Blown head gasket?

[Headbanger]

I have a 2001 Yamaha HPDI 150. Tons of smoke started pouring out the upper exhaust port. So much smoke I thought I had a fire, so I shut it down and got towed in. There is no obvious signs of a problem, all the oil lines look ok, no leaks inside the cowling. Some oil came out through the prop exhaust when I rinsed at the washdown. Does this sound like a blown head gasket or oil injector problem?

 

[rodbolt]

Re: Blown head gasket?

sounds like the oil level switch in the engine tank failed and the oil transfer pump would not shut off and started filling the airbox with oil causing the lower cyl's to swim in oil. or the oil link rod broke at the pump. both are quite common.

 

[Headbanger]

Re: Blown head gasket?

I checked my oil sensor this morning and found the vent hole on the strainer was not aligned with the flat part of the sensor. The manual says it MUST be aligned properly. I can't really tell if the nipple is correctly seated in the bottom of the tank, but I assume it is or I couldn't put the assembly all the way in. Could this little vent hole cause that much grief? I haven't started it up yet to see if it's cleared up. BTW the link rod looks ok.

 

[Headbanger]

Re: Blown head gasket?

I reinstalled the oil sensor and started it up. It smoked for about 10 seconds then most of it went away. It still smokes more than normal though. I checked the plugs and they are all fouled with some gunk about the same amount on each one. I will start checking other oil system components switch, float, pump etc tomorrow.

 

[rodbolt]

Re: Blown head gasket?

if you pulled the strainer out of the engine oil tank its imperative to find the old seal and discard it and replace it with a new seal. if it was not on the nipple of the strainer its bobbing about the tank or worse got forced into the oil feed pipe.<br /> the usual failure indicate of a mispositioned strainer is delayed oil transfer shut off. the second is its popping the sender assy out of the tank.

 

[Headbanger]

Re: Blown head gasket?

I saw it floating on top of the oil. I think it just slipped off as I was pulling the strainer out. I reused the old one but I noticed it wasn't a snug fit on the nipple. I will get a new one for sure. If this is the problem and the delay pumped too much oil into the crankshaft, how long would it take to burn off and not see any smoke? Do I need to do anything else to clean the excess oil out of the engine?

 

[Headbanger]

Re: Blown head gasket?

I took my boat in to the shop and the mechanic said he couldn't find anything wrong with the oil system but found water in the fuel. He's draining the fuel tank and putting a fuel/water seperator. Does this sound like it will correct my problem? It might at least partially explain the smoke but it doesn't explain the oil coming out the prop exhaust during the flush out.<br /><br />I remember getting a piece of kelp stuck in my prop just before the smoking incident. Could that have caused a temp overflow of oil?

 

[Headbanger]

Re: Blown head gasket?

Well it turned out not to be an oil problem after all. The mechanic said I had water in the gas tank. He did run diagnostics it came up clean. compression test showed one cylinder to be a bit low at 105, rest are 118, one was 110. He changed the plugs, fuel filter and installed fuel/water seperator. I guess the engine mounted seperator is not good enough. I took it home and started it, it seems fine, no smoke. We'll see how it performs on the water.