ 30-32 mph without a problem, it's when I go over 4000 rpm's, which I really don't do, when I get an alarm. But I need to find the problem cause it just ain't right :-/

[bigshrimpin]

Why would you pull the powerhead? I don't understand.

[TheTinMan]

Originally Posted by bigshrimpin

Why would you pull the powerhead? I don't understand.

If I can't find/clear the obstruction what other choice do I have ?

[kamikaze]

Tin:

Roger - I miss understood, although I have an idea that is off the wall but may just help verify what the problem is.

Temporarily remove the water hoses from the top of the heads and block as shown in the picture in your earlier posting and connect a new temporary drain hose with a manual on/off valve that is rigged to drain over the side. Run with the hood off and at speed open the valve. Verify water pressure drops and alarm no longer sounds. ( You should be by passing any blockage that may exist under the power head and the water flow should cool the motor as intended. At least then you'll know it's a blockage for sure vice a faulty alarm or something else inducing the problem.

Kamikaze

[spareparts]

Tin Man, your first post said the temp gauge was showing 145-150, make sure you're chasing an overheating problem and not a grounded out sensor wire. Disconnect the over heat temp switch wire( tan/blue stripe)at the sensor, run the boat and see what happens. The alarm wokrs off of a ground circut, anywhere in the harness, if the wire becomes grounded, it will set the alarm. If the poppet valve is removed, the block will not fill with water completely and create steem pockits. I wouldn't even bother with pulling the powerhead or lower unit till I confirmed the problem is high temp, and not a wireing problem.

[TheTinMan]

It's a PITA because I can't create the problem at home, needs to be running in the water at 4k rpm's plus. It's the PRESSURE and ALARM that makes me think there's an obstruction but I will verify it's not the sensor before I yank the powerhead.

[Kajun]

man..this is like deja vu!

[Seacrets]

Most marine dealers can flush your cooling system and remove any buildup of junk in the water passages. Are you getting water out the pee tube at 140-150. If it's like my Merc 150 you won't.