Blown Head Gasket? Update . . .

[NoName]

My original post was due to over heating. I pulled the boat out and yanked the drive off. (A great learning experience. I recommend it to everyone.) But no flapper down there. So I pulled one of the risers off (Merc 888) and pushed a rubber hose down the exhaust pipe. I could hear the flapper open and close. It looks like all is well there. With everything back together, I started it up with the muffs on. I get warm water out of the drive, but it still overheats. It looks like a leak down test is next. But could it be a head gasket when it runs so well, and I have no water in the oil?

 

[Don S]

Re: Blown Head Gasket? Update . . .

Short of me having to search page by page of your previous posts, and since the search feature is basically usless. What have you already checked?
No need to start with the basics if they have been checked.

 

[NoName]

Re: Blown Head Gasket? Update . . .

Here's the short & skinny. I purchased the boat late last fall. I was told that the impeller was bad, so I took it directly to a mechanic who replaced it. While there, it got new plugs, points, & timing checked. At present, the new impeller doesn't' have 20 hours on it, and I never ran it without muffs. This spring it started getting hot at idle, but cooled back down when over 1500 RPM. Over 2 weeks it got progressively worse, until now, it won't run for 15 minutes without overheating at-- any speed. I've pulled the risers and opened the mans & hoses. All are clear. It overheats with or without a thermostat in it. The outlet hose from the lower unit gushes water and the risers are cool to the touch, so I assume the impeller is still good. I removed & inspected the circulating pump and it looks good. It moves water when spun by hand. Never been in salt water. The only thing left is a head gasket, but as I mentioned above, the thing runs great, starts quickly, and has a smooth idle. It's got me baffled.

 

[NoName]

Re: Blown Head Gasket? Update . . .

I just went out and started it up with the muffs on. Within just a few minutes, the temp guage went to the red. I shut it off. The mans felt hot, but the risers were cool. I pulled the thermostat and it was still closed. The water below it was warm, but not hot enough to burn the fingers. Do I have a bad sending unit or a bad circulating pump?

 

[lilmandavis]

Re: Blown Head Gasket? Update . . .

sending units are cheap enough to replace just to make sure. the circ pump unless totaly rotted out rarley stops pumping. might make noise and leak but wont stop moving water. id start with temp sender and thermostat. after it goes into the red zone is it hard to start? like rarrrrummph rarrrrummph? or does it turn over like normal?

 

[NoName]

Re: Blown Head Gasket? Update . . .

I never let it get fully into the red zone. When it gets to the dividing line, I turn it off. But it will start back up with a quick turn of the key . . . no grinding the stater at all.

 

[Haut Medoc]

Re: Blown Head Gasket? Update . . .

I would still pull apart the drive & visually inspect the impeller myself....
You are getting your water pressure from your hose, not your impeller....
You need to check your impeller yourself....
Did I say that your impeller is probably bad?
Check it yourself...
I'm willing to bet $ at this point.....JK